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:3.4.24.3 (collagenase)
18,340 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Islets were isolated by mild collagenase digestion and microdissection from rat fetuses 2 days before term and pups 1 or 2 days after birth and their insulin and glucagon secretion studied in vitro. Fetal B cells were stimulated by 16.7 mmol/l glucose, 20 mmol/l leucine or 20 mmol/l arginine. Fetal A cells were not affected by glucose or leucine, but were significantly stimulated by arginine. Somatostatin abolished the effect or arginine on both IRI and IRG output. Neonatal islets proportionally released more insulin and glucagon than their fetal counterparts, but reacted to the tested agents in a similar fashion. During the perinatal period, pancreatic insulin storage increased at a higher rate than that of glucagon. It is concluded that fetal B cells are equipped with sensors to a variety of agents and able to modulate their secretory rate according to the concentration of these agents. A cells are reactive to arginine 2 days before term but do not become glucose reactive until several days after birth.
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PMID:Insulin and glucagon secretion by islets isolated from fetal and neonatal rats. 36 57

Dispersed cell preparations enriched in beta-cells were obtained by collagenase digestion of fetal bovine pancreas and separation by Ficoll gradient centrifugation. These cells actively incorporated [3H]leucine into proinsulin and insulin. Incubation of these cells in the presence of the arginine analogue, L-canavanine, resulted in the inhibition of conversion of newly formed proinsulin to insulin and the appearance of a radioactive component of molecular weight 11,000-12,000. Incorporation of [35S]methionine into this component was detected in the presence of canavanine, an event not observed in control incubation. Canavanine thus induced the formation of a component possessing molecular weight and compositional properties expected for preproinsulin. Further characterization of cellular products by polyacrylamide slab gel electrophoresis in sodium dodecyl sulfate showed a highly labeled band corresponding to molecular weight 18,000-20,000 which might be involved in insulin biosynthesis.
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PMID:Preparation of beta-cells from fetal bovine pancreas: characterization of insulin biosynthetic activity. 38 31

The non-collagenous N-terminal segment of type I procollagen from dermatosparactic sheep skin was isolated in the form of the peptide Col 1 from a collagenase digest of the protein. The peptide has a blocked N-terminus, which was identified as pyrrolid-2-one-5-carboxylic acid. Appropriate overlapping fragments were prepared from reduced and alkylated peptide Col 1 by cleavage with trypsin at lysine, arginine and S-aminoethyl-cysteine residues and by cleavage with staphylococcal proteinase at glutamate residues. Amino acid sequence analysis of these fragments by Edman degradation and mass spectrometry established the whole sequence of peptide Col 1 except for a peptide junction (7--8) and a single Asx residue (44), and demonstrated that peptide Col 1 consists of 98 amino acid residues. The N-terminal portion of peptide Col 1 (86 residues) shows an irregular distribution of glycine, whereas the C-terminal portion (12 residues) possesses the triplet structure Gly-Xy and is apparently derived from the precursor-specific collagenous domain of procollagen. The central region of the peptide contains ten cysteine residues located between positions 18 and 73 and shows alternating polar and hydrophobic sequence elements. The regions adjacent to the cysteine-rich portion have a hydrophilic nature and are abundant in glutamic acid. The data are consistent with previous physicochemical and immunological evidence that distinct regions at the N- and C-termini of the non-collagenous domain possess a less rigid conformation than does the central portion of the molecule.
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PMID:Amino acid sequence of the N-terminal non-collagenous segment of dermatosparactic sheep procollagen type I. 47 72

This work was undertaken to study the effect of prednisolone on glucagon release in mouse pancreatic islets isolated by the collagenase technique. Pretreatment of the donors with prednisolone (0.2--0.3 mg daily) induced an increase in glucagon release both in the absence (1005+/-75, SEM, vs. 796+/-46 pg/10 islets/60 min, p=0.019) and in the presence of 7.5 mM arginine (1500+/-119 vs. 1236+/-61 pg/10 islets/60 min, p=0.05). The glucagon content of the islets was not modified by the treatment (28.6+/-1.1 vs. 28.0+/-1.1 ng/50 islets). The addition of prednisolone (5 - 10(-5) M) into the medium, failed to affect significantly glucagon secretion. In agreement with previous human studies, our data indicate that chronic glucocorticoid administration augments the secretory activity of the A-cell. This does not seem to be a result of increased glucagon synthesis nor a direct effect of glucocorticoids on the glucagon-releasing mechanism. Rather, environmental changes induced by these hormones could be responsible for A-cell hyperfunction.
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PMID:Enhanced glucagon secretion by pancreatic islets from prednisolone-treated mice. 78 66

Perfusion of growth hormone inhibitory factor (somatostatin) into rat pancreas inhibited secretion of glucagon and insulin into medium containing 5.5 mM glucose. A 15-min infusion of arginine (20 mM) greatly increased glucagon and insulin secretion. When perfused simultaneously with arginine, somatostatin (55 nM) abolished the increase in glucagon secretion. The acute phase of insulin secretion in response to arginine was attenuated by somatostatin, and subsequent secretion was decreased to control levels. Pretreatment for 5 min with somatostatin blocked even acute-phase insulin secretion in response to arginine. Somatostatin did not affect basal or glucose-stimulated secretion of insulin from rat pancreatic islets isolated by the collagenase technique. Arginine-stimulated secretion of insulin was enhanced by somatostatin in isolated islets. These results demonstrate a direct effect of somatostatin on the pancreas to inhibit secretion of glucagon and insulin. The failure of somatostatin to inhibit insulin secretion in pancreatic islets may be due to alterations in the beta cells produced by the isolation procedure. It is also possible that the effect of somatostatin on insulin secretion may be mediated indirectly.
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PMID:Inhibition of glucagon and insulin secretion by somatostatin in the rat pancreas perfused in situ. 108 35

Pancreatic islets of mice were isolated by the collagenase method. After a preincubation period of 20 min they were incubated in Krebs-Ringer-albumin buffer in the presence of glucose. Concanavalin A (2 mg/ml) inhibits the glucose-induced release of insulin; this same property is shown by Concanavalin A bound to nonphagocytosable beads of Sephrose at lower concentrations (0.4 mg/ml). In pancreatic islets stimulated by tolbutamide, glibenclamide or arginine the secretion of insulin is not inhibited in the presence of Concanavalin A. The incorporation of tritiated leucine is not influenced by Concanavalin A. Since desialized pancreatic islets react in the same way the glucose-induced secretion of insulin appears to be a membrane-dependent process.
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PMID:Interactions of concanavalin A with isolated pancreatic islets. 110 13

A strategy is described for the rapid optimization of kcat/Km for protease substrates. Selected positions of a given peptide substrate sequence are varied through synthesis with mixtures of amino acids. Incubation of the resulting peptide mixture with the enzyme of interest and analysis by high pressure liquid chromatography provides a direct measure of analogs with enhanced kcat/Km. High performance liquid chromatography/continuous flow fast atom bombardment mass spectrometry is used to assign structure to each peak in the chromatogram. As an example of the utility and efficiency of "substrate mapping" we describe optimization of the collagenase substrate Dnp-Pro-Leu-Gly-Leu-Trp-Ala-D-Arg-NH2 (where Dnp is dinitrophenyl) at the P'1 and P'2 positions. Six different mixtures were prepared for evaluation, representing the synthesis of 128 different synthetic substrates. "Substrate mapping" has led to Dnp-Pro-Leu-Gly-Cys(Me)-His-Ala-D-Arg-NH2, a substrate that possesses a 10-fold better kcat/Km than Dnp-Pro-Leu-Gly-Leu-Trp-Ala-D-Arg-NH2.
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PMID:Rapid optimization of enzyme substrates using defined substrate mixtures. 130 83

Rat kidneys extract citrulline derived from the intestinal metabolism of glutamine and convert it stoichiometrically into arginine. This pathway constitutes the major endogenous source of arginine. We investigated the localization of enzymes of arginine synthesis, argininosuccinate synthase and lyase, and of breakdown, arginase and ornithine aminotransferase, in five regions of rat kidney, in cortical tubule fractions and in subcellular fractions of cortex. Argininosuccinate synthase and lyase were found almost exclusively in cortex. Arginase and ornithine aminotransferase were found in inner cortex and outer medulla. Since cortical tissue primarily consists of proximal convoluted and straight tubules, distal tubules and glomeruli, we prepared cortical tubule fragments by collagenase digestion of cortices and fractionated them on a Percoll gradient. Argininosuccinate synthase and lyase were found to be markedly enriched in proximal convoluted tubules, whereas less than 10% of arginase and ornithine aminotransferase, were recovered in this fraction. Arginine production from citrulline was also enriched in proximal convoluted tubules. Subcellular fractionation of kidney cortex revealed that argininosuccinate synthase and lyase are cytosolic. We therefore conclude that arginine synthesis occurs in the cytoplasm of the cells of the proximal convoluted tubule.
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PMID:Cellular and subcellular localization of enzymes of arginine metabolism in rat kidney. 131 26

In order to examine the potential role of bacterial collagenases in periodontal tissue destruction, we recently isolated a gene, prtC, from Porphyromonas gingivalis ATCC 53977, which expressed collagenase activity (N. Takahashi, T. Kato, and H. K. Kuramitsu, FEMS Microbiol. Lett. 84:135-138, 1991). The nucleotide sequence of the gene has been determined, and the deduced amino acid sequence corresponds to a basic protein of 37.8 kDa. In addition, Southern blot analysis indicated that the prtC gene is conserved among the three major serotypes of P. gingivalis. The enzyme has been purified to near homogeneity from Escherichia coli clone NTS1 following Mono Q anion exchange and sequential gel filtration chromatography. The molecular mass of the purified enzyme was estimated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis to be ca. 35 kDa, and the active enzyme behaved as a dimer following gel filtration chromatography. The collagenase degraded soluble and reconstituted fibrillar type I collagen, heat-denatured type I collagen, and azocoll but not gelatin or the synthetic collagenase substrate 4-phenylazobenzyloxycarbonyl-Pro-Leu-Gly-Pro-D-Arg. Enzyme activity was enhanced by Ca2+ and inhibited by EDTA, sulfhydryl-blocking agents, and the salivary peptide histatin. Preliminary evidence for the existence of a second collagenase expressed by strain 53977 was also obtained.
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PMID:Sequence analysis and characterization of the Porphyromonas gingivalis prtC gene, which expresses a novel collagenase activity. 131 40

Porcine ovary was found to contain enzyme activities hydrolyzing peptide 4-methylcoumaryl-7-amide (MCA) substrates with a preference for Arg-MCA bond. The activities were shown to be present almost exclusively in the follicular fluid and to increase several times during follicular maturation. The enzyme responsible for these activities is thought to be a serine proteinase as judged from its strong inhibition by diisopropylfluorophosphate (DFP), leupeptin and antipain. The molecular weight of the native enzyme was electrophoretically estimated to be approximately 350,000, the result indicating that the enzyme is clearly distinct from plasmin (M(r) = 80,000) and collagenase (M(r) = 30,000-65,000), both of which are thought to be involved in ovulatory process. The substrate specificity of the partially purified enzyme was qualitatively different from that of plasmin. These results suggest that the enzyme is a novel type of serine proteinase.
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PMID:Occurrence of a novel 350-kDa serine proteinase in the fluid of porcine ovarian follicles and its increase during their maturation. 136 31


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