Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.21.1 (chymotrypsin)
 10,938 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Sulfhydryl oxidase (SOX) is present in human milk and in milk from all species that have been studied. The pH optimum of human milk SOX is in the neutral range between 7.0 and 7.5. Human milk SOX is stable in an acid environment: 50% of its activity remains after 1 h at pH 2.5. Acid stability is also characteristic of gamma-glutamyltranspeptidase, another membrane-bound enzyme in skim milk. SOX is resistant to pepsin (4000 U/ml), trypsin (50 micrograms/ml), chymotrypsin (200 micrograms/ml), and to trypsin plus chymotrypsin (25 micrograms each/ml). Milk SOX activity has been detected in the stomach and proximal small intestine contents of suckling rats. Human and bovine SOX are relatively heat stable: 75% of the latter remains after treatment at 62.5 degrees C for 30 min and 65% of the former remains after treatment at 60 degrees C for 10 min. Neither remains after 62.5 degrees C for 30 min.
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PMID:Sulfhydryl oxidase in human milk: stability of milk enzymes in the gastrointestinal tract. 614 24

Rat pancreases were minced and treated with collagenase or collagenase supplemented with chymotrypsin to yield a mixture of ducts, islets, acinar cell clusters, blood vessels, and nerves. Histologically and ultrastructurally, the isolated tissues resembled their in situ counterparts in most respects, the major difference being the destruction of the basement membranes (basal laminae). Ducts ranging in size from the common bile/main pancreatic duct to the intercalated ducts were identified in the digest, although interlobular ducts were most frequently observed. Acinar tissue fragments were separated from nonacinar structures either by flotation through discontinuous gradients of Ficoll or by sieving, the latter technique being the more efficient. Common bile/main ducts, interlobular ducts, and blood vessels were selected manually from the nonacinar fractions. Biochemical analyses showed that the entire nonacinar fraction, as well as isolated ducts and blood vessels, contained larger alkaline phosphatase, carbonic anhydrase, and Mg-ATPase specific activities than acinar tissue, whereas acinar tissue contained larger gamma-glutamyltranspeptidase and amylase activities. However, greater than 63% of the total recovered activity of each enzyme was associated with the acinar tissue. Both the association of the majority of each of these enzyme activities with the acinar tissue and the similarity in specific activities associated with ducts and blood vessels indicate that none of the enzymes tested is a unique marker for interlobular and larger ducts of the pancreas of the rat.
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PMID:Characterization of ducts isolated from the pancreas of the rat. 615 56

Aminopeptidase (AP) A, B, and M, gamma-glutamyltranspeptidase (GGT), endopeptidase I and II, membrane-associated endopeptidase I and II, dipeptidylaminopeptidase (DAP) I, II, and IV, trypsin and chymotrypsin were investigated with 4-methoxy-2-naphthylamine (MNA) substrates and ester proteinases with n-acetyl-L-methionine-1-naphthylester as substrate in the digestive tract of laboratory rodents. Biochemically, proteinases and ester proteinases show different activities in the salivary glands, esophagus, stomach, liver, pancreas, duodenum jejunum, ileum, and colon; sex differences in proteinase and ester proteinase activity were measured, especially in the submandibular gland of rats and mice. Histochemically these enzymes are preferentially localized in surface membranes, lysosomes, secretion granules, and Golgi apparatus of cells of the endocrine and exocrine secretory system, resorptive system and immune system of the digestive tract. Besides the general occurrence of lysosomal (DAP I and II, single cell types and functional units of these systems possess their own individual proteinase and ester proteinase equipment. The cells of the granulated tubules of rat and mouse submandibular gland contain endopeptidase I and ester proteinases, its acinar cells DAP IV, the chief cells of the stomach APA, enteroendocrine cells APA, APM, and DAP II, hepatocytes DAP IV or GGT and DAP IV, lymphocytes GGT and DAP IV, and enterocytes trypsin, chymotrypsin, and membrane-associated endopeptidase I and II. Sex differences in proteinase activity are most conspicuous in the granulated tubule cells of the rat and mouse submandibular gland. The data suggest that proteinases and ester proteinases are involved in specific functions of the cells of the digestive tract. Furthermore, myoepithelial cells, smooth muscle cells of the muscular layer of the stomach and intestine, connective tissue cells (including mast cells) and fibers, nerve cells of the myenteric plexus and the capillary bed of the digestive organs are equipped with some of these proteinases and with ester proteinases and show organ differences.
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PMID:Investigation of proteinases in the digestive tract using 4-methoxy-2-naphthylamine (MNA) substrates. 701 83

Acyl-transfer catalysed by gamma-glutamyltranspeptidase from bovine kidney was studied using gamma-L- and gamma-D-Glu-p-nitroanilide as the donor and GlyGly as the acceptor. The transfer of the gamma-Glu group to GlyGly was shown to be accompanied by transfer of the gamma-Glu group to water (hydrolysis). The results were compared with acyl-transfer catalysed by the representative serine protease, alpha-chymotrypsin. The main difference between the kinetic mechanism of the acyl-transfer reactions catalysed by these enzymes, which contain an active-site serine and form an acyl-enzyme intermediate but belong to different enzyme classes, was found to consist in the role of the enzyme-donor-acceptor complex. This complex is not formed at any acceptor concentrations in the acyl-transfer reactions catalysed by the serine proteases. In contrast, in the gamma-glutamyltranspeptidase-catalysed acyl-transfer the pathway going through the ternary enzyme-donor-acceptor complex formed from the enzyme-acceptor complex becomes the main pathway of the transfer reaction even at moderate acceptor concentrations. As a result, gamma-glutamyltranspeptidase catalysis follows a sequential mechanism with random equilibrium addition of the substrates and ordered release of the products. The second distinction concerns the inhibitory effect of the acceptor. In the case of alpha-chymotrypsin this was the result of true inhibition, i.e. a dead-end formation of the enzyme-acceptor complex. A salt effect caused by the acceptor was the rationale of a similar effect observed in acyl-transfer catalysed by gamma-glutamyltranspeptidase.
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PMID:gamma-Glutamyltranspeptidase-catalysed acyl-transfer to the added acceptor does not proceed via the ping-pong mechanism. 781 93

The present study was designed to assess the effects of centrifugation velocity, standing time after dilution, freezing-thawing and chymotrypsin on the determination of gamma-glutamyltranspeptidase (gamma-GT) activities in seminal plasma, and to establish an instruction for the standardisation and quality control for the determination of gamma-GT within the same laboratory and among different laboratories. The gamma-GT level and sperm concentration of each of 72 samples of seminal plasma obtained by centrifugation at 1000 g for 10 min or 3000 g for 15 min were assayed. In addition, gamma-GT activities in diluted seminal plasma with different standing time and in samples with or without chymotrypsin were measured. The results showed that there was a significant difference of gamma-GT levels in seminal plasma obtained by centrifugation at different velocities (P < 0.001), and that gamma-GT activities in seminal plasma measured after standing for 30 min after dilution were notably lower than those measured immediately after dilution (P < 0.001). However, the data indicated that both chymotrypsin and freezing-thawing had no apparent effect on the determination of seminal gamma-GT. In conclusion, standing time after dilution and centrifugation velocity should be standardised, and frozen seminal plasma could serve as quality control products for the determination of gamma-GT activity among different laboratories.
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PMID:Preliminary investigations on the standardisation and quality control for the determination of gamma-glutamyltranspeptidase activity in seminal plasma. 1721 2