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:3.4.21.1 (chymotrypsin)
10,938 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The radiation yeilds of unfolding (Gconf) determined by the method of tryptophan fluorescence coincide with the radiation yields of proteolytic inactivation (Gin) for chymotrypsin-like (CT-like) enzymes on irradiation in air, both in solution and in the dry state with futher dissolution at pH7. It can be supposed that the unfolding is the main process determining the proteolytic gamma-inactivation of CT-like enzymes. It was also shown that the transition of chymotrypsin and trypsin gamma-irradiated at acid pH to neutral pH is an additional action, leading to unfolding of part of the molecules.
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PMID:Gamma-irradiated chymotrypsin-like proteins. II. Connection between inactivation and structural changes. 1 28

The G-200 flow-through fraction of the extract of sea urchin eggs contained a complex form of glutathione reductase (GR) [EC 1.6.4.2]. The complex was unstable and gradually dissociated with ain increase in GR activity. The activation was facilitated by high concentrations of EDTA, KCI or (NH4)2SO4. The rate of activation by salts was apparently dependent on the ionic strength. The complex form was also activated rather quickly by treatment with proteinases such as trypsin [EC 3.4.21.4], alpha-chymotrypsin [EC 3.4.21.1] or subtilisin [EC 3.4.21.14]. Trypsin caused the complex to release the free form of GR. Even after trypsin treatment, little change was observed in the dependence of the GR activity on GSSG or NADPH concentration. The GR activity of the complex form was not inhibited at all by 0.2 mM N-ethylmaleimide (NEM) in the presence of GSSG, but was reduced to 3% in the presence of NADPH. When excess NEM was sequestered with GSH, the NEM-treated complex form was strikingly activated by trypsin, while no activation was detected with the free form of enzyme pretreated with NEM. These results suggest that the active site of GR in the complex form is largely masked by a polypeptide moiety of theinhbitiory component.
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PMID:Glutathione reductase in the sea urchin egg. III. Activation of the complex form by proteinases. 1 74

Methoxypolyethylene glycols of 1900 daltons (PEG-1900) or 5000 daltons (PEG-5000) were covalently attached to bovine liver catalase using 2,4,6-trichloro-s-triazine as the coupling agent. Rabbits were immunized by the intravenous and intramuscular routes with catalase modified by covalent attachment of PEG-1900 to 43% of the amino groups (PEG-1900-catalase). The intravenous antiserum did not yield detectable antibodies against PEG-1900-catalase or native catalase, as determined by Ouchterlony and complement fixation methods, whereas the intramuscular antiserum contained antibodies to both PEG-1900-catalase and catalase. PEG-1900 did not react with either antiserum. Catalase was prepared in which PEG-5000 was attached to 40% of the amino groups (PEG-5000-catalase). This catalase preparation did not react with either antiserum. PEG-1900-catalase retained 93% of its enzymatic activity; PEG-5000-catalase retained 95%. PEG-5000-catalase resisted digestion by trypsin, chymotrypsin, and a protease from Streptomyces griseus. PEG-1900-catalase and PEG-5000-catalase exhibited enhanced circulating lives in the blood of acatalasemic mice during repetitive intravenous injections. No evidence was seen of an immune response to injections of the modified enzymes. Mice injected repetitively with PEG-5000-catalase remained immune competent for unmodieied catalase, and no evidence of tissue or organ damage was seen.
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PMID:Effect of covalent attachment of polyethylene glycol on immunogenicity and circulating life of bovine liver catalase. 1 7

Myosin from rabbit stomach was highly purified by ammonium sulfate fractionation in the presence of ATP and MgCl2, ultracentrifugation and Sepharose 4B chromatography. The myosin composed of one heavy and two light chains as determined by SDS-gel electrophoresis. The molecular weights of the light chains were the same as those of gizzard myosin, about 20,000 and 17,000, respectively. The pH-activity curve and the KCl concentration dependency of Ca-ATPase of the stomach myosin were similar to those of other smooth muscle myosins. The stomach myosin was more resistant to pepsin digestion than skeletal myosin. Other proteolytic enzymes, trypsin, chymotrypsin, papain, and nagarse, digested the myosin in the same way as skeletal myosin.
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PMID:Purification and some properties of rabbit stomach myosin. 1 37

The immobilization of alpha-chymotrypsin, trypsin and invertase on hydrated oxides of tin, titanium and aluminium was investigated. The degree at which the enzymes were bound upon immobilization was 83.2-2.6%. The amount of bound proteins was 64.2 mg/g carrier. The specific activity of enzymes reached the highest level in the case of hydrated tin oxide and amounted to 76.8%, 49.9% and 99.6%, of activity of native alpha-chymotrypsin, trypsin and invertase, respectively. The thermal stability of immobilized proteases was considerably higher and that of immobilized invertase was significantly lower than that of native enzymes. The pH optimum of immobilized enzymes shifted by 0.6-2.6 units towards the alkaline region.
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PMID:[Enzyme immobilization on hydrated oxides of transition metals and aluminum]. 1 37

Serum-free conditioned medium from human lung obtained at autopsy provides a rich source of colony stimulating factor which stimulates granulocytic and macrophagic colony growth in both mouse and human bone marrow. The appearance of the factor is enhanced by endotoxin and inhibited by either puromycin or actinomycin D. Human lung colony stimulating factor is stable at the pH range of 6.5-10 and temperature of 56 degrees C for 30 min. It is resistant to trypsin and neuraminidase but is sensitive to subtilisin, chymotrypsin and periodate. It shows heterogeneity on Sephadex gel filtration with two activity peaks having molecular weight of 200 000 and 40 000, respectively. Upon gel electrophoresis, human lung colony stimulating factor migrates in the alpha-globulin post-albumin region. Using the combination procedures of hydroxyapatite chromatography and preparative polyacrylamide gel electrophoresis a 600-fold purification was achieved with a final specific activity of 6-10(5) units per mg protein. The purified colony stimulating factor is very labile; however, the activity can be stabilized by the addition of gelatin or bovine serum albumin at the concentration of 0.1% and 0.2 mg/ml, respectively.
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PMID:The isolation and characterization of a colony stimulating factor from human lung. 2 Jan 57

Cobalamin (Cbl; vitamin B(12)) malabsorption in pancreatic insufficiency can be partially corrected by bicarbonate and completely corrected by pancreatic proteases but the mechanisms involved are unknown. Because saliva contains enough R-type Cbl-binding protein (R protein) to bind all of the dietary and biliary Cbl, it is possible that R protein acts as an inhibitor of Cbl absorption and that pancreatic proteases are required to alter R protein and prevent such inhibition. To test this hypothesis we studied the ability of R protein and intrinsic factor (IF) to compete for Cbl binding and ability of pancreatic proteases to alter this competition. Human salivary R protein bound Cbl with affinities that were 50- and 3-fold higher than those of human IF at pH 2 and 8, respectively. Cbl bound to IF was transferred to an equal amount of R protein with t((1/2))'s of 2 and 90 min at pH 2 and 8, respectively, and within several hours respective ratios of R protein-Cbl/IF-Cbl of 50 and 2 were observed. Cbl bound to R protein was not transferred to IF at either pH 2 or 8. Incubation of R protein with pancreatic proteases at pH 8 led to a 150-fold decrease in its affinity for Cbl. Incubation of R protein-Cbl with pancreatic proteases led to complete transfer of Cbl to IF within 10 min. Gel filtration studies with R protein-[(57)Co]Cbl and (125)I-R protein showed that pancreatic proteases partially degraded R protein. Pancreatic proteases differed in their ability to effect these changes with trypsin > chymotrypsin > elastase. Pancreatic proteases did not alter IF in any of the parameters mentioned above. Pepsin failed to alter either R protein or IF. THESE STUDIES SUGGEST THE FOLLOWING: (a) that Cbl is bound almost exclusively to R protein in the acid milieu of the stomach, rather than to IF as has been assumed previously; (b) that Cbl remains bound to R protein in the slightly alkaline environment of the intestine until pancreatic proteases partially degrade R protein and enable Cbl to become bound exclusively to IF; and (c) that the primary defect in Cbl absorption in pancreatic insufficiency is a lack of pancreatic proteases and a failure to alter R protein and effect the transfer of Cbl to IF. These studies also suggest that the partial correction of Cbl malabsorption observed with bicarbonate is due to neutralization of gastric HCl, since at slightly alkaline, pH IF can partially compete with R protein for the initial binding and retention of Cbl.
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PMID:Effect of proteolytic enzymes on the binding of cobalamin to R protein and intrinsic factor. In vitro evidence that a failure to partially degrade R protein is responsible for cobalamin malabsorption in pancreatic insufficiency. 2 56

The Neurospora crassa glycogen synthase (UDPglucose:glycogen 4-alpha-glucosyltransferase, EC 2.4.1.11) was purified to electrophoretic homogeneity by a procedure involving ultracentrifugation, DEAE-cellulose column chromatography, (NH4)2SO4 fractionation and 3-aminopropyl-Sepharose column chromatography. The final purified enzyme preparation was almost entirely dependent on glucose-6-P and had a specific activity of 6.9 units per mg of protein. The subunit molecular weight of the glycogen synthase was determined by electrophoresis in sodium dodecyl sulfate-polyacrylamide gel to be 88 000--90 000. The native enzyme was shown to have a molecular weight of 270 000 as determined by sucrose density gradient centrifugation. Thus, the glucose-6-P-dependent form of the N. crassa glycogen synthase can exist as trimer of the subunit. Limited proteolysis with trypsin or chymotrypsin converted the glucose-6-P-dependent form of the enzyme into an apparent glucose-6-P-independent form. The enzyme was shown to catalyze transfer of glucose from UDPglucose to glycogen as well as to its phosphorylase limit dextrin, but not to its beta-amylase limit dextrin. Moreover, glucose, maltose and maltotriose were not active as acceptors.
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PMID:Biosynthesis of glycogen in Neurospora crassa. Purification and properties of the UDPglucose:glycogen 4-alpha-glucosyltransferase. 2 41

Soybean Bowman-Birk inhibitor, a double-headed inhibitor of trypsin and alpha-chymotrypsin, was treated with cyanogen bromide and then pepsin to yield two inhibitory active fragments. Structural investigation showed that one of the fragments was derived from the trypsin inhibitory domain and the other from the chymotrypsin inhibitory domain of the inhibitor. In contrast to the unusual stability of the native inhibitor, the separated domains were less stable and could be inactivated with excess proteinases. These results suggest that the legume double-headed inhibitors acquired their unusual stability by duplicating an ancestral single-headed structure.
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PMID:Studies on soybean trypsin inhibitors. XIII. Preparation and characterization of active fragments from Bowman-Birk proteinase inhibitor. 2 70

Modified trypsin kallikrein inhibitor (I*), with the reactive-site peptide bond Lys-15--Ala-16 split, reacts with alpha-chymotrypsin (E) via an intermediate X to the stable tetrahedral complex C:E + I in equilibrium X leads to C. Formation X constitutes a fast pre-equilibrium (equilibrium constant Kx = 7 X 10(-5) M, association rate constant kx = 4 X 10(3)M-1s-1) to the slow reaction X leads to C (rate constant kc = 2 X 10(-3) s-1), all values at pH 7.5. No intermediate X is observed when alpha-chymotrypsin reacts with I*-OMe in which the carboxyl group of Lys-15 is esterified by methanol. This observation as well as the different pH dependence of the overall association rate constants in the case of I* and I*-OMe indicate tha formation of X precedes formation of the acyl enzyme in the catalytic pathway. The data are compared to the similar results obtained with beta-trypsin and I* or I*-OMe.
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PMID:Kinetics of the interaction of alpha-chymotrypsin with trypsin kallikrein inhibitor (Kunitz) in which the reactive-site peptide bond Lys-15--Ala-16 is split. 2 64


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