Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.4.21.4 (trypsin)
42,187 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

It has been demonstrated by the methods of histochemical and biochemical examination of the activity of the enzymes that the mucus layer covering the small intestinal wall contains active enzymes (alkaline phosphatase, leucin aminopeptidase IV, saccharase, lactase) and pancreatic enzymes (alpha-amylase and trypsin). Emphasis is laid on the enrichment of the mucus layer with pancreatic enzymes as compared with small intestinal juice. A hypothesis has been advanced according to which the mucus layer undergoes degradation of polymeric and oligomeric substrates, which plays a physiological part in the digestion of nutritive substances and protection of the internal medium against immunoactive biopolymers. The digestion occurring in the mucus layer is proposed to be called mucus digestion.
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PMID:[Enzymes in the mucosal layer of the small intestine]. 619 54

Growth hormone (GH)-releasing activity has been detected in extracts of carcinoid and pancreatic islet tumors from three patients with GH-secreting pituitary tumors and acromegaly. Bioactivity was demonstrated in 2 N acetic acid extracts of the tumors using dispersed rat adenohypophyseal cells in primary monolayer culture and a rat anterior pituitary perifusion system. The GH-releasing effect was dose responsive and the greatest activity was present in the pancreatic islet tumor. Small amounts of activity were also found in two other tumors (carcinoid and small cell carcinoma of lung) unassociated with GH hypersecretion. Each of the tumors contained somatostatin-like immunoreactivity but the levels did not correlate with the net biologic expression of the tumor. Sephadex G-75 gel filtration indicated the GH-releasing activity to have an apparent molecular size of slightly greater than 6,000 daltons. The GH-releasing activity was adsorbed onto DEAE-cellulose at neutral pH and low ionic strength, from which it could be eluted by increasing ionic strength. The GH-releasing activity was further purified by high pressure liquid chromatography using an acetonitrile gradient on a cyanopropyl column to yield a preparation that was active at 40 ng protein/ml. Partially purified GH-releasing activity, from which most of the bioactive somatostatin had been removed, increased GH release by pituitary monolayer cultures to five times base line. Enzymatic hydrolysis studies revealed that the GH-releasing activity was resistant to carboxypeptidase, leucine-aminopeptidase, and pyroglutamate-amino-peptidase but was destroyed by trypsin and chymotrypsin, indicating that internal lysine and/or arginine and aromatic amino acid residues are required for biologic activity and that the NH2-terminus and CO9H-terminus are either blocked or not essential. The results provide an explanation for the presence of GH-secreting tumors in some patients with the multiple endocrine neoplasia syndrome, type I, and warrant the addition of GH-releasing activity to the growing list of hormones secreted by tumors of amine precursor uptake and decarboxylation cell types.
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PMID:Partial purification and characterization of a peptide with growth hormone-releasing activity from extrapituitary tumors in patients with acromegaly. 624 40

The fragmentation of corticotrophin-(1--24)-tetracosapeptide in vivo has been studied, using tritium-labelled hormone and chromatography, in the rat. After intravenous injection the levels of peptide in the circulation declined rapidly caused by its distribution to the tissues and from 2 min after injection a range of different cleavage products appeared. Many of the fragments in the circulation after 2 min have been identified and in this way cleavage has been shown to occur after residues 1, 2, 8, 15, 16, 17, 19, 20 and 21. It is believed that this is the result of aminopeptidase attack at the NH2 terminal, and of attack on the basic region of the molecule by trypsin-like endopeptidase followed by carboxypeptidase. The sulphoxide has been identified as a major metabolite in some experiments but the extent of its formation was very variable. Seventy per cent of the dose was distributed to the tissue beds by 1 min. Part of this was present, mainly as intact peptide, in liver and kidney but the greater proportion was found in muscle, skin and intestine where extensive degradation had already occurred. Further characterization of the fragments formed in the muscle provided good evidence that this tissue may have been the site of generation of many of the fragments which later appeared in the circulation.
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PMID:Mechanisms of catabolism of corticotrophin-(1--24)-tetracosapeptide in the rat in vivo. 624 13

When deplasticized Epon sections were treated with endo- and/or exopeptidases prior to incubation with antibodies, the neuropeptide immuno-reactivity of secretory nerves was often altered in a predictable way. Cleavage of neurosecretory material in octopus nerves by trypsin and carboxypeptidase-B enhanced enkephalin-like immunoreactivity, while Molluscan neuropeptide-like immunoreactivity was prevented by tryptic cleavage. The enzyme effects indicated the occurrence of a heptapeptide (Tyr-Gly-Gly-Phe-Met/Leu-Arg-Phe) that contains both the enkephalin and the Molluscan neuropeptide sequence. Vasopressin terminals of the rat neurohypophysis, which presumably contain enkephalin precursor sequences, exhibited enkephalin-like immunostaining after tryptic cleavage. ACTH/beta-endorphin cells of the rat intermediate pituitary, which synthesize the enkephalin sequence at the N-terminus of Beta-endorphin, exhibited enkephalin=like immunoreactivity when sections were treated with alpha-chymotrypsin or trypsin, but not after incubation with leucine-aminopeptidase or carboxypeptidase-B. Enkephalin-like immunostaining could not be induced in any way in ACTH/beta-endorphin cells of the anterior pituitary. Enzymatic cleavage may give additional information in immunocytochemical localization studies on neuropeptide sequences in secretory nerves and hormonal granules.
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PMID:Enzymatic cleavage prior to antibody incubation as a method for neuropeptide immunocytochemistry. 628 42

The rate of degradation of cholecystokinin octapeptide, related fragments and analogs by human and rat plasma was investigated, using high pressure liquid chromatography for the separation and identification of the degradation products. CCK tetrapeptide showed a half-life of 13 min in human plasma while its cleavage in rat plasma occurred at a very high rate (half-life of less than 1 min). The kinetics of disappearance of both sulphated and unsulphated CCK-8 indicated more than a single rate of degradation; the faster degrading system showed a half-life of 18 min for unsulphated CCK-8 and of 50 min for the sulphated peptide in human plasma as compared respectively with 5 and 17 min in rat plasma. The cleavage of CCK-8 was inhibited by bestatin and puromycin, suggesting that aminopeptidases play a major role in the breakdown of this peptide. CCK-9 analogs were rapidly converted into their corresponding octapeptides (half-life of 2.7 min in human plasma). This conversion was inhibited by puromycin and bestatin, suggesting the participation of aminopeptidase(s) probably specific for basic amino acids. CCK decapeptide exhibited a greater stability than the nonapeptides (half-life of 30 and 45 min in human and rat plasma respectively) and also gave rise to CCK-8 as degradation product. This cleavage was not affected by aminopeptidase inhibitors but was decreased by aprotinin (Trasylol), suggesting that trypsin-like and/or kallikrein-like enzyme(s) were involved in the plasma metabolism of this peptide.
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PMID:Degradation of cholecystokinin octapeptide, related fragments and analogs by human and rat plasma in vitro. 629 Oct 99

The N-terminal extension peptide of type III procollagen, isolated from foetal-calf skin, contains 130 amino acid residues. To determine its amino acid sequence, the peptide was reduced and carboxymethylated or aminoethylated and fragmented with trypsin, Staphylococcus aureus V8 proteinase and bacterial collagenase. Pyroglutamate aminopeptidase was used to deblock the N-terminal collagenase fragment to enable amino acid sequencing. The type III collagen extension peptide is homologous to that of the alpha 1 chain of type I procollagen with respect to a three-domain structure. The N-terminal 79 amino acids, which contain ten of the 12 cysteine residues, form a compact globular domain. The next 39 amino acids are in a collagenase triplet sequence (Gly- Xaa - Yaa )n with a high hydroxyproline content. Finally, another short non-collagenous domain of 12 amino acids ends at the cleavage site for procollagen aminopeptidase, which cleaves a proline-glutamine bond. In contrast with type I procollagen, the type III procollagen extension peptides contain interchain disulphide bridges located at the C-terminus of the triple-helical domain.
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PMID:Complete amino acid sequence of the N-terminal extension of calf skin type III procollagen. 633 92

The presence of human blood group A determinants has been shown on the A+ rabbit intestinal brush border glycoproteins, particularly hydrolases. Sugar compositions of aminopeptidases N from A+ and A- rabbits were compatible with the presence in these molecules of eight N-linked glycans and of two O-linked glycans bearing the A determinants in A+ animals. The exact relative molecular masses of hydrophobic domain(s) of aminopeptidases N and A from pig and rabbit intestinal brush border have been determined by an isotopic dilution technique. The values obtained were compatible with the anchorage in the membrane of the monomeric rabbit enzymes, or of each subunit of the dimeric pig enzymes, by their N-terminal sequences, composed of 20-25 hydrophobic amino acids. This N-terminal hydrophobic sequence (14 residues) has been determined for rabbit aminopeptidase N. Short peptides containing approximately 60% hydrophobic amino acids have been extracted by chloroform-methanol from purified brush border and basolateral membranes of pig enterocytes. Their molecular properties were very similar to those of the aminopeptidase anchors released by trypsin treatment of detergent-extracted enzymes. However, several lines of evidence failed to support the assumption that these free hydrophobic peptides can be identified with anchors left inside the bilayer after proteolytic cleavage of surface hydrolases.
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PMID:Aminopeptidases and proteolipids of intestinal brush border. 634 98

The proteolytic enzymes contained in the preparation from Streptomyces 771 have been separated by isoelectric focusing in the sucrose density gradient at pH 3-10. The following enzymes have been identified: three multiple forms of neutral metal proteinase (pI 5.1, 6.37, 7.8) each of which splits DNP-Gly-Gly decreases-Val-ArgOMe; elastase-like metal proteinase active with respect to RBB-elestin with pI 10.68; metal-dependent peptidases: leucin aminopeptidase active with respect to L-RBB-elastin with pI 10.68 metal-dependent peptidases: leucin aminopeptidase active with respect to L-leucin n-nitroanilide and L-leucin beta-naphtylamide with pI 7.65, 7.15, 6.67, 6.45, 5.7, 5.35, 5.22, 4.83; carboxy peptidase with pI 5.95, 6.37; serine metal-dependent subtilisin-like proteinase active with respect to 2-Ala-Ala-LeupNA, 2-Gly-Gly-LeupNA, 2-Ala-LeupNA; two multiple forms of serine trypsin-like proteinase active with respect to BAEE and BApNA with pI 4.35, 4.76; serine chymotrypsin-like proteinase with pI 8.68 active with respect to ATEE.
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PMID:[Isoelectric focusing of a preparation of proteolytic enzymes from Streptomyces 771]. 634 61

Two peptidases which convert 125I-Lys-Arg-ME and 125I-ME-Arg6, respectively, to 125I-ME, have been identified and characterized in bovine adrenomedullary chromaffin granules. The former is referred to as a secretory granule peptidase (SGP) and the latter as a carboxypeptidase B-like enzyme (CPB-like) [7] which is here further characterized. SGP cleaved 125I-Lys-Arg-ME to produce only 125I-ME and was localized in chromaffin granules which contained Co2+-stimulated CPB-like activity, ME, and catecholamines. Both the SGP and the CPB-like enzymes appear to be thiol-metalloproteases. While the CPB-like enzyme seems likely to be involved in processing the enkephalin precursors [7], SGP may function as a trypsin-like or aminopeptidase enzyme in secretory granules.
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PMID:Two peptidases that convert 125I-Lys-Arg-(Met)enkephalin and 125I-(Met)enkephalin-Arg6, respectively, to 125I-(Met)enkephalin in bovine adrenal medullary chromaffin granules. 637 57

Aminopeptidase activity was demonstrated in the spermatozoa of the sea urchin, Strongylocentrotus intermedius. The enzyme solubilized from sperm cells was inactivated with bestatin, amastatin, p-chloromercuribenzenesulfonate, ZnCl2, and trypsin, whereas that in the intact cells was scarcely affected by these agents. On the other hand, bestatin ethyl ester inactivated the two enzyme forms to almost the same extent. It also inhibited the fertilization process in this species. These results suggest that the aminopeptidase associated with the spermatozoa is shielded with a permeable barrier and plays some role in fertilization.
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PMID:Sea urchin sperm aminopeptidase: comparative studies of sperm-associated and -solubilized enzymes. 667 49


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