Variations in the activity of digestive enzymes along the intestine of the burbot Lota lota expressed by different methods

The activities of major digestive hydrolases (proteases, amylase, lipase and esterases) along the intestine were studied in the burbot Lota lota (L.) using different methods of activity expression. The enzyme activities were determined both in the whole gut segments and in the isolated mucosa, and then expressed in terms of tissue mass and protein content in the samples. Further, the cumulative activities of these enzymes in the pyloric caeca were compared with those in the rest of the intestine to estimate the overall contribution of these regions to digestion. The data obtained suggest the essential role of the pyloric caeca in the digestion of the burbot. In addition, the variations in the pH values along the intestine and the changes in the enzyme activities with incubation temperature were examined. The study proved the method of enzyme activity expression to be a key factor influencing the outcome of the experiment.

Trypsin from the pyloric ceca of pectoral rattail (Coryphaenoides pectoralis): purification and characterization

Trypsin from the pyloric ceca of pectoral rattail (Coryphaenoides pectoralis) was purified and characterized. Purification was carried out by ammonium sulfate precipitation, followed by column chromatographies on Sephacryl S-200, DEAE-cellulose and Sephadex G-50. The enzyme was purified 89-fold with a yield of 2.2%. Purified trypsin had an apparent molecular weight of 24 kDa when analyzed using SDS-PAGE and size exclusion chromatography. Optimal profiles of pH and temperature of the enzyme were 8.5 and 45 degrees C, respectively, using N(alpha)-p-tosyl-l-arginine methyl ester hydrochloride as a substrate. It was stable in a wide pH range of 6-11 but unstable at a temperature greater than 40 degrees C. Trypsin was stabilized by calcium ion. The activity of purified trypsin was effectively inhibited by soybean trypsin inhibitor and TLCK and was partially inhibited by EDTA. Activity continuously decreased with increasing NaCl concentration (0-30%). The kinetic trypsin constants K(m) and K(cat) were 0.15 mM and 210 s(-1), respectively, while the catalytic efficiency (K(cat)/K(m)) was 1400 s(-1) mM(-1). The N-terminal amino acid sequence of trypsin was determined to be 12 residues (IVGGYECQEHSQ), and the sequence showed high homology to other fish trypsins.

Trypsin from the pyloric caeca of bluefish (Pomatomus saltatrix)

Trypsin was purified from the pyloric caeca of bluefish (Pomatomus saltatrix) by ammonium sulfate precipitation, acetone precipitation and soybean trypsin inhibitor-Sepharose 4B affinity chromatography. Bluefish trypsin migrated as a single band using both sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and native-PAGE and had a molecular mass of 28 kDa. The optima pH and temperature for the hydrolysis of benzoyl-dl-arginine-p-nitroanilide (BAPNA) were 9.5 and 55 degrees C, respectively. The enzyme was stable over a broad pH range (7 to 12), but was unstable at acidic pH, and at temperatures greater than 40 degrees C. The enzyme was inhibited by specific trypsin inhibitors: soybean trypsin inhibitor (SBTI), N-p-tosyl-l-lysine chloromethyl ketone (TLCK) and the serine protease inhibitor phenylmethyl sulfonylfluoride (PMSF). CaCl2 partially protected trypsin against activity loss at 40 degrees C, but NaCl (0 to 30%) decreased the activity in a concentration dependent manner. The N-terminal amino acid sequence of trypsin was determined as IVGGYECKPKSAPVQVSLNL and was highly homologous to other known vertebrate trypsins.

Phenotypic flexibility of digestive system in Atlantic cod (Gadus morhua)

This study examined the restoration of the digestive capacity of Atlantic cod (Gadus morhua Linnaeus) following a long period of food deprivation. Fifty cod (48 cm, 1 kg) were food-deprived for 68 days and then fed in excess with capelin (Mallotus villosus Müller) on alternate days. Ten fish were sampled after 0, 2, 6, 14 and 28 days and the mass of the pyloric caeca, intestine and carcass determined. Two metabolic enzymes (cytochrome c oxidase and citrate synthase) were assayed in white muscle, pyloric caeca and intestine, and trypsin activity was measured in the pyloric caeca. A delay of 14 days was required before body mass started to increase markedly, whereas most of the increase in mass of both the pyloric caeca and intestine relative to fish length occurred earlier in the experiment. By day 14, the activities of trypsin and citrate synthase in the pyloric caeca as well as citrate synthase in the intestine had reached maxima. The growth of the digestive tissues and restoration of their metabolic capacities thus occur early upon refeeding and are likely required for recovery growth to take place. The phenotypic flexibility of the cod digestive system is therefore remarkable: increases in trypsin activity and size of pyloric caeca resulted in a combined 29-fold increase in digestive capacity of the fish during the refeeding period. Our study suggests that Atlantic cod are able to cope with marked fluctuations in food availability in their environment by making a rapid adjustment of their digestive capacity as soon as food availability increases.

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.

Carboxypeptidase E in rat antropyloric mucosa: distribution in progenitor and mature endocrine cell types

Processing of most gut hormones involves cleavage between dibasic amino acids followed by carboxypeptidase-catalyzed removal of the COOH-terminal basic residue, resulting in peptides with a COOH-terminal glycine. Such peptides may subsequently be converted to amidated peptides or can be directly secreted. It is believed that carboxypeptidase E (CPE) is involved in gut hormone processing but its presence in gut endocrine cells has never been studied. We have analyzed the distribution of CPE in the antropyloric mucosa of rat stomach and report that gastrin cells and progenitor gastrin-somatostatin (G/D) cells express CPE while mature somatostatin cells and the majority of serotonin cells fail to express CPE. These data indicate that immature G/D cells are able to process gastrin to glycine-extended forms and that CPE-mediated processing is not a characteristic of mature somatostatin and serotonin cells.

Distribution of heme oxygenase-2 in nerves and interstitial cells of Cajal in the normal pylorus and in infantile hypertrophic pyloric stenosis

CONTEXT

Interstitial cells of Cajal (ICCs) are pacemaker cells, which are of fundamental importance in regulating gastrointestinal motility. Recent evidence suggests that carbon monoxide is a neurotransmitter involved in neurotransmission between ICC and smooth muscle cells. Heme oxygenase-2 (HO-2) is the major physiological mechanism for the generation of carbon monoxide in the enteric nervous system.

OBJECTIVE

To investigate the immunocolocalization of HO-2 and ICCs in the normal pylorus and in infantile hypertrophic pyloric stenosis (IHPS).

DESIGN

Specimens from 18 infants with IHPS and 8 control specimens were examined using double-immunostaining with c-Kit and HO-2 antibodies. The immunolocalization was detected with the help of confocal laser scanning microscopy.

RESULTS

Abundant HO-2 immunoreactivity was found in ICCs in the smooth muscle layer of normal pylorus. There was a decrease in the number of ICCs and lack of HO-2 immunoreactivity in ICCs in IHPS.

CONCLUSIONS

The results of the present study provide the first evidence for the presence of HO-2 in ICCs in the normal human pylorus. The lack of ICCs and HO-2 in IHPS suggests impaired intracellular communication between ICCs and smooth muscle cells, contributing to motility dysfunction in IHPS.

Isolation and characteristics of trypsin from pyloric ceca of the starfish Asterina pectinifera

Trypsin was purified from pyloric ceca of the starfish Asterina Pectinifera by ammonium sulfate precipitation, gel filtration, and cation-exchange chromatography. Final enzyme preparation was nearly homogeneous in sodium dodecyl sulfate-polyacrylamide gel electrophoresis and its molecular weight was estimated as approximately 28000. Optimum pH and temperature of A. pectinifera trypsin for hydrolysis of N(alpha)-p-Tosyl-L-arginine methyl ester hydrochloride were approximately pH 8.0 and 55 degrees C, respectively. A. pectinifera trypsin was unstable at above 50 degrees C and below pH 5.0, and was not activated by adding Ca(2+). The N-terminal amino acid sequence of A. pectinifera trypsin, IVGGHEF, was found.

Site-specific gene expression of nNOS variants in distinct functional regions of rat gastrointestinal tract

5' mRNA variants of neuronal nitric oxide synthase (nNOS) are generated either by alternative promoter usage resulting in different mRNAs that encode for the same protein (nNOSalpha) or alternative splicing encoding NH(2)-terminally truncated proteins (nNOSbeta/gamma) that lack the PDZ/GLGF domain for protein-protein interaction of nNOSalpha. We studied the expression of 5' nNOS mRNA forms and nNOS-interacting proteins (postsynaptic density protein-95; PSD-95) in the rat gastrointestinal tract and analyzed the more distinct localization of nNOS protein variants in the duodenum by immunohistochemistry with COOH- and NH(2)-terminal nNOS antibodies. 5' nNOS mRNA variants showed a site-specific expression along the gastrointestinal tract with presence of all forms (nNOSalpha-a, -b, -c; nNOSbeta) in the muscle layer of esophagus, stomach, duodenum, longitudinal muscle layer of jejunum/ileum, proximal colon, and rectum. In contrast, a lack of nNOSalpha-a and nNOSbeta mRNA was observed in pylorus, circular muscle layer of jejunum/ileum, and cecum. Expression of nNOSalpha and nNOSbeta cDNAs revealed proteins of ~155 kDa and 135/125 kDa, respectively. Immunohistochemistry showed a differential distribution of COOH- and NH(2)-terminal nNOS immunoreactivity in distinct layers of rat duodenum, suggesting a cell-specific expression and distinct compartmentalization of nNOS proteins. Observed distribution of 5' nNOS mRNA variants and proteins argue for a complex control of nNOS expression by usage of separate promoters, cell- and site-specific splicing mechanisms, and translational initiation. These mechanisms could be involved in gastrointestinal motor diseases and may explain the phenotype of nNOSalpha knockout mice with gastric stasis and pyloric stenosis, due to a total loss of nNOS in the pyloric sphincter region.

Time-course changes in the expression of Na+, K+-ATPase in gills and pyloric caeca of brown trout (Salmo trutta) during acclimation to seawater

Changes in protein and mRNA expression of Na(+),K(+)-ATPase in gills and pyloric caeca of brown trout were investigated on a detailed time course after transfer from freshwater to 25 ppt seawater (SW). A transient deflection in plasma osmolality and muscle water content lasting from 4 h until day 3 was followed by restoration of hydromineral balance from day 5 onward. Gills and pyloric caeca responded to SW transfer by increasing Na(+),K(+)-ATPase activity from days 5 and 3, respectively, onward. In both tissues, this response was preceded by an increase in alpha-subunit Na(+), K(+)-ATPase mRNA as early as 12 h posttransfer. The similarity of the response in these two organs suggests that they both play significant physiological roles in restoring hydromineral balance after abrupt increase in salinity. Further, SW transfer induced a slight, though significant, increase in primary gill filament Na(+), K(+)-ATPase immunoreactive (NKIR) cell abundance. This was paralleled by a marked (50%) decrease in secondary lamellar NKIR cell abundance after less than 1 d in SW. Thus, SW acclimation in brown trout is characterised by a lasting decrease in overall NKIR cell abundance in the gill. We propose that SW transfer stimulates Na(+),K(+)-ATPase enzymatic activity within individual chloride cells long before (<1 d) it becomes apparent in measurements of whole-gill homogenate enzymatic activity. This is supported by the early stabilisation (12 h) of hydromineral balance.

Purification and characterization of pancreatic elastase from North Atlantic salmon (Salmo salar)

An elastase I-like enzyme was purified to homogeneity from the pyloric caeca of North Atlantic salmon (Salmo salar) and compared with porcine elastase I. The molecular weight and isoelectric point were estimated to be 27 kDa and over 9.3, respectively. The pH optimum was between 8.0 and 9.5, and the enzyme was unstable at pH values below 4. Kinetic properties examined using Suc-(Ala)3-p-nitroanilide showed that the catalytic efficiency of salmon elastase was about 2.5 times higher than that of porcine elastase. Furthermore, the salmon enzyme was less stable at lower pH values and temperatures than the porcine enzyme. The preference for amino acids at the primary binding site was found to be different from that of the porcine elastase. The salmon elastase binding pocket seems to prefer more branched aliphatic residues than the porcine elastase.

Nitric oxide synthase-containing nerve elements in the pylorus of the cat

Combined nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d) histochemistry, nitric oxide synthase (NOS) and vasoactive intestinal polypeptide (VIP) immunocytochemistry were used to study the distribution of NOS- and VIP-containing nerve elements in the feline pylorus. A large number of stained multipolar neurons was found in the myenteric plexus. However, some NADPH-d and NOS positive neurons were also observed in the submucous plexus and in the internal part of muscular layer. A few stained perikarya were found in the tunica mucosa, in a very close situation to the blood vessels. A large number of thin varicose fibres, with intense reaction for all markers were seen around or in close contact with the unstained perikarya to the blood vessels and some of them around the pyloric glands. The density of NOS and NADPH-d positive nerve elements was much higher than that of VIP-immunoreactive (IR) nerve elements. Our results suggest that nitric oxide (NO) might act as a regulatory neurotransmitter of the pyloric sphincter, blood flow and secretion in this region.

Purification and characterization of tissue kallikrein-like proteinases from the black sea bass (Centropristis striata) and the southern frog (Rana berlandieri)

Serine proteinases were isolated from the pyloric caeca of the black sea bass (Centropristis striata) and the pancreas of the Southern frog (Rana berlandieri) and were purified to apparent homogeneity by aprotinin affinity column chromatography, reverse phase high performance liquid chromatography and gel filtration FPLC liquid chromatography to produce products with molecular masses of approximately 27,000 Da and isoelectric points from 4.2 to 5.0. Both enzymes were kallikrein-like and were bound by diisopropylfluorophosphate; had pH optima from 9 to 10; showed high specificity for the hydrolysis of arginine peptide bonds and low to moderate affinity for lysine bonds at the P1 substrate recognition sites; were inhibited by aprotinin, benzamidine, leupeptin, and soybean trypsin inhibitor; generated kinin from kininogen and were highly stable at room temperature. Differences between the enzymes were observed relative to their hydrophobicities, substrate specificities, stabilities at acidic pHs in the presence and absence of calcium, and the amounts of kinin generated from kininogen. Many of the fish trypsins, previously identified as anionic trypsins, may actually be more kallikrein-like.

[The pepsinogen of the gastric mucosa in the red-cheeked suslik Citellus erythrogenys]

Studies have been made on the isozymic composition of pepsinogen (polyacrylamide gel electrophoresis) and peptidase activity in gastric mucosa of the ground squirrel at various stages of hibernation. Eight pepsinogen isoforms were found in acid-producing zone of the mucosa, pyloric mucosa lacks first three of them, its peptidase activity being two times lower than in other parts of the stomach. During hibernation, no significant changes were found in fractional composition of pepsinogen, peptidase activity being decreased twofold only in the fundulus of the stomach, remaining practically constant in other parts of the latter. This finding indicates that the stomach is ready for the activity irrespectively of food uptake.

[Effects of qualitatively different food on acidity and proteolytic activity in different parts of the stomach of patients with duodenal ulcer]

Using an original technique, the authors studied acid-proteolytic activity in the stomach at night in 44 patients with duodenal ulcer before and after 12-h fasting; after meat, starch gel, vegetable oil meals. It was found that long-term fasting does not result in changed acid-proteolytic activity in the stomach body, though reduces a mean acid concentration in the stomach antral-pyloric portion 2-fold. Proteins and carbohydrates do not influence the acidity and produce multidirectional action on proteolytic activity of the stomach content: proteins inhibit, but carbohydrates enhance proteolysis. Vegetable oil results in a moderate decrease of the acidity.

Nitric oxide synthase activity in infantile hypertrophic pyloric stenosis

BACKGROUND

Hypertrophic pyloric stenosis is a common infantile disorder characterized by enlarged pyloric musculature and gastric-outlet obstruction. Its physiopathologic mechanism is not known, but a defect in pyloric relaxation (pylorospasm) has been postulated. Nitric oxide is a mediator of relaxation in the mammalian digestive tract, raising the possibility that pylorospasm could be caused by a defect in nitric oxide production. Since neuronal nitric oxide synthase and NADPH diaphorase are identical, we used the NADPH diaphorase histochemical reaction to study the distribution of nitric oxide synthase in pyloric tissue from patients with infantile hypertrophic pyloric stenosis.

METHODS

We studied pyloric tissue from nine infants with infantile hypertrophic pyloric stenosis and seven control infants and children. Cryostat sections were processed for NADPH diaphorase histochemical analysis. A polyclonal tau antiserum was used to identify the enteric nervous system by immunohistochemical methods.

RESULTS

NADPH diaphorase activity was restricted to the enteric nervous system and blood vessels. In the pyloric tissues from the control patients, intense diaphorase activity was present in the nerve fibers of the circular musculature, in the neurons and nerve bundles of the myenteric plexus, and in some nerve fibers of the longitudinal musculature. In the pyloric tissues from patients with infantile hypertrophic pyloric stenosis, the enteric nerve fibers in the hypertrophied circular musculature were enlarged and distorted and did not contain diaphorase activity, whereas the activity in the myenteric plexus and the longitudinal musculature was preserved.

CONCLUSIONS

We suggest that a lack of nitric oxide synthase in pyloric tissue is responsible for pylorospasm in infantile hypertrophic pyloric stenosis.

Immunohistochemical demonstration of pyloric gland-type cells with low-pepsinogen isozyme 1 in preneoplastic and neoplastic tissues of rat stomachs treated with N-methyl-N'-nitro-N-nitrosoguanidine

The appearance of pyloric gland-type cells with a low pepsinogen isozyme 1 (Pg 1) content in the stomach mucosa of F344/Du rats during stomach carcinogenesis was examined by a combination of paradoxical concanavalin A (Con A) staining and immunohistochemical staining for Pg 1. Male F344 rats were given drinking water containing 100 micrograms N-methyl-N'-nitro-N-nitrosoguanidine [(MNNG) CAS: 70-25-7]/ml for 30 weeks and then normal tap water and were killed in week 10, 20, 30, 40, 50, or 70. Untreated rats were killed in week 30 or 70. Serial sections of pyloric mucosa were stained by paradoxical Con A staining and Pg 1 immunostaining. After MNNG treatment, tissues showing changes were classified into normal-looking pyloric mucosa with a low Pg 1 content, mucosa showing atrophic or hyperplastic changes, adenomatous hyperplasia, and adenocarcinoma. From the results of paradoxical Con A staining and Pg 1 immunostaining, the cells in lesions were classified into gastric types (surface mucous cell type and pyloric gland cell type) and intestinal types (intestinal-absorptive cell type and goblet cell type). In this experiment, the cells in lesions were mainly of the gastric cell types. All pyloric glands of control rats in weeks 30 and 70 contained class III mucins and had a high Pg 1 content demonstrated immunohistochemically. After MNNG treatment, class III mucin-positive pyloric glands with a low Pg 1 content in normal-looking pyloric mucosa were found from week 10; subsequently, their number increased with time. Changed mucosa was found from week 20, and the area of cells of the pyloric gland cell type with little or no Pg 1 in changed mucosa was about 30% of the area of cells of the pyloric gland cell type. Adenomatous hyperplasias were found from week 30; adenocarcinomas were found from week 50. Almost all cells of the pyloric gland cell type (greater than 95%) in areas of adenomatous hyperplasia and adenocarcinomas had little or no Pg 1 content. The present results suggested that the appearance of pyloric glands with a low Pg 1 content in normal-looking mucosa might be an immunohistochemically detectable preneoplastic change preceding morphologically detectable preneoplastic changes in stomach carcinogenesis.

Development profile of neuron-specific enolase in human gut and its implications in Hirschsprung's disease

The most widely held view on the pathogenesis of Hirschsprung's disease as an arrest of neuroblast migration in the gut was based on the hypothesis of a single craniocaudal gradient of development of enteric neurons. Recent experimental studies in animals, however, have revived a contradictory hypothesis of a dual gradient of neuronal development; such data are not available in humans. To test these hypotheses in humans, we studied the pylorus, ileum, and colon of 28 fetuses with gestational ages of 9-21 wk, using immunohistochemical localization of neuron-specific enolase, a specific neuronal marker indicative of differentiation. Development of the enteric nervous system was shown to be most advanced in the pylorus, less so in the colon, and least so in the ileum. The findings support the hypothesis of a dual gradient of neuronal development proceeding from both ends to the middle of the gut in midtrimester human fetuses and suggest that the pathogenesis of Hirschsprung's disease needs to be reconsidered.

Trypsin from Greenland cod, Gadus ogac. Isolation and comparative properties

Trypsin(ogen) was isolated from the pyloric ceca of Greenland cod. Greenland cod trypsin catalyzed hydrolysis of N alpha-benzoyl-DL-arginine p-nitroanilide, tosyl arginine methyl ester and protein and was inhibited by the serine protease inhibitor PMSF and other well-known trypsin inhibitors. Greenland cod trypsin was more stable at alkaline pH than at acid pH; and was inactivated by relatively low thermal treatment. Like other trypsins, the enzyme was rich in potential acidic amino acid residues but poor in basic amino acid residues and had a molecular weight of 23,500; but it had less potential disulfide pairs, less alpha-helix and a lower H phi ave than other trypsins previously characterized. Reactions catalyzed by Greenland cod trypsin were not very responsive to temperature change, such that specific activity was relatively high at low reaction temperature.

Carbonic anhydrase in the monkey stomach and intestine

The distribution of carbonic anhydrase in the stomach and intestine of the cynomolgus monkey (Macaca fascicularis) was studied by the histochemical method of Hansson. In the gastric surface epithelium high enzyme activity was found in the cytoplasm and at the lateral cell borders. The parietal cells in the gastric glands also showed high enzyme activity, while the chief cells were less active. The mucous cells in the pyloric glands and in the Brunner's glands demonstrated a staining pattern similar to that of gastric surface cells. The mucosa of the duodenum and the jejunum was less intensely stained than the gastric mucosa. The enzyme activity was located at the lateral cell borders of the enterocytes, with weak or no cytoplasmic activity. Goblet cells and Paneth cells were unstained. In the ileum a small number of epithelial cells displayed high enzyme activity; their identity is not clear at present. In the cecum and colon large amounts of cytoplasmic carbonic anhydrase were found in the surface epithelium and in the upper part of the glands. Capillaries showing clear enzyme staining were found in the mucosa of all tissues; they were often located close to the surface epithelium and the glands. In the stomach, cecum and colon the distribution of the enzyme in the monkey appears very similar to that reported for other mammalian species, but in the small intestine clear differences exist. The functional role of carbonic anhydrase at the various sites in the gastrointestinal tract is only partly understood.

Studies on proteinases from the digestive organs of sardine. I. Purification and characterization of three alkaline proteinases from the pyloric caeca

Three alkaline proteinases designated I, II and III are found in the pyloric caeca of sardine and isolated by (NH4)2SO4 fractionation, DEAE-cellulose chromatography and gel filtration on Sephadex G-100. The final preparations were judged homogeneous by multiple criteria. The molecular weights of the enzymes I, II and III were determined by the sedimentation equilibrium method to be 22 900, 28 700 and 27 000, respectively. The isoelectric points were 5.45, 5.30 and 4.85, and the sedimentation coefficients (S0 20, w) were 2.91, 3.06 and 2.94, respectively. Enzymes II and III had similar amino acid compositions which were different from that of enzyme I, especially in the content of lysine, valine and tyrosine. All the enzymes belonged to a group of serine proteases. Enzymes II and III were found to be an anionic alpha-chymotrypsin-like enzymme and an anionic trypsin-like enzyme, respectively. Although these fish enzymes had properties in common with those of bovine pancreatic cationic trypsin and chymotrypsin, they are distinctly different in their optimum pH, pH stability, net charge and immunological properties.

Diamine oxidase activity in gastric and duodenal mucosa of man and other mammals with special reference to the pyloric junction

In the gastric mucosa of human subjects and of various mammals methylation was accepted as the main pathway of histamine catabolism. However, augmentation of gastric acid secretion by aminoguanidine, the strong inhibitor of diamine oxidase, indicated an influence of diamine oxidase activity on this secretory process. Therefore a careful reinvestigation of the occurrence of diamine oxidase activity was started from the distal duodenum in the direction of the cardia. In all species studied, diamine oxidase activity decreased from distal duodenum towards the pylorus. In dogs, landrace pigs and in human subjects the diamine oxidase activity clearly exceeded the pyloric borderline gradually becoming zero in corpus or fundus. In rabbits, however, and especially in mini-pigs no diamine oxidase activity was found beyond the pylorus. Among individuals gastric diamine oxidase activity showed a variable prevalence and could not be found regularly in all the subjects. In one patient with prepyloric ulcer a strong influence of pathophysiological processes on gastric diamine oxidase activity could be suspected. Thus, in every alteration of the gastric mucosa under experimental or clinical conditions also an alteration of gastric diamine oxidase activity should be taken into account.

Relationship between site of peptic ulceration and gastric acid-peptic activity: new evaluation of gastric analysis in patients with acute gastric bleeding and chronic peptic ulcer

In an attempt to elucidate the etiology of acute gastric bleeding and/or erosion and chronic peptic ulcer, a measurement of gastric juice and mucosal pepsin was carried out in surgically-treated patients. Patients with massive gastric mucosal bleeding in the fundic gland area showed high levels of fundic mucosal pepsin without acid-pepsin appearance in the gastric contents. In these patients, a significantly high value of the peptic activity ratio of gastric mucosa to gastric juice (MJPR, 36.4 +/- 6.7) was observed. It can be suggested that transient blockage of pepsin output from peptic cells with occur in the course of the acute mucosal bleeding, while acid-peptic digestion could be carried out within the fundic gland mucosa. On the other hand, a close correlation between relatively high acid-and-pepsin concentration of the gastric contents and a low level of MJPR (5.6 +/- 1.2) was observed in patients with chronic gastric ulcer. Patients who had a gastric ulcer within the pyloric gland mucosa had a highest acid-peptic activity among three groups with ulcers in fundic gland area, border zone and pyloric gland area. There is a rule that acid-peptic activity becomes low when the site of gastric ulcer moves from pylorus to fundus. A marked increase in acid-and-pepsin secretion into the gastric cavity was observed in patients suffering from chronic duodenal ulcer showing the lowest level of MJPR (3.40 +/- 0.50).

[Effect of insulin and insulin deficiency on the activity of hexokinase, malate dehydrogenase, lactate dehydrogenase and its isoenzyme composition in the smooth muscle of the rabbit stomach]

Decrease in the activity of hexokinase was found in soluble fraction of stomach smooth muscles of rabbits with alloxane diabetes. Administration of insulin into intact rabbits led to distinct decrease in the activity of lactate and malate dehydrogenases in cells of the stomach fundal part. In smooth muscles of rabbits with alloxane diabetes pyruvate was formed from lactate at a higher rate (increase in content of LDH1 and LDH2) and after administration of insulin into the animals--lactate was formed from pyruvate at an increased rate.

Changes in the antral mucosal pepsin in dogs with chronic ulcer: pathogenesis of cinchophen ulcer

All of the dogs given continuous injection of 100 mg/kg sodium cinchophen for 21 days developed chronic ulcers in the pyloric portion of the stomach. Those dogs given cinchophen exhibited a definite increase in gastric pepsin secretion. Readings of gastric mucosal pepsinogen showed a significant high concentration both in the fundic and pyloric gland area in the cinchophen-treated animals. As the injections were continued, the gastric mucosa-juice peptic activity ratio (MJPR) in the fundic gland area become low. These results do not point to pathological changes in the fundic gland area. The mean pH value of the surface of antral mucosa varied greatly from dog to dog and was slightly higher than normal. In the dog which had chronic ulcers in the antral portion, the antral mucosal pepsinogen concentration become eight times higher than that seen in the control animals. The incidence and chronicity of the cinchophen gastric ulcers were related to the local pepsin increase adjacent to the lesions. The origin of pepsin which appeared in the antral mucosa and cinchophen ulcerogenesis were discussed.

gamma-glutamyl transpeptidase of rat intestine: localization and possible role in amino acid transport

gamma-Glutamyl transpeptidase (gamma-GT), an enzyme possibly involved in amino acid transport, was investigated in rat small intestine using the synthetic substrate L-gamma-glutamyl-p-nitroanilide. Enzyme localization and characteristics were correlated with features of amino acid uptake. gamma-GT activity copurified with sucrase and alkaline phosphatase. Activity was maximal at pH 8.2 and was stimulated by monovalent cations. The relative specificity of the gamma-GT reaction with diglycine and eight essential amino acids as substrates correlated well with the rate of intestinal absorption of this dipeptide and these amino acids as observed by others. gamma-GT activity was 12-fold greater in the jejunum than in the ileum, again in agreement with relative rates of amino acid absorption along the length of rat intestine. The specific activity of gamma-GT in villus tip cells was 10 times greater than in crypt cells, and amino acid uptake was 2 to 6 times greater with villus tip than with crypt cells. Bromosulfophthalein, a noncompetitive inhibitor of gamma-GT, inhibited amino acid uptake. These studies support the concept that membrane gamma-GT may be involved in amino acid and dipeptide uptake, and indicate that further investigation of such involvement may be conveniently pursued using mammalian small bowel.

Partial purification and properties of phospholipase A2 from the starfish, Asterina pectinifera

1. Phospholipase A2 (phosphatide 2-acyl-hydrolase, EC 3.1.1.4) activity was shown to occur in the supernatant fraction of a freshly prepared homogenate from the pyloric caecum of starfish (Asterina pectinifera). 2. The phospholipase A2 has been isolated and purified 130-fold by ultracentrifugation, ammonium sulfate precipitation and column chromatographic procedures. 3. The purified enzyme was stable to heat at low pH values and the optimal pH was observed at approximately 9.0. 4. The enzyme activity was activated by Ca2+ and sodium deoxycholate, and was inhibited by EDTA.