Critical evaluation of the 2D-CSIA scheme for distinguishing fuel oxygenate degradation reaction mechanisms

Although the uniform initial hydroxylation of methyl tert-butyl ether (MTBE) and other oxygenates during aerobic biodegradation has already been proven by molecular tools, variations in carbon and hydrogen enrichment factors (ε(C) and ε(H)) have still been associated with different reaction mechanisms (McKelvie et al. Environ. Sci. Technol. 2009, 43, 2793-2799). Here, we present new laboratory-derived ε(C) and ε(H) data on the initial degradation mechanisms of MTBE, ethyl tert-butyl ether (ETBE), and tert-amyl methyl ether (TAME) by chemical oxidation (permanganate, Fenton reagents), acid hydrolysis, and aerobic bacteria cultures (species of Aquincola, Methylibium, Gordonia, Mycobacterium, Pseudomonas, and Rhodococcus). Plotting of Δδ(2)H/ Δδ(13)C data from chemical oxidation and hydrolysis of ethers resulted in slopes (Λ values) of 22 ± 4 and between 6 and 12, respectively. With A. tertiaricarbonis L108, R. zopfii IFP 2005, and Gordonia sp. IFP 2009, ε(C) was low (<|-1|‰) and ε(H) was insignificant. Fractionation obtained with P. putida GPo1 was similar to acid hydrolysis and M. austroafricanum JOB5 and R. ruber DSM 7511 displayed Λ values previously only ascribed to anaerobic attack. The fractionation patterns rather correlate with the employment of different P450, AlkB, and other monooxygenases, likely catalyzing ether hydroxylation via different transition states. Our data questions the value of 2D-CSIA for a simple distinguishing of oxygenate biotransformation mechanisms, therefore caution and complementary tools are needed for proper interpretation of groundwater plumes at field sites.

Urinary methyl tert-butyl ether and benzene as biomarkers of exposure to urban traffic

Methyl tert-butyl ether (MTBE) and benzene are added to gasoline to improve the combustion process and are found in the urban environment as a consequence of vehicular traffic. Herein we evaluate urinary MTBE (MTBE-U) and benzene (BEN-U) as biomarkers of exposure to urban traffic. Milan urban policemen (130 total) were investigated in May, July, October, and December for a total of 171 work shifts. Personal exposure to airborne benzene and carbon monoxide (CO), and atmospheric data, were measured during the work shift, while personal characteristics were collected by a questionnaire. A time/activity diary was completed by each subject during the work shift. Spot urine samples were obtained for the determination of MTBE-U and BEN-U. Median personal exposure to CO and airborne benzene were 3.3 mg/m(3) and 9.6 μg/m(3), respectively; median urinary levels in end-of-shift (ES) samples were 147 ng/L (MTBE-U) and 207 ng/L (BEN-U). The time spent on traffic duty at crossing was about 40% of work time. Multiple linear regression models, taking into account within-subject correlations, were applied to investigate the role of urban pollution, atmospheric conditions, job variables and personal characteristics on the level of biomarkers. MTBE-U was influenced by the month of sampling and positively correlated to the time spent in traffic guarding, CO exposure and atmospheric pressure, while negatively correlated to wind speed (R(2) for total model 0.63, P<0.001). BEN-U was influenced by the month and smoking habit, and positively correlated to urinary creatinine; moreover, an interaction between CO and smoking was found (R(2)=0.62, P<0.001). These results suggest that MTBE-U is a reliable marker for assessing urban traffic exposure, while BEN-U is determined mainly by personal characteristics.

Kinetic properties of three isoforms of trypsin isolated from the pyloric caeca of chum salmon (Oncorhynchus keta)

Three isoforms of anionic chum salmon trypsin (ST-1, ST-2, and ST-3) were purified from the pyloric caeca of chum salmon (Oncorhynchus keta). The molecular weights of the three isoforms were about 24 kDa as determined by SDS-PAGE. The isoelectric points of ST-1, ST-2, and ST-3 were 5.8, 5.4, and 5.6, respectively. The apparent K(m) values of two isoforms (ST-1 and ST-2) for BAPA (benzoyl-L-arginine-p-nitroanilide) hydrolysis at 5, 15, 25 and 35 degrees C were slightly higher than that of the main isoform ST-3, depending on temperature. The turnover numbers, k(cat), of ST-1 and ST-2 were about twice as high as that of ST-3. Consequently, the catalytic efficiencies (k(cat)/K(m)) of ST-1 and ST-2 were more efficient than ST-3. There were marked differences in both apparent K(m) and k(cat) values of three anionic chum salmon trypsins as compared to bovine cationic trypsin. K(m) values of all chum salmon trypsins were approximately 10 times lower than those of bovine trypsin, depending on the temperature. The k(cat) values of all chum salmon trypsins were about 2- to 5-fold higher than those of bovine trypsin; therefore, the catalytic efficiencies (k(cat)/K(m)) of chum salmon trypsin were 20- to 40-fold more efficient than those of bovine trypsin. On the other hand, k(cat)/K(m) values of ST-1 for TAME (tosyl-L-arginine methyl ester) hydrolysis were lower than those of bovine trypsin, whereas k(cat)/K(m) values of ST-2 and ST-3 were comparable to those of bovine trypsin, depending on the temperature.

Purification, primary structures and evolution of coagulant proteases from Deinagkistrodon actus venom

Deinagkistrodon (formerly Agkistrodon) actus (Taiwan) snake venom was found to contain at least seven closely related coagulant proteases. One of them, named actibin, was purified to homogeneity by means of four chromatographic steps. Actibin acted on fibrinogen to form fibrin clots with extremely high specific activity of 1,630 NIH units/mg and preferentially released fibrinopeptide A. Actibin was an acidic glycoprotein (pI 3.4) with molecular weight of 41,000, which was reduced to 28,800 after deglycosylation with N-glycanase. The k(cat)/K(m) values of actibin for hydrolysis of tosyl-l-arginine methyl ester and benzoyl-l-arginine p-nitroanilide were one-third to a half those for thrombin, reflecting a high potency of actibin in fibrinogen clotting. The amidase activities of actibin and its family proteases were inhibited by 3,4-dichloroisocoumarin, a serine protease inhibitor, indicating that actibin and its family proteases are serine proteases. Four cDNAs, named DaP1 and DaP7-DaP9, encoding D. actus coagulant proteases were cloned. All cDNAs contain an open reading frame of 780 bp coding for 260 amino acid residues, including a signal peptide of 24 amino acid residues. Their amino acid sequences predicted are highly homologous to one another with one to five amino acid substitutions. When four D. actus protease cDNAs were compared with the cDNAs coding for Trimeresurus flavoviridis and T. gramineus venom serine proteases, accelerated evolution was clearly observed. Similarity of the nucleotide sequences of four D. actus protease cDNAs with no synonymous and one to five nonsynonymous substitutions seems not to be in direct conformity with accelerated evolution. This possibly suggests that they have evolved to a similar direction to enhance their clotting activity rather than to produce other physiological activities.

Isolation and characterization of trypsin from pyloric caeca of Monterey sardine Sardinops sagax caerulea

Trypsin from pyloric caeca of Monterey sardine was purified by fractionation with ammonium sulfate, gel filtration, affinity and ionic exchange chromatography. Fraction 102, obtained from ionic exchange chromatography, generated one band in sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and isoelectric focusing. The molecular mass of the isolated trypsin was 25 kDa and showed esterase-specific activity on Nalpha-p-tosyl-L-arginine methyl ester (TAME) that was 4.5 times greater than amidase-specific activity on N-benzoyl-L-arginine-p-nitroanilide. The purified enzyme was partially inhibited by the serine-protease phenyl-methyl-sulfonyl fluoride (PMSF) inhibitor and fully inhibited by the soybean trypsin inhibitor (SBTI) and benzamidine, but was not inhibited by the metallo-protease inactivator EDTA or the chymotrypsin inhibitor tosyl-L-phenylalanine chloromethyl-ketone. The optimum pH for activity was 8.0 and maximum stability was observed between pH 7 and 8. A marked loss in stability was observed below pH 4 and above pH 11. Activity was optimum at 50 degrees C and lost activity at higher temperatures. The kinetic trypsin constants K(m) and k(cat) were 0.051 mM and 2.12 s(-1), respectively, while the catalytic efficiency (k(cat)/K(m)) was 41 s(-1) mM(-1). General characteristics of the Monterey sardine trypsin resemble those of trypsins from other fish, especially trypsins from the anchovy Engraulis japonica and Engraulis encrasicholus and the sardine Sardinops melanostica.

Influence of oxygenated fuel additives and their metabolites on gamma-aminobutyric acidA (GABAA) receptor function in rat brain synaptoneurosomes

Experimental and occupational inhalational exposure to oxygenate fuel additives in reformulated gasoline has been reported to induce neurological symptoms (e.g., headache, nausea, dizziness). We reported previously that the ether additives (methyl-t-butyl ether (MTBE), t-amyl-methyl ether (TAME) and ethyl-t-butyl ether (ETBE)) and their metabolites (t-amyl alcohol (TAA), t-butyl alcohol (TBA) and ethanol) alter the binding of [3H]t-butylbicycloorthobenzoate ([3H]TBOB), a ligand for the gamma-aminobutyric acidA (GABAA) receptor in rat brain membrane preparations. To more directly assess the effects of the ethers and their alcohol precursors on GABAA receptor function, the uptake of 36Cl- was measured in synaptoneurosomes, a preparation of closed membrane sacs comprised of pre- and postsynaptic membranes from adult rat cerebral cortex. Each of the compounds caused a concentration-dependent enhancement of muscimol-stimulated uptake of 36CI-, which diminished with further increasing concentrations. The potency of the enhancement by the compounds was in the rank order: MTBE = TAME > TAA = ETBE > TBA > ethanol. The half-maximally effective concentration (EC50) for the facilitation of muscimol-stimulated 36Cl- uptake ranged from 0.06 to 3 mM, and that for the higher-dose inhibitory effect (IC50) ranged from 3 to 50 mM. The facilitatory concentrations of the compounds are in the range of the blood concentrations reported in experimental animals after exposures known to induce CNS effects such as ataxia. The results suggest a potential role of the GABAA receptor in some of the reported neurotoxic effects of gasoline additives.

Biotransformation of MTBE, ETBE, and TAME after inhalation or ingestion in rats and humans

The biotransformation of methyl tert-butyl ether (MTBE), ethyl tert-butyl ether (ETBE), and tert-amyl methyl ether (TAME) was studied in humans and in rats after inhalation of 4 and 40 ppm of MTBE, ETBE, and TAME, respectively, for 4 hours, and the biotransformation of MTBE and TAME was studied after ingestion exposure in humans to 5 and 15 mg in water. tert-Butyl alcohol (TBA), a TBA conjugate, 2-methyl-1,2-propanediol, and 2-hydroxyisobutyrate were found to be metabolites of MTBE and ETBE. tert-Amyl alcohol (TAA), free and glucuronidated 2-methyl-2,3-butanediol (a glucuronide of TAA), 2-hydroxy-2-methyl butyrate, and 3-hydroxy-3-methyl butyrate were found to be metabolites of TAME. After inhalation, MTBE, ETBE, and TAME were rapidly taken up by both rats and humans; after termination of exposure, clearance from blood of the ethers by exhalation and biotransformation to urinary metabolites occurred with half-times of less than 7 hours in rats and humans. Biotransformation of MTBE and ETBE was similar in humans and rats after inhalation exposure. 2-Hydroxyisobutyrate was recovered as a major product in urine. All metabolites of MTBE and ETBE excreted with urine were eliminated with half-times of less than 20 hours. Biotransformation of TAME was qualitatively similar in rats and humans, but the metabolic pathways were different. In humans, 2-methyl-2,3-butanediol, 2-hydroxy-2-methyl butyrate, and 3-hydroxy-3methyl butyrate were recovered as major urinary products. In rats, however, 2-methyl-2,3-butanediol and its glucuronide were major TAME metabolites recovered in urine. After ingestion of MTBE and TAME, both compounds were rapidly absorbed from the gastrointestinal tract. Hepatic first-pass metabolism of these ethers was not observed, and a significant part of the administered dose was transferred into blood and cleared by exhalation. Metabolic pathways for MTBE and TAME and kinetics of excretion were identical after ingestion and inhalation exposures. Results of studies presented here suggest (1) that excretion of MTBE, ETBE, and TAME in rats and humans is rapid, (2) that biotransformation and excretion of MTBE and ETBE are identical in rats, and (3) that biotransformation and excretion of TAME is quantitatively different in rats and humans.

Isolation and characterization of two aerobic bacterial strains that completely degrade ethyl tert-butyl ether (ETBE)

Two bacterial strains, E1 and E2, isolated from gasoline-polluted soil completely degraded ethyl tert-butyl ether (ETBE), as the sole source of carbon and energy, at specific rates of about 80 mg g(-1) and 58 mg g(-1) of cell protein day(-1), respectively. On the basis of morphological and phenotypic characteristics, strain E1 was tentatively identified as Comamonas testosteroni and strain E2 as belonging to Centre for Disease Control group A-5. The inhibitory effect of metyrapone on the degradative ability of both strains was the first evidence indicating the involvement of a soluble cytochrome P-450 in the cleavage of the ETBE ether bond. This observation was confirmed by spectrophotometric analysis of reduced cell extracts that gave, in the presence of carbon monoxide, a major absorbance peak at about 450 nm. Both strains were also able to degrade, as the sole source of carbon and energy, ETBE's major metabolic intermediates (tert-butyl alcohol and tert-butyl formate) and other gasoline oxygenates (methyl tert-butyl ether and tert-amyl methyl ether). The degradation rates varied considerably, with both strains exhibiting a preferential activity for ETBE's metabolic intermediates.

Anaerobic biodegradability of alkylphenols and fuel oxygenates in the presence of alternative electron acceptors

Alkylphenols and fuel oxygenates are important environmental pollutants produced by the petrochemical industry. A batch biodegradability test was conducted with selected ortho-substituted alkylphenols (2-cresol, 2,6-dimethylphenol and 2-ethylphenol), fuel oxygenates (methyl tert-butyl ether, ethyl tert-butyl ether and tert-amylmethyl ether) and tert-butyl alcohol (TBA) as model compounds. The ortho-substituted alkylphenols were not biodegraded after 100 days of incubation under methanogenic, sulfate-, or nitrate-reducing conditions. However, biodegradation of 2-cresol and 2-ethylphenol (150 mg l(-1)) was observed in the presence of Mn (IV) as electron acceptor. The biodegradation of these two compounds took place in less than 15 days and more than 90% removal was observed for both compounds. Mineralization was indicated since no UV-absorbing metabolites accumulated after 23 days of incubation. These alkylphenols were also slowly chemically oxidized by Mn (IV). No biodegradation of fuel oxygenates or TBA (1 g l(-1)) was observed after 80 or more days of incubation under methanogenic, Fe (III)-, or Mn (IV)-reducing conditions, suggesting that these compounds are recalcitrant under anaerobic conditions. The fuel oxygenates caused no toxicity towards acetoclastic methanogens activity in anaerobic granular sludge.

Purification and characterization of a thrombin-like enzyme, elegaxobin, from the venom of Trimeresurus elegans (Sakishima-habu)

A thrombin-like enzyme, named elegaxobin, was purified from the venom of Trimeresurus elegans (Sakishima-habu) by gel filtration on Sephadex G-100, and ion-exchange chromatographies on Q-Sepharose Fast Flow and S-Sepharose Fast Flow. By this procedure, about 8.5 mg of purified enzyme was obtained from 1.1 g of the venom. The purified enzyme showed a single protein band in SDS-polyacrylamide electrophoresis under reducing condition and its molecular weight is 30,000. The specific activity of this enzyme toward tosyl-L-arginine methyl ester (TAME) was 490 TAME units/mg of protein. Elegaxobin clotted only rabbit fibrinogen whereas human and bovine fibrinogens were unaffected. In the fibrinogen-fibrin convertion, the enzyme released only fibrinopeptide A from rabbit fibrinogen, whereas fibrinopeptide B was not released. The N-terminal sequences (Val-Ile-Gly-Gly) of this enzyme was identical to typical sequence of serine proteinases.

Proteases with plasminogen activator activity in hamster oviduct

At present the physiological role of most oviductal proteins remains unknown. In this work, we present evidence that the oviductal secretion as well as the crude oviductal tissue-extract show proteolytic-like esterase and amidase activity. The proteolytic activity of the oviductal enzymes was higher in the oviducts of superovulated hamster females than in those of normal ones, indicating that gonadotrophic hormones would stimulate the synthesis and secretion of these enzymes. Some of their properties were analyzed in the 15,600-g supernatant of both oviductal tissue extracts (OE) and oviductal fluid (OF). The enzymatic activity toward the synthetic substrates p-tosyl-l-arginine methyl ester-HCl (TAME) and alpha-N-benzoyl-dl-arginine-p-nitroanilide HCl (BAPNA) was activated by calcium ions, reached a maximum at pH 7.5, and was inhibited by soybean trypsin inhibitor (SBTI), N-alpha-p-tosyl-l-lysine chloromethyl ketone HCl (TLCK), phenyl methyl sulfonyl fluoride (PMSF), and benzamidine. The OE glycoprotein fraction recognized by WGA-Sepharose affinity columns (37% total proteins) showed proteolytic activity with properties similar to the OE and OF enzymes. The protease activity could be ascribed to a plasminogen activator (PA) detected in the Triton X-100 treated tissue crude membrane fraction (Triton-CMF) and in the oviductal secretion of the superovulated females. In the Triton-CMF fraction, 100% of the proteolytic activity was plasminogen-dependent. The use of amiloride, a selective urokinase-type plasminogen activator (uPA) inhibitor, shows that 90% of this activity was due to a tissue-type plasminogen activator (tPA) and 10% to uPA whereas in the uterus 100% of the activity was tPA. Only a small percentage of the OF proteolytic activity was plasminogen-dependent, probably due to the presence of PA inhibitors in this medium.

A physiological model for tert-amyl methyl ether and tert-amyl alcohol: hypothesis testing of model structures

The oxygenate tert-amyl methyl ether (TAME) is a gasoline fuel additive used to reduce carbon monoxide in automobile emissions. To evaluate the relative health risk of TAME as a gasoline additive, information is needed on its pharmacokinetics and toxicity. The objective of this study was to use a physiologically-based pharmacokinetic (PBPK) model to describe the disposition of TAME and its major metabolite, tert-amyl alcohol (TAA), in male Fischer-344 rats. The model compartments for TAME and TAA were flow-limited. The TAME physiological model had 6 compartments: lung, liver, rapidly perfused tissues, slowly perfused tissues, fat, and kidney. The TAA model had 3 compartments: lung, liver, and total-body water. The 2 models were linked through metabolism of TAME to TAA in the liver. Model simulations were compared with data on blood concentrations of TAME and TAA taken from male Fischer-344 rats during and after a 6-hour inhalation exposure to 2500, 500, or 100 ppm TAME. The PBPK model predicted TAME pharmacokinetics when 2 saturable pathways for TAME oxidation were included. The TAA model, which included pathways for oxidation and glucuronide conjugation of TAA, underpredicted the experimental data collected at later times postexposure. To account for biological processes occurring during this time, three hypotheses were developed: nonspecific binding of TAA, diffusion-limited transport of TAA, and enterohepatic circulation of TAA glucuronide. These hypotheses were tested using three different model structures. Visual inspection and statistical evaluation involving maximum likelihood techniques indicated that the model incorporating nonspecific binding of TAA provided the best fit to the data. A correct model structure, based upon experimental data, statistical analyses, and biological interpretation, will allow a more accurate extrapolation to humans and, consequently, a greater understanding of human risk from exposure to TAME.

Purification from Bothrops lanceolatus (fer de lance) venom of a fibrino(geno)lytic enzyme with esterolytic activity

Bothrops lanceolatus venom has high caseinolytic, phospholipasic, esterolytic and hemorrhagic activities. In spite of having no coagulant effect on plasma, this venom contains a thrombin-like enzyme. Using gel filtration and ion-exchange chromatographies, we have purified an esterolytic fraction (F-II-1a) from this venom with a protein yield of 4% and a 58% recovery in enzyme activity. SDS-PAGE in the presence of beta-mercaptoethanol showed that the enzyme is a single chain polypeptide with a MW=38,100. Immunodiffusion and immunoelectrophoresis of fraction F-II-1a against serum from horses immunized with B. lanceolatus venom and against rabbit antiserum prepared using fraction F-II-1a both showed a single immunoprecipitin line. The Km and Vmax values for TAME hydrolysis were 0.85 mM and 38.6 micromol/min/mg, respectively. The esterolytic activity was completely inhibited by PMSF (10 mM) but not by EDTA (20 mM). Fraction F-II-1a hydrolyzed the alpha and beta chains of fibrinogen. Degradation of the alpha chain occurred within 10 min while that of the beta-chain was slower. The enzyme had no effect on the gamma-chain even after 4 h of hydrolysis.

Basic proteinases from Bothrops moojeni (caissaca) venom--I. Isolation and activity of two serine proteinases, MSP 1 and MSP 2, on synthetic substrates and on platelet aggregation

Two serine proteinases, MSP 1 and MSP 2, were isolated from Bothrops moojeni venom by chromatographies on Sephadex G-100, DEAE-Sephacel (pH 7.5) and SP-Sephadex C-50 (pH 7.5). Both enzymes are basic glycoproteins. On sodium dodecyl sulfate-polyacrylamide electrophoresis, MSP 1 presented two close protein bands corresponding to the mol. wts of 34,000 and 32,500. MSP 2 behaved as a single-chain protein with a mol. wt of 38,000. Specific esterolytic activities of MSP 1 and MSP 2 on alpha-N-tosyl-L-arginine methyl ester (TAME) are 33 mumol min-1 mg-1 and 184 mumol min-1 mg-1, respectively. The most sensitive substrates for the amidolytic activity of both proteinases were the thrombin substrate D-Phe-pipecolyl(Pip)-Arg-4-nitroanilide(Nan) and the glandular kallikrein substrate D-Val-Leu-Arg-Nan. MSP 1, in a concentration of 10(-8) M, causes platelet aggregation in platelet-rich plasma and washed platelets. It also enhances the ADP-induced platelet aggregation. Prostaglandin E1 (PGE1), phenylmethylsulfonyl fluoride (PMSF) and ethylenediamine tetracetic acid (EDTA) abolished completely the aggregation induced by MSP 1. Torresea cearensis trypsin inhibitor (TCTI) inhibited both amidolytic (Ki = 1.96 x 10(-7) M) and platelet-aggregating (Ki = 1.66 x 10(-7) M) activities of MSP 1. The esterolytic activity of MSP 1 and MSP 2 was completely abolished by PMSF, only partially by soybean trypsin inhibitor (SBTI) and benzamidine and not affected by Trasylol. MSP 2 was also inhibited by TCTI (Ki = 0.7 x 10(-7) M).

Inhibition of mediator release during the early reaction to antigen

A nasal lavage model and a new filter paper disk model have been used to measure biologic and physiologic responses to antigen challenge in patients with allergic rhinitis. Pretreatment of subjects with cetirizine reduced the number of sneezes induced by antigen challenge but did not significantly reduce levels of histamine or prostaglandin D2 in a double-blind, placebo-controlled trial with the lavage model. Pretreatment with 60 or 300 mg of terfenadine did significantly reduce levels of histamine, kinin, albumin, and TAME-esterase activity in a double-blind, placebo-controlled study with this model. Again with the nasal lavage model, a double-blind, placebo-controlled comparison of pretreatment with 60 mg of terfenadine or 10 mg of loratadine showed that both agents significantly reduced sneezing. Both drugs also lowered levels of antigen-induced histamine and TAME-esterase, but only terfenadine did so significantly. In a double-blind, placebo-controlled study, the new disk method showed that terfenadine reduced sneezing but not nasal congestion in eight patients with allergic rhinitis. Terfenadine significantly reduced the weight of nasal secretions on both sides of the nose and significantly reduced histamine on the ipsilateral side.

Fibrinolysis relating substances in marine creatures

1. Extracts with physiological saline solution were obtained from about 20 species of invertebrates and seaweed. Tosyl-L-Arg-MeOH hydrolysing and fibrin plate lytic activity were detected in the invertebrates Stichopus japonicus, Crassost gigas, Tapes japonica, and Kintai-gai as well as the seaweed Codiales codium. 2. These activities were all labile against heat (at 65 degrees C for 1 hr). Except for the extract from Stichopus japonicus, lytic activities against fibrin plates with and without plasminogen were similar. 3. The extract from S. japonicus showed plasminogen activating potency as well as the existence of urokinase (UK) activity enhancing factor. 4. On the other hand, the extract of the seaweed Hizikia fusiformis showed a strong UK inhibiting activity. 5. A fraction of fibrinolytic enzyme was obtained from the extract of S. japonicus by absorption to the celite affinity chromatography. It was orally administered to rabbits at a dosage of 40 mg/kg/day. 6. Fibrinolytic activity was determined periodically on the eugloblin fraction of plasma samples collected from these animals. 7. As compared with the pretreatment value, the activity increased about 2 times (P less than 0.01) and 3 times (P less than 0.005) after 4 and 8 weeks, respectively, of the treatment. 8. After 8 weeks of treatment, the kidney of treated rabbits was extracted with 2 M KCl. The activity of tissue plasminogen activator (free-type TPA) was revealed to be enhanced significantly (P less than 0.001) in the extracts. 9. The fibrinolytic enzyme increased in the blood was recognized by zymography to be mainly the UK type plasminogen activator with mol. wt of 53,000.

Replacement of isoleucine-397 by threonine in the clotting proteinase factor IXa (Los Angeles and Long Beach variants) affects macromolecular catalysis but not L-tosylarginine methyl ester hydrolysis. Lack of correlation between the ox brain prothrombin time and the mutation site in the variant proteins

Previously, from the plasma of unrelated haemophilia-B patients, we isolated two non-functional Factor IX variants, namely Los Angeles (IXLA) and Long Beach (IXLB). Both variants could be cleaved to yield Factor IXa-like molecules, but were defective in catalysing the cleavage of Factor X (macromolecular substrate) and in binding to antithrombin III (macromolecular inhibitor). In the present study we have identified the mutation of IXLA by amplifying the exons (including flanking regions) as well as the 5' end of the gene by polymerase-chain-reaction (PCR) method and sequencing the amplified DNA by the dideoxy chain-termination method. Comparison of the normal IX and IXLA sequences revealed only one base substitution (T----C) in exon VIII of IXLA, with a predicted replacement of Ile-397 to Thr in the mature protein. This mutation is the same as found recently for IXLB. The observation that IXLB and IXLA have the same mutation is an unexpected finding, since, on the basis of their ox brain prothrombin time (PT, a test that measures the ability of the variant Factor IX molecules to inhibit the activation of Factor X by Factor VIIa-tissue factor complex), these variants have been classified into two different groups and were thought to be genetically different. Our observation thus suggests that the ox brain PT does not reflect the locus of mutation in the coding region of the variant molecules. However, our analysis suggests that the ox brain PT is related to Factor IX antigen concentration in the patient's plasma. Importantly, although the mutation in IXLA or IXLB protein is in the catalytic domain, purified IXaLA and IXaLB hydrolyse L-tosylarginine methyl ester at rates very similar to that of normal IXa. These data, in conjunction with our recent data on Factor IXBm Lake Elsinore (Ala-390----Val mutant), strengthen a conclusion that the peptide region containing residues 390-397 of normal Factor IXa plays an essential role in macromolecular substrate catalysis and inhibitor binding. However, the two mutations noted thus far in this region do not distort S1 binding site in the Factor IXa enzyme.

Attenuation of allergen sensitivity early in the course of ragweed immunotherapy

During the course of an open immunotherapy (IT) study of ragweed (RW)-allergic patients, nasal mediator release was studied by provocation testing. All subjects had a history of seasonal RW rhinitis, positive skin puncture test to RW, and RW-specific IgE by RAST. Nasal challenge was performed with serial dilutions of RW extract, before and after 12 weekly injections, providing a cumulative dose of 0.22 microgram of Amb a I. Serum IgE and IgG and basophil histamine release with RW were also measured. By 12 weeks of IT, when only 1% of the usual maintenance level dose had been administered, mean histamine release and TAME-esterase activity in nasal washes decreased significantly (p less than 0.05 and p less than 0.01). Prostaglandin D2 release did not change. Skin sensitivity decreased (p less than 0.05), whereas RW-specific IgE increased (p less than 0.05). No significant change in basophil histamine release was observed for RW or a control antigen. Only six of 40 subjects had an RW-specific IgG rise greater than 0.05 microgram/ml. Changes in nasal sensitivity did not correlate with the increases in IgE or IgG or with the change in skin test sensitivity. These present data indicate that there is a significant decline in nasal sensitivity to inhaled RW very early in the course of IT. There is, however, no indication of a relationship between the decreased nasal sensitivity and the production of RW-specific IgG antibodies.

Topical glucocorticosteroids and allergen-induced increase in nasal reactivity: relationship between treatment time and inhibitory effect

The effect of topical glucocorticosteroids on the allergen-induced nasal hyperresponsiveness, with special reference to treatment time, was studied in a double-blind, randomized, placebo-controlled crossover study. Ten patients who previously had shown allergen-induced nasal hyperresponsiveness participated. After pretreatment with either placebo or various periods with topical glucocorticosteroids, they were subjected to an initial challenge with three increasing doses of allergen and were rechallenged after 24 hours with the lowest allergen dose from the previous day. The nasal responses were monitored by means of symptom scores and measurements of N alpha-p-tosyl-L-arginine methyl esterase (TAME) activity in nasal lavages. Five different treatment schedules were used. In the active treatment alternatives, the glucocorticosteroid treatment was started 48, 12 or 2 hours before or 2 hours after the initial allergen challenge. All treatments were continued up to rechallenge on the second day. As the active treatment we used budesonide, 100 micrograms in each nasal cavity every 12 hours. After placebo pretreatment, as expected, there was an increase in nasal symptoms at rechallenge as compared with the initial allergen challenge with the same allergen dose. The mean (+/- SEM) number of sneezes increased from 5.1 +/- 1.7 to 9.5 +/- 2.0 (p less than 0.05), a composite nasal symptoms score increased from 3.3 +/- 0.66 to 4.4 +/- 0.7 (NS), and TAME activity increased from 14.9 +/- 2.83 to 25.3 +/- 0.5 cpm.10(3) (p less than 0.05). Topical glucocorticosteroid treatment abolished this increase in nasal symptoms and TAME activity (p less than 0.05 for all treatment alternatives).(ABSTRACT TRUNCATED AT 250 WORDS)

The cellular response of the human allergic mucosa to natural allergen exposure

It has been suggested that the IgE-dependent late-phase reaction to allergen exposure, with the features of an inflammatory cellular infiltration and airway hyperreactivity, is a link between anaphylaxis and continuous allergic airway disease. Our main knowledge of the cellular response to allergen in sensitized individuals has been derived from allergen-challenge models. To explore the dynamics of the cellular response during the actual disease, patients with a strictly seasonal allergic rhinitis were studied during natural allergen exposure. Ten patients suffering from an isolated birch-pollen allergy were followed from a symptom-free state before, during, and to the height of the birch-pollen season. Repeated parallel cell samplings from the nasal mucosa were performed with cytologic imprints on plastic strips, nasal lavages with the recovery of the cells in the lavage fluid with cytocentrifugation on object slides for cytologic study, and scrapings from the nasal surface with a curette for histologic and ultrastructural evaluation. The histamine content was determined in lavage fluid and cell pellets. The tosyl-alpha-tosyl-L-arginine methyl esterase activity of the nasal lavage fluid was also determined as a biochemical marker of the allergic inflammatory reaction. The birch-pollen season was moderate in terms of pollen counts, and this resulted in mild to moderate nasal symptoms that ran parallel to the birch-pollen counts. The total number of cells recovered in the lavage fluid was 1.2 +/- 0.4 (SEM) x 10(6) before and 3.2 +/- 2.0 per 10(6) cells (not significant) during pollen exposure. Most cells were neutrophils and mononuclear cells.(ABSTRACT TRUNCATED AT 250 WORDS)

The allosteric effect of salt on human mast cell tryptase

The inhibitory effect of potassium chloride and ammonium sulphate on purified human skin tryptase and bovine trypsin was studied enzyme-kinetically, using Z-Gly-Pro-Arg-pNA, Z-Gly-Pro-Arg-AMC, benzoyl-L-arginine ethyl ester (BAEE) and tosyl-L-arginine methyl ester (TAME) as substrates. With increasing salt concentrations, the curve of reaction velocity vs. substrate concentration changed from hyperbolic to sigmoidal when anilide substrates (Z-Gly-Pro-Arg-pNA or -AMC) were used. Only the Km value increased, while the Vmax value remained unchanged. The trend was similar with BAEE or TAME as the substrates. However, the effect of salt on the hydrolysis of these ester substrates was not as strong as on the hydrolysis of anilide substrates, and sigmoidal kinetics were not observed even at the highest KCl concentration (0.7 M) used. Heparin, used as a stabilizer, had no influence on this phenomenon, but it did slightly decrease the apparent Km and Vmax values in low-salt conditions. By comparison, trypsin was not as strongly affected by salt as tryptase, and the inhibition type was mixed competitive and non-competitive. The present results indicate that the salt acts on tryptase as an allosteric effector, and this should be carefully considered when enzyme kinetic parameters and enzyme activity of skin tryptase are measured.

Regulation of human mast cell tryptase. Effects of enzyme concentration, ionic strength and the structure and negative charge density of polysaccharides

Tryptase was previously shown to undergo rapid inactivation under physiological conditions unless stabilized by the presence of heparin. The current study shows that increasing the concentration of free tryptase enhances the preservation of enzymic activity, consistent with dissociation of the tetramer, rather than autodegradation, as the mechanism of inactivation. Heparin glycosaminoglycan fragments of Mr greater than 5700 are necessary for complete stabilization of tryptase activity. This stabilizing effect depends upon negative charge density rather than carbohydrate composition. Thus, keratan sulphate or hyaluronic acid were no better than physiological buffer alone; chondroitin monosulphates and heparan sulphate each prolonged the t1/2 about 20-fold over buffer alone; chondroitin sulphate E prolonged the t1/2 69-fold; and dextran sulphate and heparin provided complete stabilization of tryptase activity for 120 min. Poly-D-glutamic acid prolonged the t1/2 55-fold. In each case the loss of tryptase activity followed apparent first-order kinetics. Increasing the NaCl concentration from 0.01 M to 1.0 M increased the stability of free tryptase. In contrast, increasing the NaCl concentration in the presence of stabilizing polysaccharides decreased the stability of tryptase until dissociation of tryptase from each polysaccharide presumably occurred; thereafter tryptase stability increased as did that of free tryptase. The effect of salt concentration on heparin-stabilized tryptase activity (as opposed to stability) was also evaluated. The mast cell proteoglycans heparin and chondroitin sulphate E, by virtue of containing the naturally occurring glycosaminoglycans of highest negative charge density, may play a major role in the regulation of mast cell tryptase activity in vivo.

Identification and partial purification of a (Na-K)ATPase stimulating serine protease from plasma of insulin-dependent diabetics

Plasma from insulin-dependent diabetics shows an increased ability to specifically activate the (Na-K)ATPase from different sources. Several protease inhibitors like phenyl methyl sulfonyl fluoride, trypsin inhibitor, antithrombin III and aprotinin, produced a significant dose-dependent inhibition of the stimulatory effect produced by a 1/100 final dilution of plasma on the beef heart (Na-K)ATPase activity. Serine proteases employed at scalar concentrations in the ATPase medium gave a dose-dependent stimulation of the enzyme activity as did diabetic plasma. The maximum percent stimulation of the (Na-K)ATPase activity (about 60%) was reached by 0.56 microgram/ml of thrombin, 0.50 microgram/ml of kallikrein and 0.55 microgram/ml of trypsin. The protease-induced ATPase stimulation was significantly reduced by antithrombin III, trypsin inhibitor and by aprotinin. A partial purification of the activating plasma factor was obtained by eluting plasma on a heparin-Sepharose column. Two (Na-K)ATPase stimulating fractions were found, which eluted with 1.0 and 3.0 mol/l NaCl, respectively. Half-maximal stimulation of the enzyme occurred with 3.4 micrograms/ml proteins of fraction 1.0 mol/l and with 45 ng/ml proteins of fraction 3.0 mol/l, this last representing the most purified plasma fraction (about 8890-fold purification). The proteolytic activity of both plasma and purified plasma fractions was tested on Tos-Arg-OMe substrate which was hydrolyzed to a much higher degree by the most purified plasma fraction. Like the (Na-K)ATPase stimulation, the esterolytic activity was inhibited by protease inhibitors, the most effective to this regard being antithrombin.

Hyposmotic swelling leads to the expression of trypsin-like activity by rat peritoneal fluid mast cells

Rat peritoneal fluid mast cell present parallel increases in cell area (swelling), and in hydrolytic activity on the trypsin substrate p-tosyl arginine methyl ester (TAME), when placed in Tris buffers of concentrations between 0.15 and 0.03 M. Under these conditions, cells do not degranulate and preserve their trypsin-like enzyme activity after low speed centrifugation. Exposure to more dilute Tris buffers, between 0.015 and 0.003 M, leads to cell rupture accompanied by progressive degranulation and loss of activity on TAME. Protamine, a heparin antagonist prevented this loss when added to mast cells prior to hyposmotic lysis, or lysis by sonication or repeated periods of freezing and thawing. Enzyme activity released in the presence of protamine was fully recovered in supernates of cell lysates submitted to low speed centrifugation. Controlled swelling of mast cells propitiates the expression of trypsin-like activity, possibly by facilitating enzyme-substrate interaction. Cell lysis on the contrary, leads to inactivation of such activity, possibly by enzyme binding to heparin in exposed mast cell granules.

New synthetic inhibitors of chymotrypsin

4-Substituted carbonylphenyl ester derivatives were prepared and their inhibitory effects on chymotrypsin, trypsin, thrombin, plasmin, pancreatic kallikrein, and plasma kallikrein were examined. Among the various inhibitors tested, 4-[2-(dimethylamino)ethylaminocarbonyl]phenyl 1,2,3,4-tetrahydro-1-naphthoate hydrochloride (FK-316), 4-[(2-[4-pyrrolidinocarbonylmethyl)oxycarbonyl]-phenyl 5-methoxyindole-3-acetate dihydrochloride (FK-375), 4-[(2-[4-(piperidinocarbonylmethylpiperadino]ethyl)oxycarbonyl+ ++]phenyl 1-naphthylacetate dihydrochloride (FK-386), 4-[(2-[4-(2-[morpholino]ethyl)piperadino]ethyl)oxycarbonyl]p henyl 5-methoxy-2-methylindole-3-acetate trihydrochloride (FK-401) and 4-(4-isopropylpiperadinocarbonyl)phenyl 1,2,3,4-tetrahydro-1-naphthoate methanesulfonate (FK-448) were the most effective and specific inhibitors of chymotrypsin.

Subunit interactions of 7 S nerve growth factor. Gamma-esterase activity, rates, and conformational changes during reassociation

The gamma-esterase activity of 7 S nerve growth factor (NGF) is depressed relative to free subunit because of constraints within the oligomer. 4 M urea causes a reversible dissociation of 7 S NGF and concomitant increase in esterase activity. The gamma-esterase activity with tosyl-arginyl-methyl-ester increased between 1 and 4 M urea and was inhibited at higher concentrations. Upon dilution of 7 S NGF from 6 M urea, the esterase activity was initially identical with that of the similarly treated gamma-subunit but decayed rapidly (10 min) to approach that of the native 7 S NGF. In the presence of 100 microM EDTA the activity was higher, but still required the same length of time to reach a constant depressed value. Upon dilution of 7 S NGF from 2 M NaCl the rapid decay was not observed and the activity remained constant at about the same level as the equilibrium values for the urea-treated and renatured 7 S NGF. A red shift in the fluorescence maximum and a concomitant increase in quantum yield occurred for the 7 S in 8 M urea. Dilution into buffer resulted in a rapid decay and return to native 7 S fluorescence but not when EDTA was included. Both the decay in esterase activity and in fluorescence intensity upon dilution from urea were first order reactions with a rate constant of about 8 X 10(-3) s-1 suggesting that both methods were measuring a unimolecular renaturation process. Renaturation from NaCl or recombination of isolated subunits was much more rapid, indicating a simple combination of subunits in a native conformation. The circular dichroism spectra of urea and NaCl-treated 7 S NGF were different, and spectra of the renatured species with and without EDTA differed. Reassociation to a conformationally different 7 S NGF probably occurs in the presence of EDTA. The results emphasize the role of zinc in 7 S NGF formation and the influence of conformational changes in the effect of beta-NGF on the activity of the gamma-esterase in 7 S NGF.

Characterization of a trypsin-like protease from the bacterium Bacteroides gingivalis isolated from human dental plaque

A trypsin-like, membrane-bound protease from Bacteroides gingivalis was solubilized by Triton X-100 and partially purified by a combination of DEAE-Sepharose and aminophenylmercuric Sepharose chromatography, by taking advantage of the thiol group on the enzyme. The purified enzyme hydrolysed the synthetic substrates benzoyl-L-arginine-p-nitroanilide (L-BAPA), benzoyl-D,L-arginine-beta-naphthylamide (BANA) and tosyl-L-arginine methyl ester, as well as bovine serum albumin and ovalbumin, but not tosyl-L-lysine methyl ester. The enzyme activity was enhanced by SH-reagents and was inhibited to different degrees by SH-inhibitors, chelators and microbial low-molecular-weight inhibitors such as leupeptin, antipain and chymostatin. These microbial inhibitors could be of practical use as ligands for affinity chromatography for further purification. The possible involvement of the protease in periodontal diseases is also discussed.

Enzymic activity of thrombin with partially reduced disulfide bonds

Partial reduction of thrombin disulfide bridges with dithiothreitol in the absence of denaturants inhibits the fibrinogen clotting but not the esterase activity of the enzyme. The clotting activity reappears on spontaneous air reoxidation of thrombin. As a result of the reaction with dithiothreitol, two disulfide bonds are cleaved in thrombin molecule inducing a small decrease of beta-sheets in the secondary structure of thrombin. It may be concluded that this modification does not affect the catalytic site of thrombin but has influence upon the fibrinogen binding (recognition) site.

Radiation-induced changes in purified prothrombin and thrombin

The effect of gamma-irradiation on purified prothrombin and thrombin in aqueous solution has been assessed with reference to bifunctional activities, e.g., clotting and esterase functions, physico-chemical changes in structure, and kinetics. The inactivation curves indicated that the clotting activity was more susceptible to gamma-radiation than the esterolytic function in both the proteins. Prothrombin was comparatively more sensitive to radiation than thrombin. The irradiation of prothrombin (100 kR) caused modifications in the protein resulting in reduced formation of thrombin after activation by Factor Xa. The modifications caused by irradiation were assessed in these proteins by changes in spectral characteristics, levels of tryptophan and disulphides, electrophoretic mobility and amino acid composition. Radiation-induced changes in thrombin were reflected in its kinetic behaviour. The clotting activity of thrombin was almost completely lost at 100 kR, while esterolysis was relatively less affected. The modification of tyrosine and tryptophan residues in thrombin influenced the clotting activity, while these were not involved for esterolysis. Histidine had involvement in both these activities.

Assay of prekallikrein in human plasma: comparison of amidolytic, esterolytic, coagulation, and immunochemical assays

Using the substrate H-D-Pro-Phe-Arg-p-nitroanilide-HCl, an amidolytic assay was designed to measure prekallikrein in plasma. At a substrate concentration of 1 mM (Km = 0.2 mM), the amidolysis of purified kallikrein at 1 coagulant unit/ml was observed to be 2.47 mumole/min/ml. Conditions for plasma prekallikrein activation were optimized to approach complete activation when compared to the amidolytic activity of the purified plasma kallikrein. Plasma treated with chloroform to destroy inhibitors of kallikrein was activated with dilute kaolin (final concentration 1 mg/ml) for 1 min at 25 degrees C. Activated plasma prekallikrein had 78% (1.92 mumole/min/ml) of activity of purified kallikrein at plasma concentration. Comparison of this amidolytic assay with immunochemical, esterolytic, and coagulant assays of three subject populations (normals, women on birth control pills, and patients with hepatocellular disease) showed good correlation both in normals and in the patient groups between the amidolytic and esterolytic assays (r = 0.89). Each enzymatic assay correlated with the immunochemical assay (r = 0.72, r = 0.68, respectively). However, comparison of each of these assays with the coagulant assay showed no significant correlation due to the large inherent error of the latter assay. This standardized plasma prekallikrein amidolytic assay should facilitate studies of plasma prekallikrein concentration in physiologic and pathologic conditions and help identify activation of the contact phase of coagulation in disease states.

Studies on the activation mechanism of fibrinolytic enzyme system in plasma by human pancreatic elastase

In the present study, the activation mechanism of fibrinolytic enzyme system in plasma by human pancreatic elastase was investigated. It was confirmed that human pancreatic elastase not only converted the co-existing plasminogen to low molecular weight-plasminogen which could be easily activated by the activator, but also inhibited alpha 2-macroglobulin and alpha 2-plasmin inhibitor which are antiactivators or fast reacting antiplasmins, and consequently, induced the activation of the fibrinolytic enzyme system in plasma.

Trypsin inactivation by intact Hymenolepis diminuta (Cestoda): some characteristics of the inactivated enzyme

In the presence of intact Hymenolepis diminuta, trypsin was inactivated; intact worms had no apparent effect on subtilisin, pepsin, or papain. Inactivation of trypsin was demonstrable using azoalbumin as a substrate, but the inactivated enzyme retained full catalytic activity against benzoyl-DL-arginine-p-nitroanilide, p-tosyl-L-arginine methyl ester (low molecular weight synthetic trypsin substrates) and p-nitro-p-guanidinobenzoate (an active site titrant). Inactivation was not reversible under conditions of heating, freezing and thawing, or prolonged dialysis of the enzyme. Analyses of inactivated 3H-trypsin by cationic and SDS-polyacrylamide gel electrophoresis, and gel chromatography failed to indicate the presence of a high molecular weight trypsin inhibitor associated with the inactivated enzyme; no low molecular weight, dissociable inhibitor was demonstrable following thermal denaturation of the inactivated enzyme. Analyses of trypsin after incubation in the presence of pulse-labeled worms also failed to demonstrate the presence of any inhibitor of worm origin associated with the inactivated enzyme. The data suggest that inactivation is the result of a small structural or conformational change in the enzyme molecule, a change which partially (rather than totally) inactivates the enzyme towards protein substrates.

The radioimmunoassay of human urinary kallikrein and comparisons with kallikrein activity measurements

Human urinary kallikrein was purified to homogeneity, and an antiserum to it was raised in rabbits. A RIA was devised which uses this rabbit antiserum (Keq = 2.75 x 10(11) M-1) in a final dilution of 1:2,500,000 and the purified kallikrein labeled with 125I using a lactoperoxidase method. Assay sensitivity is 8 pg kallikrein. Thus far, the assay is specific for human and perhaps monkey urinary kallikrein. Correlations between this assay of immunoreactive kallikrein and the alpha-N-Tosyl-L-arginine-[3H]methylester (Tos-Arg-OMe) activity method or a kininogenase assay were highly significant (r = 0.94 and 0.96, respectively) and show that each assay measures human urinary kallikrein comparably. Low or high dietary sodium intakes, maneuvers known to change human urinary Tos-Arg-OMe esterase excretion, change immunoreactive kallikrein to an equivalent degree. Normal black children, already known to excrete significantly less Tos-Arg-OMe esterase than white children, excrete similarly reduced amounts of immunoreactive kallikrein. Kallikrein excretion in children with cystic fibrosis of the pancreas was not different from that in normal children. The data show that a specific and sensitive direct RIA for human urinary kallikrein has been developed and that both the Tos-Arg-OMe esterase and kininogenase assays measure human urinary kallikrein activity specifically, at least in the described circumstances.

Basophil mediators and their release, with emphasis on BK-A

During IgE-mediated events, basophils secrete small molecular weight mediators (histamine, slow reacting substance, Eosinophil chemotactic factor) which are thought to participate in inflammatory processes. We here describe the IgE-mediated secretion of large molecular weight mediators which have the potential for the activation of the Hageman factor dependent pathways, and the generation of biologically active peptides. These large molecular weight basophil derived mediators may, through the activation of the Hageman factor dependent pathways, influence mechanisms which participate in both acute and chronic cell-mediated inflammatory processes. We suggest that these proteases may participate not only as mediators of the immediate hypersensitivity reaction, but may also function in important aspects of the entire inflammatory response.

Influence of coagulation on the activation of plasminogen by streptokinase and urokinase

Human plasma was mixed with Ca++ or thrombin, and urokinase (UK) or streptokinase (SK) and a chromogenic substrate (S-2251: H-D-Val-Leu-Lys-pNA) specific to plasmin. The hydrolysis of S-2251 was higher when clot was formed by the addition of Ca++ or thrombin than in the absence of clot. The hydrolysis of S-2251 by euglobulin in the presence of UK was also higher when clot was formed, thus, inhibitors may not be related to the better activation of plasminogen, in the presence of fibrin clot. It may be suggested that plasminogen was better activated by activators (UK and SK) in the clot than in its absence.

A direct radioimmunoassay of rat urinary kallikrein and comparison with other measures of urinary kallikrein activity

A highly sensitive radioimmunoassay for rat urinary kallikrein (minimal detectable amount, 40 pg/tube) has been developed. The assay uses a sheep antibody (Keq = 3.25 X 10(10)M-1) against purified Sprague-Dawley rat urinary kallikrein in a final dilution of 1 : 1,200,000. The assay incorporates a convenient and inexpensive PEG technique for separation of free from bound antigen. Parallel standard curves with rat urine or kidney homogenates were obtained. No cross-reactivity with human or dog urine samples or purified human urinary kallikrein was seen. Correlations among this assay, an esterolytic method, and a kininogenase radioimmunoassay for kallikrein were highly significant, with only the esterolytic assay demonstrating any significant nonspecificity. The radioimmunoassay can detect changes in urinary kallikrein levels produced by a maneuver known to alter urinary kallikrein excretion.

Preparation and some properties of human serum kallikrein immobilized on ARM-Sepharose

A highly purified human serum kallikrein immobilized on CH-Sepharose 4-B was obtained. KM values for N-benzoyl-L-arginine ethyl ester and N-tosyl-L-arginine methyl ester hydrolysis of this preparation were 1.10 x 10(-3) M and 3.6 x 10(-4) M, respectively; pH optimum of hydrolysis of these esters were found to be 8.2 and 8.5, respectively. The immobilized kallikrein possessed kininogenase activity and was capable of activating prekallikrein.

Inhibition of esterase and amidase activities of alpha- and beta-thrombin in the presence of antithrombin III and heparin

Inhibition of the esterase and amidase activities of bovine alpha- and beta-thrombin in the presence of antithrombin III and heparin has been studied. It was found that both the esterase and amidase activities of alpha-thrombin were inhibited by antithrombin III and the reactions were accelerated by heparin. The inhibition of amidase and esterase activities of beta-thrombin by antithrombin III has also been demonstrated. Heparin however did not increase the rate of inactivation of the enzyme.

Modes of inhibition of activities of trypsin and chymotrypsin by potassium thiocyanate

Potassium thiocyanate inhibited the activities of trypsin and chymotrypsin. The inhibition was mixed type on both enzymes with casein as substrate and on trypsin with tosyl-L-arginine methyl ester as substrate, but was uncompetitive on chymotrypsin with benzoyl-L-tyrosine p-nitroanilide as substrate.

Effects of gentamicin on trypsin, chymotrypsin, and collagenase

The effects of gentamicin on three proteolytic enzymes were studied. Gentamicin was tested at concentrations of 0.5-500 microgram/ml. Trypsin was tested at 0.5 microgram/ml using p-tosyl-L-arginine methyl ester and at 0.1 and 0.5 microgram/ml using azocoll as the substrate. Chymotrypsin was tested at 0.1 and 0.5 microgram/ml with azocoll. A soluble [14C]collagen assay was used to measure activity of collagenase derived from Clostridium histolyticum. The profiles of proteolytic activity vs. gentamicin concentration were similar for all three enzymes. At lower concentrations of gentamicin (less than 70 microgram/ml), there were two peaks of enhanced protease activity generally followed by inhibition. These unusual multiphasic effects of gentamicin on three different proteases are not presently understood, but they imply a previously unreported mode of action for this antibiotic.

The two human trypsinogens: catalytic properties of the corresponding trypsins

The catalytic properties of the two human trypsins obtained from purified trypsinogens have been studied. The catalytic rate constant kcat and the pK of the ionisable residue implicated in the active site have been determined with Bz-Arg-OEt. The hydrolysis of Tos-Arg-OMe by human trypsins does not follow the simple Michaelis-Menten scheme and indicates a difference in the conformational flexibility of the active site-regions of the two enzymes. Both enzyme are readily autolyzed and calcium ion plays a fundamental role in stabilizing trypsin activity. However trypsin 2 self-digests more rapidly than trypsin 1. These results are a prerequisite to the elucidation of the fate of pancreatic enzymes in human digestive tract.

The effect of bile salts on the esterolytic assay of trypsin

A bile salt mixture and pure sodium taurocholate were each shown to increase the esterolytic activity of trypsin in aqueous solution and in intestinal juice. rho-Toluene-sulphonyl-L-arginine methyl ester (TAME) was used as a substrate, and both a spectrophotometric and a potentiometric assay system were used. The maximal potentiation of the esterolytic activity of trypsin by bile salts was about 1.6 to 2.2 times the activity without bile salts (depending on the assay conditions and whether the trypsin was in aqueous solution or intestinal juice). The proteolytic activity of trypsin was decreased by the addition of bile salts. It seemed likely, therefore, that the potentiating effect of bile salts on trypsin esterolytic activity is primarily on the substrate (TAME) rather than trypsin itself. It was thought that TAME might be taken up into bile salt micelles and thus be more readily hydrolysed by trypsin, but we were unable to substantiate this hypothesis. The precision of the trypsin esterolytic assay was better when bile salts were not added. If however bile salts were to be used routinely in the trypsin assay, it would be useful to ensure that the concentration of calcium, included as activator, is sufficiently low to prevent the formation of a precipitate. This precipitate is probably a complex of calcium and bile salts.

Normal plasma arginine esterase and the Hageman factor (factor XII) -prekallikrein-kininogen system in cystic fibrosis

Previous investigators have suggested that the biological activity of plasma prekallikrein is defective in cystic fibrosis. In contrast, no such difference was demonstrable between normal and cystic fibrosis plasma. Esterolytic activity for the synthetic substrate p-toluene sulfonyl-arginine methyl ester (TAMe) evolved normally in cystic fibrosis plasma treated with chloroform and ellagic acid, a measure of generation of plasma kallikrein. Additionally, plasma prekallikrein (Fletcher factor) and high molecular weight kininogen (Fitzgerald factor), a substrate of plasma kallikrein, were normal. Thus, the concept that cystic fibrosis is associated with abnormalities in the plasma kallikrein-kinin system could not be supported.

Proteolysis of tropoelastin

The presence of an enzyme associated with tropoelastin is described. The enzyme has a pH optimum between 7 and 9 and trypsin-like specificity. Upon incubation, tropoelastin (72,000 molecular weight) is cleaved into relatively high molecular weight fragments. In addition to the parent molecule, five discrete polypeptide bands are usually observed on SDS gels with molecular weights of approximately 57,000, 45,000, 36,000, 25,000 and 13-14,000.