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

Comparisons have been made between the active center geometries of lactate dehydrogenase and glyceraldehyde-3-phosphate dehydrogenase, chymotrypsin and papain, and glyceraldehyde-3-phosphate dehydrogenase and papain. In the dehydrogenases, orientation of the nicotinamide ring about the glycosidic bond is determined by the substrate stereochemistry. The proper positioning of the carboxyamide moiety allows for the close approach of the C4 atom on the nicotinamide and the reactive carbon of the substrate. It follows that, once the conformation of the substrate or substrate intermediate has been established with respect to the functional groups in the enzyme, the A- or B-side specificity of the nicotinamide ring is predetermined. Hence, dehydrogenases which are divergently evolving from a common precursor must maintain the nicotinamide specificity if the protein fold of the catalytic domain is conserved. The tetrahedral intermediates produced during acylation of chymotrypsin and papain are found to be of opposite hand, while those of papain and glyceraldehyde-3-phosphate dehydrogenase can be regarded to be of the same hand. Thus the serine proteases, subtilisin and those of the chymotrypsin family, are of one hand while the cysteine enzymes, glyceraldehyde-3-phosphate dehydrogenase and papain, are of the other.
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PMID:Convergence of active center geometries. 14 59

1. The effects of secretin and pancreozymin-C-octapeptide and phosphodiesterase inhibitors on the concentration of adenosine 3',5'-cyclic monophosphate (cyclic AMP) and on the release of enzymes from rat pancreas have been studied. 2. In determininging cyclic AMP by means of the saturation assay of Brown et al. ((1971) Biochem. J. 121, 561-563) it is found essential to purify the pancreatic tissue extract by ion-exchange chromatography prior to the assay. 3. Injection of synthetic secretin or pancreozymin-C-octapeptide in anaesthetized rats in a secretory active dose (0.1 nmol) has no effect on the pancreatic cyclic AMP level. 4. Incubation for up to 10 min of pancreatic slices in Krebs-Ringer bicarbonate glucose medium containing 10(-2) M theophylline as phosphodiesterase inhibitor does not result in an increase of the cyclic AMP level. With 10(-2) M 1-methyl-3-isobutylxanthine as phosphodiesterase inhibitor the level is more than doubled after the first min of incubation and remains constant thereafter. 5. Addition of 3-10(-7) M secretin to slices incubated in the presence of 10(-2) M theophylline causes 84% increase of the cyclic AMP level above control, whereas the addition of 3-10(-7) M pancreozymin-C-octapeptide has no significant effect. In the presence of 10(-2) M 1-methyl-3-isobutylxanthine the latter hormone causes significant increases of up to 34% above control during 10 min of incubation. Secretin in this condition augments the cyclic AMP level by up to 296% above control during a 10 min incubation period. Addition of secretin and pancreozymin-C-octapeptide together has no greater effect than of secretin alone. 6. A broken cell fraction of rat pancreas contains adenylate cyclase activity which can be stimulated to 457 and 600% above the basal activity by 3-10(-7) M pancreozymin-C-octapeptide and secretin, respectively. Incubation of pancreatic slices with either hormone has no effect on the cyclic AMP phosphodiesterase activity in the homogenate of these slices. 7. Pancreozymin-C-octapeptide, dibutyryl cyclic AMP, 1-methyl-3-isobutylxanthine and carbamylcholine cause an elevated release of chymotrypsin from pancreatic slices incubated for 2 h in Krebs-Ringer bicarbonate medium, containing 10 mM glucose, while secretin, cyclic AMP and butyric acid have no significant effect. The release of the cytoplasmic enzyme lactate dehydrogenase is also elevated by dibutyryl cyclic AMP, 1-methyl-3-isobutylxanthine and carbamylcholine, but not significantly by pancreozymin-C-octapeptide. 8. The results support the role of cyclic AMP in the action of secretin, and do not exclude a mediating function of this nucleotide in the actions of pancreozymin in rat pancreas.
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PMID:Rat pancreatic adenylate cyclase. IV. Effect of hormones and other agents on cyclic AMP level and enzyme release. 18 33

Pyrolysis gas chromatography (PGC) has been shown to be useful for differentiating enzymes. The enzymes alpha-chymotrypsin, lactate dehydrogenase, catalase, and urease were easily "fingerprinted" on a 1.8 m 0.5% Carbowax 20 M column. Also, in some cases, isoenzymes of lactate dehydrogenase could be distinguished. Based on the pyrolyses of the free aromatic amino acids, four major enzyme pyrolysis peaks were tentatively identified as organic compounds derived from tyrosine and tryptophan. The use of a nitrogen-selective detector in conjunction with the FID and measurement of peak retention times by computer on three different types of columns permitted confirmations of peak identity.
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PMID:Pyrolysis gas chromatography of enzymes. 73 Aug 12

The preparation of benzylated covalently cross-linked Sepharose 2B is described. Such gel was analyzed for its degree of substitution, and gels with three different degrees of substitution were used in chromatographic experiments with dextranase, alpha-amylase, lactate dehydrogenase, alpha-chymotrypsin and trypsin. Yields and chromatographic patterns for different eluting systems were determined. It was found that gradients combining an increase in ethylene glycol concentration with a decrease in salt concentration gave better results than did pure salt gradients. No denaturation was observed for dextranase or alpha-amylase, but the other enzymes tested were partly denatured. The most severe denaturation was observed for lactate dehydrogenase desorbed from the highest substituted gels, although the enzyme was highly active in the adsorbed state. The results and the use of amphophilic gels are discussed.
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PMID:Agarderivatives for chromatography, electrophoresis and gel-bound enzymes. IV. Benzylated dibromopropanol cross-linked sepharose as an amphophilic gel for hydrophobic salting-out chromatography of enzymes with special emphasis on denaturing risks. 115 15

We devised a method for assaying serum lactate dehydrogenase isoenzyme 1 (LD-1) activity specifically by preincubation with alpha-chymotrypsin and guanidine. Cleavage of phenylalanine bonds in the loop of A and B subunits of LD-3, LD-4, and LD-5 isoenzymes (residues 117-119) by incubation with alpha-chymotrypsin for a short time completely inactivated these isoenzymes and partially inactivated LD-2. Addition of guanidine (0.50 mol/L, pH 7.8) to the incubation mixture containing the chymotrypsin completed the inactivation of LD-2. As much as 4000 U/L of LD-2, LD-3, LD-4, and LD-5 were inactivated, whereas LD-1 was affected only slightly. Results by this method (y) correlated well with those by the Roche Isomune immunochemical LD-1 method (x): y = 0.98 x -0.11, r = 0.99 (n = 60). Within-run CVs were 0.5-2.5%. Several common interferents had no effect. In 500 healthy people, serum LD-1 ranged between 66 and 130 U/L, with a mean +/- SD of 88 +/- 15 U/L.
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PMID:Specific assay of serum lactate dehydrogenase isoenzyme 1 by proteolysis with alpha-chymotrypsin and protein denaturation. 142 10

Limited proteolysis of phospholipid complexes of heart and muscle bovine lactate dehydrogenase by trypsin and chymotrypsin has been studied under nondenaturing condition at pH 7.5. Chymotrypsin cleaves the polypeptide chain of heart and muscle lactate dehydrogenase into two principal fragments and LDH subunits were protected by lipids towards the proteinase attack. Enzymatic activity of heart and muscle lactate dehydrogenase was abolished by limited proteolytic cleavage. In complexes, both isoenzymes were protected against proteinases attack by lipids.
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PMID:Limited proteolysis of bovine muscle and heart lactate dehydrogenase is inhibited by phospholipid liposome interaction. 239 38

A human hepatoma cell line, associated with thorotrast exposure, from an hepatitis B marker-negative patient was established as a permanent cell line (Mz-Hep-1) in tissue culture. Histology of the primary tumor, as well as phase contrast, transmission and scanning electron microscopy of the cultured cells showed typical characteristics of liver cells. Mz-Hep-1 cells secreted complement components (C2, C3, C4), carcinoembryonic antigen, lactate dehydrogenase, chymotrypsin, haptoglobin and retinol-binding protein and expressed HLA-, transferrin-, blood group B-related determinants and complement component C5 and carcinoembryonic antigen on their cell surface. Mz-Hep-1 cells represent the first human hepatoma cell line, which is strongly associated with a carcinogen.
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PMID:Hepatocellular carcinoma after thorotrast exposure: establishment of a new cell line (Mz-Hep-1). 241 35

Rat parotid cells were permeabilized with digitonin to examine their secretory dynamics. Cells were isolated by a modification of the method previously described by Hootman [1985). J. Biol. Chem. 260, 4186-4194) in which alpha-chymotrypsin was included. The final preparation consisted of approx. 40-60% single cells. The cells were 85-90% viable by trypan blue exclusion and secreted amylase when stimulated with isoproterenol. Digitonin (2 or 5 microM) was sufficient for permeabilization while 2 microM digitonin was somewhat more effective in maintaining cell integrity as indicated by lactate dehydrogenase release. Digitonin had minimal effects on intracellular granules in the whole cell and was, thus, relatively selective. The response of digitonin-permeabilized cells to calcium (without secretagogues) in the incubation medium was monitored by amylase release. For a wide range of applied free calcium concentrations (1 X 10(-7) M to 10(-4) M) a statistically significant increase in amylase secretion was observed. Control cells did not release amylase to a similar extent without secretagogue. Cyclic AMP (50 microM) significantly enhanced amylase secretion from digitonin-treated cells at all concentrations of free calcium tested. Neither calcium nor cyclic AMP alone was sufficient to stimulate maximal amylase release. Our results provide direct evidence for a model in which calcium and cyclic AMP work on separate pathways as interacting regulators of exocytosis.
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PMID:The effect of calcium and cyclic AMP on amylase release in digitonin-permeabilized parotid gland cells. 243 31

The progressive stabilization of fibrinogen binding to ADP-treated platelets has been well described, but the nature of this interaction remains obscure. In the present study, irreversibly bound fibrinogen was defined as that fraction of bound iodinated fibrinogen that failed to dissociate from stimulated human gel-filtered platelets within 10 min of adding 10 mM ethylenediaminetetraacetic acid. It represented 16 +/- 11% (mean +/- SD, n = 10) of fibrinogen bound to ADP-treated platelets after 1 min and 52 +/- 11% of fibrinogen bound to these platelets after 60 min. Similar results were obtained if platelets were stimulated with purified human thrombin (0.1 U/ml) or epinephrine (10 microM). Irreversible fibrinogen binding was significantly reduced at 4 degrees C (27 +/- 9%, mean +/- SD, n = 6) if platelets were preincubated (30 min, 25 degrees C) with 30 micrograms/ml cytochalasin B or D (18 +/- 8%) or stimulated with chymotrypsin (0.5 mg/2-3 X 10(8) platelets) (31 +/- 8%). Formation of irreversible platelet-fibrinogen interactions correlated with the incorporation of actin and actin-binding protein into the Triton X-100-insoluble platelet cytoskeleton and the ability of platelets to retract fibrin clots. Irreversibly bound fibrinogen was available on platelets for digestion by 0.2 U/ml plasmin. The enzyme removed 96 +/- 6% (mean +/- SD, n = 6) of all bound fibrinogen from platelets after 30 min at 25 degrees C. This was not accompanied by significant release of [14C]serotonin or lactate dehydrogenase. Furthermore, platelets incubated with plasmin could bind fibrinogen normally after the enzyme had been neutralized with aprotinin.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Examination of irreversible platelet-fibrinogen interactions. 315 13

A series of peptides based on the structure of the proteinase inhibitor chymostatin were tested for their toxicity and ability to suppress protein degradation in the isolated mouse diaphragm. The inhibitory activities of the analogues were very similar, in marked contrast to their disparate abilities as inhibitors of chymotrypsin. Toxicity was determined by measurement of the rates of protein synthesis and of leakage of lactate dehydrogenase into the incubation medium. No significant toxicity was measurable at concentrations of inhibitor that were effective at suppressing proteolysis. The structural features of the chymostatin molecule may be less than optimal for suppression of proteolysis in muscle.
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PMID:The effect of synthetic analogues of chymostatin upon protein degradation in isolated skeletal muscle. 389 8


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