(Z)-7-Chloro-3-[(3-chlorophenyl)-methylidene]-4-p-tosyl-3,4-dihydro-2H-1,4-benzoxazine

In the title compound, C22H17Cl2NO3S, the molecule is a substituted 3,4-dihydro-2H-1,4-benzoxazine compound which has three phenyl rings which are essentially planar. The 3,4-dihydro-2H-oxazine part of the molecule is fused to the benzo ring and has a half-boat conformation; the dihedral angle between the planar part of the oxazine ring and the benzo ring is 10.2 (2) degrees. The (3-chlorophenyl)methylidene substituent has a Z configuration in relation to the ring N atom of the oxazine moiety. Interestingly, the p-toluenesulfonyl (p-tosyl) substituent on the ring N atom protrudes away from the 3-chlorophenyl substituent thus avoiding any steric interaction.

Photochemistry of Tosylstilbenoids in the Preparation of Complex Heterocyclic Compounds. Synthesis of a Cyclopropafuroindolone Analogue of the DNA-Alkylating Section of the Antitumor Compound CC-1065

[reaction in text] A novel photocyclization of tosylstilbenoids is used in the preparation of a cyclopropafuroindolone analogue of the DNA-alkylating unit of the antitumor compound CC-1065.

Chloramine-T in radiolabeling techniques. IV. Penta-O-acetyl-N-chloro-N-methylglucamine as an oxidizing agent in radiolabelling techniques

Chloramine-T (CAT) is commonly used in radiolabeling of bioactive molecules by halogenation. CAT is used to release radioactive elemental iodine by oxidation of its salts. Unfortunately, CAT is a strong oxidizing agent and can cause significant damage to peptides and proteins. This may lower the yield of the iodination reaction and may produce undesirable side products. Recently, it was found that the in situ formation of N-chlorosecondary amines, by the addition of secondary amines to CAT prior to exposure to the substrate, can reduce the oxidative damage caused by CAT. To simplify the method, we prepared penta-O-acetyl-N-chloro-N-methylglucamine (NCMGE) as a solid N-chlorosecondary amine. The chemical reactivity of NCMGE toward a model amino acid, 1-aminocyclohexane carboxylic acid, was compared with that of chloramine-T. In the presence of the model amino acid, CAT lost all its chlorine titer within 60 min while NCMGE retained 99% of its chlorine titer. NCMGE was compared to CAT for the iodination of l-tyrosine and leucine enkephalin. For both substrates, the NCMGE method produced larger or equal yields of the monoiodo and diiodo products and less decomposition. It is proposed that the method employing NCMGE to release diatomic iodine is more convenient and efficient for radiolabeling peptides and proteins than currently used methods.

1,2-Diphenyl-2-(phenyldiazenyl)-2-tosylethanone, an example of a fungicide containing a sulfonyl group

The molecule of the title compound, C(27)H(22)N(2)O(3)S, adopts an irregular propeller shape with the tetrahedral C1 atom pivotal. The alpha-azophenyl and alpha-phenyl moieties are approximately coplanar. Electrostatic attraction of the oppositely charged atoms generates several short intramolecular contacts involving the sulfonyl, azo and carbonyl groups. Characteristic bond-length distribution of the central part of the molecule indicates that the Coulombic charge transfer is supplemented by hyperconjugation involving donation of electron density from the azo moiety towards the sulfonyl and carbonyl groups.

The synthesis and fluorescent properties of analogues of the zinc(II) specific fluorophore zinquin ester

The synthesis and fluorescent properties in the absence and presence of zinc(II) of a range of 2-substituted derivatives of N-(6-methoxy-2-methyl-8-quinolyl)-4-methylbenzenesulfonamide are described. These analogues formed complexes with zinc(II) as indicated by a bathochromic shift in their UV/vis spectra. Analogues with isobutenyl and isobutyl side chains at the 2-position formed fluorescent complexes whose fluorescence was stronger than that of the 2-methyl-containing parent. These derivatives were converted, via conversion to the phenol with boron tribromide and reaction with ethyl bromoacetate, to systems with ester-containing side chains analogous to zinquin ester, a specific cellular fluorophore for zinc(II). All of these ester derivatives formed complexes with zinc(II) resulting in a bathochomic shift in their UV/vis spectra. Compounds with isobutyl, isobutenyl, and styryl side chains exhibited increased fluorescence compared to that of zinquin ester in the presence of zinc(II). The compound with the 2-isobutyl side chain was more selective in its fluorescence for zinc(II) over cadmium(II) compared to zinquin ester.

Reaction of 2-bromomethylazoles and TosMIC: A domino process to azolopyrimidines. Synthesis of core tricycle of the variolins alkaloids

A new reaction of N-protected 2-bromomethylazoles and tosylmethyl isocyanide (TosMIC) leading to the preparation of azolopyrimidines is described. This domino sequence was used to synthesize the pyrido[3',2':4,5]pyrrolo[1,2-c]pyrimidine core of alkaloids variolins from 4-methoxy-2-methylpyrrolo[2,3-b]pyrimidine in two steps.

4-toluenesulfonylureido derivatives of amines, amino acids and dipeptides: a novel class of potential antitumor agents

The screening of a series of arylsulfonylureido derivatives of amines (such as histamine, or dopamine), aliphatic/aromatic amino acids (such as Gly, beta-Ala, Val, Lys, Arg, Phe, Tyr, DOPA, etc.) and dipeptides (such as GlyGly, beta-AlaHis) led to the identification of three derivatives that possess tumor growth inhibitory properties against several leukemia, non-small cell lung, ovarian, melanoma, colon, CNS, renal, and breast cancer cell lines in vitro. The new derivatives were prepared by reaction of 4-toluenesulfonyl isocyanate with (protected) amines, amino acids or dipeptides. The mechanism of antitumor action with these new derivatives is not known at the moment but it may imply uncoupling of mitochondria, as for the structurally related diarylsulfonylurea sulofenur, an investigational anticancer agent.

Modeling solid-to-solid biocatalysis: integration of six consecutive steps

A quantitative model for the conversion of a solid-substrate salt to a solid-product salt in a batch bioreactor seeded with product crystals is presented. The overall process consists of six serial steps (with dissolution and crystallization each in themselves complex multistep processes): solid-salt dissolution, salt dissociation into an ionic substrate and a counter-ion, bioconversion accompanied by biocatalyst inactivation, complexation of the ionic product with the counter-ion, and salt crystal growth. In the model, the consecutive steps are integrated, including biocatalyst inactivation and assuming that salt dissociation and complexation of ions are at equilibrium. Model parameters were determined previously in separate independent experiments. To validate the model, either dissolved or solid Ca-maleate was converted to solid Ca-D-malate by permeabilized Pseudomonas pseudoalcaligenes in a batch bioreactor seeded with Ca-D-malate crystals. The model very well predicted the concentrations of all components in the liquid phase (Ca-maleate, Ca(2+), maleate(2-), D-malate(2-), and Ca-D-malate) and the amounts of the solid phases (Ca-maleate. H(2)O and Ca-D-malate. 3H(2)O), especially when high initial amounts of Ca-maleate. H(2)O and Ca-D-malate. 3H(2)O were present.

(E)-2-[2-(1-Naphthyl)vinyl]-3-tosyl-2,3-dihydro-1,3-benzothiazole

The title compound, C(26)H(21)NO(2)S(2), which consists of a benzothiazole skeleton with alpha-naphthylvinyl and tosyl groups at positions 2 and 3, respectively, was prepared by palladium-copper-catalyzed heteroannulation. The E configuration of the molecule about the vinyl C=C bond is established by the benzothiazole-naphthyl C-C-C-C torsion angle of 177.5 (4) degrees. The five-membered heterocyclic ring adopts an envelope conformation with the Csp(3) atom 0.380 (6) A from the C(2)NS plane. The two S-C [1.751 (4) and 1.838 (4) A] and two N-C [1.426 (5) and 1.482 (5) A] bond lengths in the thiazole ring differ significantly.

An investigation of imidazole and oxazole syntheses using aryl-substituted TosMIC reagents

This article describes efficient and mild protocols for preparing polysubstituted imidazoles in a single pot from aryl-substituted tosylmethyl isocyanide (TosMIC) reagents and imines generated in situ. Traditional imine-forming reactions employing virtually any aldehyde and amine followed by addition of the TosMIC reagent delivers 1,4,5-trisubstituted imidazoles with predictable regiochemistry. Employing chiral amines and aldehydes, particularly those derived from alpha-amino acids, affords imidazoles with asymmetric centers appended to N-1 or C-5 with excellent retention of chiral purity. 1,4-Disubstituted imidazoles are also readily prepared by a simple variant of the above procedure. Selecting glyoxylic acid as the aldehyde component of this procedure leads to intermediates such as 48, which readily undergo decarboxylation and elimination of the tosyl moiety to deliver 1,4-disubstituted imidazoles in high yields. Alternatively, using NH(4)OH as the amine component in conjunction with a variety of aldehydes delivers 4, 5-disubstituted imidazoles in moderate to good yields in a single pot while avoiding the need for protecting groups. Finally, the facile preparation of mono- and disubstituted oxazoles from these TosMIC reagents and aldehydes is described.

Efficient synthesis of carbocyclic nucleoside, (+/-)-homocarbovir via pi-allylpalladium complex formation from the allyl-N,N-ditosylimide substrate

The synthesis of a carbovir analogue, (+/-)-homocarbovir (3) was achieved from norbornadiene (4) in seven steps and 27% overall yield. This route involves a Meinwald-type rearrangement, an acid-hydrolysis of N-tosyl bicyclic enamine 5, and a Pd(0)-catalyzed coupling reaction.

[Tanfelam: synthesis, study of ovicidal activity, and acute toxicity]

The papers describes the synthesis of N-(2-piperidinoethyl)-N-tosyl-n-anisidine (Tanfelam) which showed a 100% ovicidal activity when tested by the Harada and Mori methods (in vitro inhibited N.brasiliensis hatching and development test). Tanfelam has been transferred for in-depth tests.

The chemical cell biology of zinc: structure and intracellular fluorescence of a zinc-quinolinesulfonamide complex

Fluorescent cell-permeant compounds based on 6-methoxy-8-p-toluenesulfonamido-quinoline, TSQ, are potentially powerful probes of intracellular zinc chemistry; however, the structure, thermodynamics, and stoichiometry of the metal complexes, and the molecular basis of Zn(II) recognition, remain open issues. To address these, we report the first structural characterization of a Zn(II) complex of a TSQ derivative, namely 2-methyl-6-methoxy-8-p-toluenesulfonamido-quinoline (3) and describe its unusual coordination chemistry. The crystal structure of the fluorescent complex of 3 with zinc reveals a 2:1 stoichiometry wherein bidentate coordination of two nitrogens from each ligand gives rise to a highly distorted tetrahedral Zn(II) center. Both sulfonamido groups in the zinc complex are tilted away from zinc to make room for coordination of the amide nitrogens. Zn-O(2) and Zn-O(4) distances are essentially nonbonding (3.06 and 3.10 A, respectively). The bond angles [N(1)-Zn-N(2) 83.5 degrees and N(3)-Zn-N(4) 83.0 degrees] are quite small relative to the 109 degrees angle of an ideal tetrahedral center. This result provides an insight into the zinc-binding mode of the TSQ derivative zinquin, in which a methyl group replaces the hydrogen in the 2-position of the quinoline ring. The methyl group and sulfonamide oxygen atoms clearly hinder formation of both square planar and octahedral complexes. We also show here that the Zn(II) complex of 3 in DMSO-water (80/20 w/w) exhibits an overall binding stability (log beta 2 = 18.24 +/- 0.02) similar to zinquin. Fluorescence microscopy suggests that each of these members of this family demarks a similar set of Zn(II)-enriched compartments that are common to all eukaryotic cells examined to date, and further shows that the ester function is not required for observation of these ubiquitous Zn-loaded compartments. The combined structural, thermodynamic, and physiological results provide a basis for design of other Zn(II)-specific membrane permeant probes with a range of Zn(II) affinities and photophysical properties.

High yield direct 76Br-bromination of monoclonal antibodies using chloramine-T

Monoclonal antibody (MAb) A33 was labeled with the positron emitter 76Br (T(1/2) = 16.2 h). Direct labeling was done using the conventional chloramine-T method. After optimization of the labeling conditions, a maximum yield (mean +/- max error) of 77 +/- 2% was obtained at pH 6.8. In vitro binding of 76Br-A33 to SW1222 colonic cancer cells showed that the immunoreactivity was retained. Also, the MAbs 38S1 and 3S193 and the peptide hEGF were 76Br-labeled, resulting in labeling yields (mean +/- max error) of 75 +/- 3%, 63 +/- 4%, and 73 +/- 0.1%, respectively. We conclude that antibodies and peptides can be labeled conveniently with 76Br for the purpose of whole-body tumour imaging by positron emission tomography.

Tert-butylsulfonamide. A new nitrogen source for catalytic aminohydroxylation and aziridination of olefins

[reaction: see text] The N-chloramine salt of tert-butylsulfonamide has been shown to be an efficient nitrogen source and the terminal oxidant for catalytic aminohydroxylation and aziridination of olefins, resembling closely Chloramine-T by its behavior in these catalytic reactions. The sulfonyl-nitrogen bond in the product or its derivatives is easily cleaved under mild acidic conditions, allowing for facile liberation of the amino group.

Chloramine-T in high-specific-activity radioiodination of antibodies using N-succinimidyl-3-(trimethylstannyl)benzoate as an intermediate

Monoclonal antibodies C215 and MOv18 have been radiohalogenated, using a single-batch method employing N-succinimidyl-3-(trimethylstannyl)benzoate, m-MeATE. Labelling to the stannyl ester was optimized using chloramine-T as oxidizing agent. The results show that the stannyl ester is effectively labelled with short reaction times giving reproducible yields from 85% to 95%. Subsequent antibody conjugation, 10 to 80 microg MAb, resulted in biologically active, labelled antibodies with overall radiochemical yields of 50% to 80%, with corresponding specific activities of 490-50 kBq(125I)/microg.

N-carbamoyl analogs of Zafirlukast: potent receptor antagonists of leukotriene D4

Exploration of the indole nitrogen region of Zafirlukast (1) has uncovered a potent series of cysteinyl leukotriene D4 (LTD4) antagonists. These studies showed that a variety of functionality could be incorporated in this region of the molecule without sacrificing potency. Efforts to exploit this site in order to improve oral efficacy are discussed.

Carbonic anhydrase inhibitors: inhibition of isozymes I, II and IV with N-hydroxysulfonamides--a novel class of intraocular pressure lowering agents

A series of N-hydroxy sulfonamides has been prepared by reaction of alkyl-, arylalkyl- and arylsulfonyl halides or sulfonic acid anhydrides with hydroxylamine. Structurally related inhibitors were also obtained from acyl chlorides and hydroxylamine, as well as by reaction of tosyl isocyanate with hydroxylamine, sulfamic acid and sulfamide. Inhibition of three carbonic anhydrase (CA) isozymes, hCA I, hCA II and bCA IV (h = human; b = bovine) with the prepared compounds has been investigated. Good inhibitors, as well as compounds with moderate activity against these isozymes were detected, depending on the R group to which the SO2NHOH or CONHOH moieties were attached. Susceptibility to inhibition was generally: hCA II > bCA IV >> hCA I. Some of the new inhibitors showed very good antiglaucoma action when administered directly into the eye in experimental animals, acting as more efficient intraocular pressure lowering agents as compared to the clinical drug dorzolamide. This constitutes an encouraging result for obtaining novel antiglaucoma drugs from this class of CA inhibitors.

Chloramine T-induced structural and biochemical changes in echistatin

Echistatin is a member of the disintegrin family of peptides and a potent inhibitor of platelet aggregation and cell adhesion. Echistatin binds to integrin alpha(v)beta3 and alpha(IIb)beta3 receptors with high affinity. Binding is mediated by an RGD-containing loop maintained in an appropriate conformation by disulfide bridges. In this study, we have compared the binding characteristics of echistatin iodinated by either lactoperoxidase or chloramine T method. We show that echistatin labeled by lactoperoxidase method binds to integrin alpha(v)beta3 receptor with high affinity and in a non-dissociable manner very similar to native echistatin. In contrast, chloramine T-labeled echistatin can rapidly dissociate from the receptor. We demonstrate that chloramine T reaction results in the addition of an extra oxygen to the methionine residue adjacent to the RGD motif in echistatin. Modeling studies and molecular dynamic simulation studies show that the extra oxygen atom on the methionine residue can form hydrogen bonds with the glycine and aspartic acid residues of the RGD motif. These structural changes in echistatin help explain the changes in the binding characteristics of the molecule following chloramine T reaction.

Chemistry and structure--activity relationships of leukotriene receptor antagonists

Several strategies have been employed by medicinal chemists in the design of potent and selective leukotriene receptor antagonists-leukotriene structural analogs, FPL 55712 analogs, and random screening of corporate compound banks. Lead compounds were optimized, often through the exchange of ideas with groups working on other chemical series of leukotriene antagonists. Pranlukast can likely be traced to a lead compound identified by random screening that was initially modified by incorporating structural components present in FPL 55712. Montelukast originated from an early quinoline lead, which was modified with leukotriene structural elements. Zafirlukast is based on a lead compound that incorporated structural components from both FPL 55712 and the leukotrienes. Therefore, each medicinal chemistry strategy that was originally employed has successfully identified clinically effective leukotriene receptor antagonists.

Cysteine-specific radioiodination of proteins with fluorescein maleimide

A protocol is described for coupling of carrier-free iodine to protein sulfhydryl groups via fluorescein maleimide. 125I is first coupled to fluorescein maleimide in the presence of chloramine T. Iodination is stopped with sodium thiosulfate, and the iodine-substituted fluorescein maleimide is reacted with free cysteines of the protein. Excess label is then removed by gel-permeation chromatography. The procedure avoids exposition of the protein to oxidative conditions and does not require purification of the labeled carrier reagent. Suitability of the method for a given protein can be evaluated spectrophotometrically without employing radioactivity. It can be applied under denaturing conditions and may be particularly useful with mutant proteins carrying engineered single cysteine residues at sites that are not functionally critical.

Application of [(125)I]-[Tyr8]-substance P prepared by the chloramine-T method to receptor-binding experiments after subsequent reduction with mercaptoethanol and purification by reversed-phase liquid chromatography

Radiolabeling of [Tyr8]-substance P ([Tyr8]-SP) with the (125)I-isotope was performed by use of the chloramine-T technique. The primary formed radiolabeled product, having been quantitatively converted to the corresponding sulfoxide yielding [(125)I]-[Tyr8]-(Met11-->O)-SP completely lacked any binding to proteins rich in SP receptor populations. However, after reductive treatment with mercaptoethanol for about 2 h, a complete reconstitution of the Met11 thioether structure was observed. The reduced peptide, consisting of [(125)I]-[Tyr8]-(Met11)-SP was separated from its by-products by reversed-phase high-performance liquid chromatography on octadecylsilyl silica gel with 100 mM triethyl ammonium formate buffer containing 22% acetonitrile (pH 2.2). The labeled SP derivative prepared by this two-step synthesis was obtained in 73% overall yield related to the [Tyr8]-SP starting material and exhibited a specific activity of 1.9-10(6) Ci/M. In contrast to [(125)I]-[Tyr8]-->(Met11-->O)-SP, satisfactory receptor-binding was now observed with the [(125)I]-->[Tyr8]-(Met11)-SP derivative.

Determination of zafirlukast, a selective leukotriene antagonist, human plasma by normal-phase high-performance liquid chromatography with fluorescence detection

A high-performance liquid chromatographic (HPLC) method was developed for the determination of zafirlukast, a selective peptide leukotriene receptor antagonist, in human plasma. Zafirlukast and the internal standard, ICI 198 707, were extracted from deproteinated plasma samples using large reservoir C18 solid-phase extraction columns and analyzed by normal-phase liquid chromatography with fluorescence detection. The method had a lower limit of quantitation of 0.75 ng/ml and a linear calibration curve in the range of 0.75 to 200 ng/ml. The absolute recovery of zafirlukast was > 90%, and the within-day and between-day relative standard deviations were < 9%. The utility of the method in the characterization of the plasma concentration-time profiles of zafirlukast in clinical studies was demonstrated.

Characterization of iridovirus IV1 polypeptides: mapping by surface labelling

A comprehensive index of IV1(Tipula iridescent virus, or TIV)-associated polypeptides has been established using enrichments of "empty" and "filled" virions that are considered to be maturation-phase-related. The mapping strategy which involved one- and two-dimensional polyacrylamide gel electrophoresis, silver staining, disulphide bond reduction and 125I iodination of putative surface proteins revealed 103 and 116 polypeptides for empty and filled capsids, respectively. These estimates could be reduced to < or = 70 by reclassing multicharged polypeptides of approximately identical masses as single entitles. At least 10 polypeptides from empty and filled virions were involved in intermolecular sulphhydryl linkages and another 11 species were identified as putative outer shell (surface) polypeptides. These data provide useful criteria for iridovirus classification and identification of candidate polypeptides involved in capsid formation and maturation.

Nitric oxide mediates intracytoplasmic and intranuclear zinc release

We previously described that NO. leads to destruction of ZnS clusters and release of Zn2+ from various proteins including zinc finger transcription factors. To assess the relevance in living cells, we investigated, whether exogenous NO. leads to an increase of cytoplasmic and nuclear free Zn2+. L929 cells, mouse splenocytes, or rat aorta endothelial cells were labeled with Zinquin-E, a Zn2+-specific fluorophore, and were treated with two different spontaneous NO donors, S-nitrosocysteine or DETA/NO. Both NO donors strongly increased the Zn2+-dependent fluorescence in the cellular cytosol and also in nuclei as compared to controls. NO-dependent Zn2+ release in splenocytes was quantitated by flow cytometry. These results show for the first time, that nitrosative stress mediates intracellular and intranuclear Zn2+ release which may be relevant in altering gene expression patterns.

Development and validation of chiral high-performance liquid chromatographic methods for the quantitation of valsartan and of the tosylate of valinebenzyl ester

A stereospecific HPLC method for the quantitation of CGP 49309 in samples of its corresponding enantiomer valsartan has been developed and validated. The enantiomeric separation was achieved on a 5 micron silica-bonded, alpha 1-acid glycoprotein column (Chiral AGP) with a phosphate buffer, pH 7, containing 2% (v/v) 2-propanol as a mobile phase. The linearity was established in the range 0.1-4% (r > 0.999). The limit of quantitation was 0.1% and the limit of detection was 0.04%. The accuracy of the method was found to be 96.7% (average). For the precision (repeatability), a relative standard deviation value of 2.4% was found. Similarly, a stereoselective HPLC method was also developed and validated for the quantitation of the enantiomer of the starting material used for the synthesis of valsartan, namely (R)-valinebenzyl ester tosylate. Baseline resolution of the enantiomers of valinebenzyl ester tosylate could be achieved on the chiral crown ether column Crownpak CR (Daicel) at 50 degrees C using water-methanol-trifluoroacetic acid (850:150:1, v/v) as a mobile phase. The linearity was established in the range 0.5-5% (r > 0.999). The accuracy of the method was found to be 100.5% (average). For the precision (repeatability), a relative standard deviation value of 3.4% was found. Both methods were found to be suitable for the analysis of the respective analytes.

In vitro fibrinolysis after adding low doses of plasminogen activators and plasmin generation with and without oxidative inactivation of plasmin inhibitors in newborns and adults

PURPOSE

The aim of this study was to investigate in vitro fibrinolysis after adding low doses of plasminogen activators and to determine the functional role of plasmin inhibitors in newborns and adults.

PATIENTS AND METHODS

We have studied the kinetics of in vitro fibrinolysis after adding low doses of urokinase (UK) and recombinant tissue plasminogen activator (rt-PA) by use of a microtiter clot lysis assay. Additionally, we have determined plasmin generation with and without oxidative inactivation of plasmin inhibitors in newborns and adults.

RESULTS

The 50% lysis time in the clot lysis assay correlated with the activator dose and was significantly shorter in newborns at rt-PA concentrations of < 0.21 microgram/ml. When UK was used as an activator, the 50% lysis time was slightly but significantly prolonged in newborns at concentrations of 140-200 IU/ml, whereas we could find lower values (non-significant) at 110 and 80 IU/ml. Plasmin generation after oxidative inactivation of plasmin inhibitors was significantly lower in newborns, even when compared with adult plasma, which was diluted 50%. However, in a physiological plasma milieu (containing natural inhibitors), there were no differences in plasmin generation when streptokinase (SK) was used as an activator and only minor differences when UK was used.

CONCLUSIONS

Our data indicate a more rapid clot lysis at low UK and rt-PA concentrations in newborns despite significantly reduced plasminogen levels. The results of the plasmin generation experiments suggest a diminished effect of plasmin inhibitors towards fetal plasmin, which raises an explanation for the concentration-related differences in the clot lysis assay. The experience with thrombolytic agents in newborns is limited. Most dosage regimens for thrombolytic therapy in children or adults consist of an initial bolus infusion, followed by low-dose continuous treatment. Based on the results of our clot lysis experiments, we think that especially the continuous infusion of plasminogen activators after bolus administration should not be enhanced in newborns compared to older children or adults.

Development of magnetic beads for rapid and efficient metal-chelate affinity purifications

Metal-chelate affinity chromatography offers multiple advantages for protein purification, yet existing resins make its applications to sparse, hydrophobic, or particularly labile proteins and peptides quite difficult. In this work, we have developed a simple method to covalently modify commercially available superparamagnetic beads with a six-carbon spacer and nitrilotriacetic acid to provide a novel resin for extremely rapid and efficient metal chelate affinity purifications. Further, the small size and surface chemistry of these beads provide clear improvement in applicability to small scale purifications with reduced nonspecific adsorption. These advantages have been demonstrated relative to a commercially available nickel resin.

A simplified method for the analysis of hydroxyproline in biological tissues

A critical study of the different steps involved in previous procedure for hydroxyproline assay allows the direct measurement of collagen content in tissue' homogenates without losing the advantages of the method. The procedure is based on alkaline hydrolysis of the tissue homogenate and subsequent determination of the free hydroxyproline in hydrolyzates. Chloramine-T was used to oxidize the free hydroxyproline for the production of a pyrrole. The addition of Ehrlich's reagent resulted in the formation of a chromophore that can be measured at 550 nm. Optimal assay conditions were determined using tissue homogenate and purified acid soluble collagen along with standard hydroxyproline. Critical parameters such as the amount of chloramine-T, sodium hydroxide, p-dimethylaminobenzaldehyde, pH of the reaction buffer, and length of oxidation time were examined to obtain satisfactory results. The method has been applied to samples of tissue homogenate and purified acid soluble collagen, with recovery of added hydroxyproline of 101 +/- 6.5 and 104 +/- 6.0 (SD) percent, respectively. The method is highly sensitive and reproducible when used to measure the imino acid in tissue homogenates. The modified hydroxyproline assay presented in this communication will be useful for routine measurement of collagen content in extracts of various tissue specimens. In addition, the modified method can be used for batch processing of column fractions to monitor the collagen concentrations during purification.

GLP-1/GIP chimeric peptides define the structural requirements for specific ligand-receptor interaction of GLP-1

The gastrointestinal hormones glucagon-like peptide-1 (GLP-1) and gastric inhibitory polypeptide (GIP) strongly stimulate insulin release. Despite their high N-terminal sequence similarity, GLP-1 does not bind to the GIP receptor and vice versa. To characterize the domains required for interaction of the peptide ligands with their specific receptors, we performed displacement studies with various synthetic GLP-1/GIP hybrid peptides on RINm5F insulinoma cells. Displacement of 125I-GIP and 125I-GLP-1 was measured using GLP-1/GIP chimeras which comprised GIP and GLP-1 sequences at different positions. The binding affinity to the GLP-1 receptor was found to be sensitive to GIP-like exchanges in the N-terminal 22 amino acids as well as in positions 13 and 15 (loss of affinity 280-fold to more than 1000-fold). C-terminal substitution of the GLP-1 sequence by GIP diminished the affinity towards the GLP-1 receptor only 20-fold. All hybrid peptides investigated showed minimal binding affinity for the GIP receptor, indicating that the entire GIP-sequence (1-31) is important for receptor recognition. These findings provide insight into the structural requirements for the specific interaction of two important insulinotropic peptides with their specific receptors.

Labeling of insulin with non-radioactive 127I and application to incorporation of radioactive 125I for use in receptor-binding experiments by high-performance liquid chromatography

Conditions for the labeling of insulin with radioactive iodine isotopes were investigated by means of incorporation of non-radioactive 127I into the peptide. Either the chloramine-T (CT) or lactoperoxidase-hydrogen peroxide (LPO) technique was applied and reversed-phase high-performance liquid chromatography (RP-HPLC) was used for analysis of the reaction products. The LPO method provided the 127I-labeled peptide within 15-30 min, whereas the CT alternative yielded the labeled substrate even within 15 s. However, the latter reaction can only be controlled in a reproducible manner with difficulty and undesired side-reactions became increasingly prominent when the reaction time of 15 s was exceeded for only a few seconds. In another experiment, the LPO technique was applied for radiolabeling insulin with 125I. The product was first purified by size-exclusion chromatography (SEC) and then subjected to RP-HPLC. SEC yielded two peaks. The smaller one, which eluted at a slightly higher Kd value (accounting for about 14% of total radioactivity) predominantly consisted of material eluting at the column's void volume under the conditions of RP-HPLC, whereas the main SEC fraction (accounting for about 86% of total radioactivity) yielded a single peak, as shown by HPLC. The radioactive material attributable to the main SEC fraction revealed the expected receptor-binding properties, as evidenced by displacement experiments with non-radioactive insulin, as well as the action of tetradecanoyl phorbol acetate on the binding characteristics and thus indicating formation of a labeled hormone retaining biological activity.

3,4-di-O-acetyl-2,5-anhydro-1,6-di-O-(p-tolylsulfonyl)-D-mannitol

The title compound, 2,5-bis(4-methylphenylsulfonyloxy-methyl)oxolane-3,4-diyl diacetate, C24H28O11S2, lies on a crystallographic twofold axis. It adopts a perfect twist 3(4)T conformation in the solid state. The puckering parameters of the tetrahydrofuran ring are q = 0.32 (8) A and rho = 92.3 (5) degrees. The acetyl groups are planar, with the non-H atoms deviating less than 0.002 (3) A from their mean plane. They have an (S)-cis conformation with the C-O and C = O bonds eclipsed, and each acetyl group is orientated with the C = O group syndiaxial to the C-H bond at the ring C atom to which the group is attached.

Surface modifications of alginate/poly(L-lysine) microcapsular membranes with poly(ethylene glycol) and poly(vinyl alcohol)

Three different surface modifications were conducted on the membranes of double-layer alginate/poly(L-lysine) microcapsules with tosyl chloride-activated poly(ethylene glycol), cyanuric chloride-activated poly(ethylene glycol) and tosyl chloride-activated poly(vinyl alcohol), separately. All these surface modifications strengthen the microcapsular membranes. Of the three surface-modified microcapsules, those treated with cyanuric poly(ethylene glycol) and tosylated poly(vinyl alcohol) have mechanical strength higher than that treated with tosylated poly(ethylene glycol). The permeabilities of the proteins were only slightly affected by the surface modifications. When IW32 erythroleukaemia cells were entrapped inside these microcapsules, cells proliferated to a density of (1.0-1.5) x 10(7) cells cm-3 after 7 d culturing compared with 2 x 10(6) cells cm-3 attained by free cell culturing. The intracapsular concentration of erythropoietin which was secreted by the IW32 cells accumulated to concentrations of 5-7 U cm-3. In addition, 3T3 cells were found to have a very low tendency to attach to the microcapsular membranes of all three surface-modified preparations.

Effects of pteridines on luminol-dependent chemiluminescence induced by chloramine-T

Pteridines are ubiquitous in living organisms, but little is known about their biological functions. Different pteridines were tested for their ability to modulate luminol-dependent chemiluminescence induced by chloramine-T at pH = 7.5 and at a concentration of 100 microM for each pteridine. We observed striking differences between the compounds; whereas reduced pteridine species were generally potent scavengers, aromatic pteridines were weak to strong enhancers of the chemiluminescence. Taking into account the detailed chemical structure of the molecules, by multiple linear regression analysis a simple index was constructed that allows prediction of the effects of the different pteridines with high accuracy (linear correlation coefficient between predicted and observed values r = 0.89). The effects of different pteridines on free radical-induced chemiluminescence might bear biological significance since, for example, certain pteridines take part in enzymic reactions involving free-radical intermediates, or are related to the activation of macrophages in close relationship with the oxidative burst.

Degradation and disposal of some enzyme inhibitors. Scientific note

Five enzyme inhibitors (phenylmethylsulfonyl fluoride, 4-amidinophenylmethanesulfonyl fluoride, 4-(2-aminoethyl)benzenesulfonyl fluoride, N alpha-p-tosyl-L-lysine chloromethyl ketone, and N-tosyl-L-phenylalanine chloromethyl ketone) in buffer, DMSO, or stock solutions were completely degraded by adding 1M NaOH and the final reaction mixtures were not mutagenic. The stability of these compounds decreased as the pH increased.

(4aR,8R,SR)-8-(p-tolylsulfinyl)-2,3,4,4a,5,6,7,8-octahydro-4a-quinolinol

The title compound, C16H21NO2S, isolated from the reaction of lithiated racemic 2,3,4,4a,5,6,7,8-octahydroquinoline with 0.5 equivalents of (-)-(1R,2S,5R)-menthyl (SS)-p-toluenesulfinate, possesses the unusual conformation in which the OH and bulky p-toluenesulfinyl groups are in axial positions. The S=O bond distance of 1.519 (3) A is longer than expected because of intramolecular hydrogen bonding between the hydroxyl group and the sulfinyl O atom.

Synthesis of the 123I- and 125I-labeled cholinergic nerve marker (-)-5-iodobenzovesamicol

The highly toxic curraremimetic and cholinergic neuron marker (-)-5-iodobenzovesamicol (IBVM) has been labeled with iodine-125 and iodine-123. [125I]IBVM, suitable for animal distribution and ex vivo autoradiographic studies, was synthesized by solid-state exchange; isolated yields were 65-89% with specific activities in the range of 130-200 Ci/mmol. The synthesis of no-carrier-added (-)-5-[125I]IBVM from the corresponding chiral (-)-5-(tri-n-butyltin) derivative using Na125I was evaluated using the oxidants H2O2, peracetic acid and chloramine-T. Both peracetic acid and chloramine-T gave good yields (70-95%). However, when Na123I was utilized, acceptable yields of [123I]IBVM were obtained only with chloramine-T. Use of the latter oxidant did produce 5-chlorobenzovesamicol which was eliminated during HPLC purification. After optimization of the reaction parameters, [123I]IBVM in batch sizes of 10-27 mCi, is routinely obtained with a specific activity of 30-70,000 Ci/mmol, radiochemical purity (> 97%) and chiral purity (> 98%). Isolated radiochemical yields have averaged 71% (N = 40). Distribution analyses of [125I]IBVM and [123I]IBVM in mice 4 h following intravenous administration show essentially equivalent concentrations of the two tracers in the four brain regions sampled. The exceptionally high specific activity of [123I]IBVM has made possible the evaluation of this radiotracer in humans.

Chloramine-T in radiolabeling techniques. I. Kinetics and mechanism of the reaction between chloramine-T and amino acids

The determination of the rate and pH dependency of chlorination of amino acids by chloramine-T (CAT) using the model compounds beta-alanine, L-alanine, and L-alanine ethyl ester was investigated. The reactions were studied under pseudo-first-order conditions where the amino acid concentration was in large excess over CAT. The rates of the reactions were determined spectrophotometrically by following the disappearance of CAT. The overall reaction was found to obey second-order kinetics. The effect of pH was studied over the range 6.1 to 12.0. The reaction rate was found to be independent of pH in the range 6.1 to 8.5, and to decrease with increasing pH above 8.5. The pH dependency was rationalized by assuming that un-ionized CAT reacts with the un-ionized amino group of the amino acid. The value of the resulting second-order rate constant (1.9 x 10(7) M-1 min-1) was of the same order of magnitude as rate constants reported for similar N-chlorination reactions. A cyclic transition state involving a water molecule is proposed.

Crystal structure and conformation of two N-tosyl-protected dipeptides containing amino acids with polar side-chains

X-Ray diffraction studies and energy-minimization calculations were carried out on two dipeptides, N-tosyl-L-Ser-Gly-OMe monohydrate (C13H18N2O6S.H2O, compound A) and N-tosyl-L-Thr-Gly-OMe (C14H20N2O6, compound B). Compound A crystallized in the monoclinic system, space group P2(1) with unit cell parameters a = 4.915(1), b = 15.625(4), c = 11.003(1) A, beta = 91.28(1) degrees, V = 844.8 A3. M(r) = 348.4, d = 1.37(2) g cm-3, Z = 2, lambda(Cu K alpha) = 1.5418 A, mu = 1.99 mm-1, T = 293 K. R = 0.032 for 1451 unique reflections with I > 2 sigma(I). Compound B crystallized in the orthorhombic system, space group P2(1)2(1)2(1), with unit cell parameters a = 5.050(2), b = 16.483(3), c = 20.769(5) A, V = 1729.3 A3, Z = 4. M(r) = 344.4, d = 1.32(2) g cm-3, mu(Cu K alpha) = 1.90 mm-1. R = 0.040 for 1060 unique reflections with I > 2 sigma(I). The major difference in the backbone conformation of the two compounds is in their glycine residues, with the glycine residue in compound A adopting an extended conformation with phi = -132.6(3) degrees and psi = 175.3(3) degrees and that in compound B having a folded conformation with phi = -56.3(6) degrees and psi = -42.6(7) degrees. In compound A the oxygen atom of the Ser side-chain and the carbonyl oxygen atom of glycine are bridged by the water of crystallization through O--H ... O hydrogen bonds, resulting in the relatively rare trans conformation [chi = -175.7(2) degrees] for this side-chain.(ABSTRACT TRUNCATED AT 250 WORDS)

beta-Lactamase inhibitors derived from N-tosyloxy-beta-lactams

Electrophilic N-tosyloxy-beta-lactams, N-tosyloxy-4-phenyl-2-azetidinone (2b) and N-tosyloxy-3-(S)-phthalimido-4-(S)-2-azetidinone (2c), are described. These agents are novel potent beta-lactamase inhibitors.

Crystal structure of 2,5-anhydro-1-O-(p-tolylsulfonyl)-D-mannitol

2,5-Anhydro-1-O-(p-tolylsulfonyl)-D-mannitol, C13H18SO7, Mr = 318.4, monoclinic, C2, a = 26.370(6), b = 7.9741(11), c = 6.6801(6) A, beta = 91.401(11) degrees, V = 1404.3(6) A3, Z = 4, DX = 1.506 g/cm3, CuK alpha, lambda = 1.54184 A, mu = 23.03 cm-1, F(000) = 672, T = 296(1) K, R = 0.042 for 2832 observations with I > 3 sigma (I) (of 2864 unique data). On the esterified side of the molecule, three bond lengths and three bond angles show small changes compared to the unesterified side, which is similar to the symmetrical parent compound, 2,5-anhydro-D-mannitol. The conformation of the five-membered ring is E5 with P = 49.3 degrees and tau m = 38.1 degrees. The hydroxymethyl groups adopt g+ and g- dispositions similar to the parent molecule. The three hydroxyl groups are involved in a network of intermolecular hydrogen bounds both as donors and acceptors.

Effect of cysteinyl-leukotriene receptor antagonist ICI 204.219 on allergen-induced bronchoconstriction and airway hyperreactivity in atopic subjects

The effects of a highly selective leukotriene D4 receptor antagonist, ICI 204.219, on allergen-induced bronchoconstriction and changes in airway reactivity were evaluated in a double-blind, placebo-controlled, crossover trial. Ten atopic subjects were selected for the study on the basis of an immediate fall in forced expiratory volume in 1 s (FEV1) of at least 15% and a least a doubling dose fall in their PC20-histamine (the concentration of histamine needed to reduce FEV1 by 20%) after antigen challenge. Baseline PC20-histamine was determined before the ingestion of a single oral 40 mg dose of ICI 204.219 or matched placebo. 2 h later subjects were challenged with aerosolised allergen; FEV1 was measured for the next 6 h then PC20-histamine was remeasured. Two subjects did not complete the study for reasons not related to the trial medication. ICI 204.219 significantly attenuated the early and late phase bronchoconstriction to inhaled allergen (mean treatment difference in area under the FEV1-time curves 2529 [95% Cl 1085-3972] delta %FEV1.min; p less than 0.005: and 3537 [528-6545] delta %FEV1.min; p less than 0.03) and suppressed the allergen-induced increase in non-specific bronchial reactivity (mean treatment difference 1.03 [0.34-1.71] doubling dilutions of histamine; p less than 0.01). These findings suggest that ICI 204.219 may be a disease-modifying agent in asthma. Further studies are under way to evaluate its clinical efficacy.

Side reaction of pyrenylalanine-peptides containing NG-tosylarginine during detosylation with hydrogen fluoride

Formation of by-products of pyrenylalanine-peptides was observed during the cleavage of a tosyl group in pyrenylalanine-peptides containing an Arg(Tos) residue with HF. NMR and fluorescence experiments showed that by-products were compounds in which a pyrenyl group was modified with a tosyl group(s). The side reaction was little suppressed by the addition of usual scavengers such as anisole, 1,2-ethanedithiol, thioanisole and p-cresol. Under the conditions used for the cleavage of N alpha-Boc group, i.e., trifluoroacetic acid or 4 M HCl in dioxane, the pyrenylalanine residue was stable. No side reaction was, furthermore, observed in the reductive cleavage with sodium in liquid ammonia. These results suggest that the side reaction may be due to an electrophilic attack of tosyl cations to the electron-rich pyrenyl group in the pyrenylalanine residue under the HF-mediated acidic conditions.

Photodiode array spectral identification of modified amino acids in synthetic peptides following high resolution HPLC separation

The products of peptide synthesis are routinely purified by reversed-phase HPLC with single wavelength detection at 214 nm. Additional information regarding the peptide product and any contaminating sequences can be obtained by high resolution HPLC combined with high sensitivity spectral analysis using photodiode array detection. Full spectral characterization can be used to ascertain the presence of aromatic amino acid residues as well as side chain modifications such as blocking groups for protection of labile side chains. Many of the protecting groups used in solid phase synthesis contain distinctive structural features that can be identified by their spectra. Although the synthesis protocol provides for hydrolysis of these groups, it is possible that the product mixture may include some residual blocked material. Since the presence of blocking groups will affect the properties of the synthesized peptide, detection and complete removal are essential. Spectral analysis using photodiode array detection in conjunction with high resolution HPLC separations can be used to identify protected amino acid residues in synthetic peptides.