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)

1. The inactivation of phosphoenolpyruvate carboxykinase (GTP) (EC 4.1.1.32) in liver extracts was catalysed by the microsomal fraction, and led to the enzyme becoming bound to the microsomal membranes. 2. Inactivation by microsomal fraction, typsin or heating at 48degreesC was accelerated by L-cystine, D-cystine and oxidized glutathione and decreased by dithiothreitol. 3. MnC1(2) and CoC1(2) protected the enzyme from inactivation by heat or microsomal fraction, but did not affect the inactivation caused by trypsin. 4. Several proteinase inhibitors had no effect on the microsomal inactivation reaction, suggesting that proteolysis was not involved. 5. It is argued that the initial step in the degradation of phosphoenolpyruvate carboxykinase (GTP) is an inactivation reaction, perhaps involving oxidized thiol compounds.
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PMID:Inactivation of phosphoenolypyruvate carboxykinase (GTP) by liver extracts. 94 93

The isolation and characterization of a microsomal arylaminopeptidase from rat kidney is reported. By treatment of a microsomal arylaminopeptidase-phosphatase-complex with trypsin and subsequent gel filtration of the solubilized proteins on Sepharose 6B a electrophoretic homogeneous arylaminopeptidase was obtained (yield, 3%; enrichment, 900 times). The following properties of the purified enzyme were determined: 1. Molecular weight: 182000 (gel filtration on Sepharose 6B) to 192000 (SDS-polyacrylamide gel electrophoresis). 2. Subunit structure: In the presence of 6 M guanidine - HC1 + 1% BETA-mercaptoethanol the enzyme dissociates into subunits (MW 46700, ESTIMATED BY SDS gel electrophoresis method). 3. Isoelectric point: 4,71 (agarose gel electrophoresis method). 4. UV characteristics: E 280nm/E260NM=1.3. 5. Substrate specifity: optimal substrates L-alanyl derivatives (anilide, beta-naphthyl amide, p-nitroanilide, 4-(phenylazo)-phenylamide and hydrazide). Among these compounds the anilide derivative was hydrolyzed most rapidly. Furthermore, di- and tripeptides, especially L-methionyl-L-leucine, were also split. No hydrolysis was observed with hemoglobin (pH 4.5 and 7.5) and amino acid- or peptide-ester substrates. 6. Optimal pH: 7.5 +/- 0,1; optimal temperature: 45 to 50 degrees C. 7. The enzyme has no transamidation activity with L-alanyl amide both as aminoacyl donator and -acceptor. 8. Influence of effectors: Heavy metal ions (Ni2+, Cd2+, Cu2+, Zn2+), chelating agents (EDTA, o-phenanthroline) and puromycin inhibit the enzyme significantly. SH-group reagents are without any influence. 9. L-alanyl-L-alanyl-4 (phenylazo)-phenylamide, a dipeptide aryl aminopeptidase substrate, is hydrolyzed by the purified enzyme preparation according to a consecutive or step by step mechanism.
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PMID:[Isolation and characterization of a microsomal arylaminopeptidase from rat kidney]. 97 46

Of the three primary sub-cellular fractions derived from mouse brain homogenates, the P3 (microsomal) fraction binds 3H-di-hydromorphine stereo-specifically with the highest capacity per mg. of protein; this level is nearly as great as that bound by purified synaptosomal plasma membranes (SPM). The binding to P3 is unlikely to be attributable to contamination with SPM, because a) ten times as much total binding is recovered in P3 as in SPM, and b) the level of binding to P3 is highest in a sub-fraction banding above 0.8 M sucrose, rich in surface membranes of all types, whereas SPM bands preferentially at at 0.8 M sucrose, rich in surface membranes of all types, whereas SPM bands preferentially at 0.8-1.1 M sucrose. The binding of either 3H-di-hydromorphine or 3H-naloxone to P3 is, however, indistinguishable from that found in nerve endings with respect to a) its KD; b) the relative potencies of several agonists in displacing it; and c) the effects on it of Na+ or trypsin. Thus, it appears that stereo-specific opiate receptors are distributed diffusely on the entire surface of nerve cells and not concentrated at the synaptic region as has previously been supposed.
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PMID:The sub-cellular localization of stereo-specific opiate binding in mouse brain. 98 82

Rat liver microsomes incubated with [3H] puromycin in high salt buffer were digested with a mixture of protease, trypsin and chymotrypsin, in both the presence and absence of 1 % deoxycholate. Our observations revealed that the proteolysis of peptidyl puromycin labeled with [3H] puromycin was at least partially protected by the presence of microsomal membrane. Immuno-chemical analyses have further shown that most of the nascent NADPH-cytochrome c reductase in the microsomes was digested with the proteases while serum albumin was effectively protected from the digestion. It is thus proposed that NADPH-cytochrome c reductase synthesized on the membrane bound ribosomes is not transported to the vesicular cavity but directly to the outer surface of the microsomal membrane in a form which is accessible to the proteases.
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PMID:Localization of nascent NADPH-cytochrome c reductase in rat liver microsomes. 111 86

Incubation of microsomes or sonicated dispersions of microsomal lipid containing (14-C)phosphatidylserine with rat liver mitochondria results in the transfer of radioactivity to the mitochondria. Transfer is time and temperature dependent and is stimulated by a factor in the 105 000 x g supernatant from liver homogenates. The supernatant factor is soluble at pH 5.1, stable to dialysis, and is inactivated by heating and by digestion with trypsin. Radioactivity accumulates in the mitochondria largley as phosphatidylethanolamine owing the activity of phosphatidylserine decarboxylase. Transfer to mitochondria, heat treated to inactivate the decarbosylase, is also promoted by the suppernatant factor, in which case the lipid appears to be incorporated into the mitochondrial membrane as unchanged phosphatidylserine.
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PMID:Transfer of phosphatidylserine from liposomes or microsomes to mitochondria. Stimulation by a cell supernatant factor. 112 3

Iodinated derivatives of glucagon containing an average of 1 to 5 g-atoms of 127I per mol have been prepared by reacting the hormone with increasing amounts of iodine monochloride. Their iodoamino acid composition has been determined by ion-exchange chromatography and electrophoresis, following hydrolysis by pronase. Iodination of the two tyrosyl residues occurs first and is nearly complete after addition of a 4-fold molar excess of ICl. Iodination of the single histidyl residue is a later event and does not exceed an average of one atom per residue. Hydrolysis of iodoglucagon by trypsin and subsequent separation of the iodotyrosyl peptides shows that iodine is equally distributed between tyrosyl residues 10 and 13. Crude iodoglucagon containing an average of 1 g-atom of iodine per mol has been resolved into several components of differing iodine content and iodoamino acid composition by chromatography on DEAE-cellulose. Monoiodoglucagon isolated by this procedure shows a single band when analyzed by polyacrylamide gel electrophoresis. Iodoglucagons containing an average of 1 to 4 g-atoms of iodine per mol are more potent than native glucagon in their ability to stimulate adenylate cyclase activity and to bind to glucagon receptors of liver cell membranes of the rat. The maximal increase in biological potency occurring upon iodination is about 5-fold with respect to adenylate cyclase activity, and 2-fold with respect to binding to receptors; tetra and triiodinated derivatives show, respectively, the highest potency. Similar effects occur whether inactivation by liver membranes is inhibited or not, indicating an enhancement in the intrinsic affinity of iodoglucagon for the receptors. Iodination beyong 4 g-atoms per mol slightly decreases the affinity of the hormone for adenylate cyclase and for the receptors. Iodination causes a 2-20 fold decrease in the ability of liver plasma membranes and of blood plasma to inactivate glucagon in vitro; these effects correlate with the degree of iodination. With liver microsomal membranes, a decrease in glucagon inactivation occurs only at iodine contents exceeding 4 g-atoms per mol, and lower degrees of iodination result in opposite effects. Monoiodination causes a 4-6-fold increase in the plasma concentration of glucagon within the first 18 min following a single intrvenous injection of the hormone to rats. More extensive iodination results, in addition, in a marked decrease in the rate of dissappearance of glucagon from the blood. The immunological reactivity of glucagon is little affected by monoidination, but strongly depressed by higher degrees of iodination...
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PMID:Iodoglucagon. Preparation and characterization. 114 Feb 1

Rats were fed for four weeks with different lipid diets to determine the effects on the endoplasmic reticulum membranes of the liver and on the postmitochondrial supernatant fraction of the gastroduodenal mucosa. The diets contained cholesterol, cacao butter, olive oil, and these in combination. The results showed that dietary lipids were able to modify the composition of the hepatic endoplasmic reticulum and, to a lesser extent, that of postmitochondrial fraction of gastroduodenal mucosa. Cacao butter in the diet decreased the relative proportion of protein in hepatic microsomes. Cholesterol and olive oil were able to increase the cholesterol content of microsomes. The trypsin digestion of membranes revealed that cholesterol increased the solubility of microsomal protein and decreased the trypsin sensitive protein-lipid binding. The neutral fat diets increased the binding of proteins to the membrane, and cholesterol had no effect when it was given in combination. The low power photomicrographs revealed vacuolization of the cytoplasm of the hepatocytes when rats were fed on lipid rich diets. Also fatty degeneration was present. Cholesterol in combination with olive oil, however, did normalize the structure of the hepatocytes to a marked extent.
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PMID:Dietary fats and properties of endoplasmic reticulum: I. Dietary lipid induced changes in composition of microsomal membranes in liver and gastroduodenal mucosa of rat. 116 May 21

The membrane protein cytochrome b5 and the polar and hydrophobic fragments into which it is cleaved by trypsin have been investigated, with major emphasis on the deoxycholate-solubilized form of the protein. Molecular weight measurements show that both the intact protein and the fragments are in a monomeric state in deoxycholate and that a small peptide of perhaps 15 residues is excised when the fragments are formed. Measurements of Stokes radius show that the major fragments are globular, but that intact cytochrome b5 has an asymmetric shape, consistent with a structure composed of two globular domains joined by a link region that may be as long as 30 to 40 A. Circular dichroism measurements were made in the far-ultraviolet and in the Soret region, and they add to previously existing data to make it virtually certain that the polar heme-containing domain is unaffected by proteolysis or by removal of deoxycholate. A significant change in the ultraviolet circular dichroism is, however, observed when proteolysis occurs and it is likely that it arises from the link between the domains, which appears to be highly structured (perhaps helical) in the intact protein, but randomly coiled after it is excised. The binding studies reported previously from this laboratory suggest that these inferences about the structure of cytochrome b5 in deoxycholate solution apply also to the protein as solubilized by detergent micelles, by phospholipid vesicles, or by the microsomal membrane.
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PMID:The two-domain structure of cytochrome b5 in deoxycholate solution. 116 68

The action of TSH on protein turnover in various subcellular fractions has been investigated in dog thyroid slices incubated in vitro. The results suggest a general inhibition by TSH of protein catabolism. Using double labeline (3/ and 14C) of the proteins, an increase of the disappearance of some labeled material from the microsomal fraction in the presence of TSH has been observed. The protein nature of this material has been established by testing its susceptibility to hydrolysis by trypsin. The fact that the microsomal pellet had to be treated by triton X 100 before hydrolysis by trypsin could occur, suggests that the material is probably enclosed in, or protected by membrane vesicles. Its high molecular weight and its ability to be immunoprecipitated by an antithyroglobulin serum suggest that the microsomal protein, the disappearance of which is stimulated by TSH, is thyroglobulin or one of its subunits. It is suggested that our results reflect the acceleration by TSH of the vectorial transfer of thyroglobulin through the membranes of the endoplasmic reticulum to the colloid space.
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PMID:Control by TSH of protein turnover in thyroid subcellular fractions. 126 64

Liver microsomal subfractions and Golgi membranes free from adsorbed and secretory proteins have a characteristic sugar composition. The ratio of mannose to galactose is largest in rough microsomes, smaller in smooth I microsomes, still smaller in smooth II microsomes, and smallest in Golgi membranes. There is about twice as much glucosamine in Golgi membranes and 3 times as much in smooth II microsomes as in the other microsomal subfractions. Golgi membranes are rich in sialic acid in comparison to rough microsomes and it is present at even higher levels in the two smooth microsomal subfractions. Increasing concentrations of deoxycholate preferentially remove protein-bound mannose and glucosamine, while releasing significantly less galactose. About half of the microsomal mannose and galactose can be liberated from the surface of intact microsomal vesicles by treatment with trypsin. When trypsin is added to permeable vesicles where the inside surface can be also attacked, an additional 20% of the total mannose but no additional galactose is liberated.
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PMID:Distribution of protein-bound sugar residues in microsomal subfractions and Golgi membranes. 127 91


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