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)

Endotoxin protein, a novel mouse B-lymphocyte mitogen, is a hydrophobic acidic compound composed of approximately 85% protein and 2.2% glucosamine, but no 2-keto-3-deoxyoctonate. Endotoxin protein also contains lipid, and analysis of the fatty acids in this material demonstrated the presence of beta-hydroxymyristate, a marker for lipid A. In addition, analysis of endotoxin protein by polyacrylamide gel electrophoresis showed that it is heterogeneous, containing four or five major polypeptides, depending upon the bacterial species from which it was isolated. The mitogenicity of endotoxin protein was diminished by alkaline hydrolysis, but not by treatment with hydrochloric or acetic acid. Furthermore, its activity was resistant to digestion with trypsin, chymotrypsin, and pronase and was only partially degraded by papain.
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PMID:Characterization of the chemical and physical properties of a novel B-lymphocyte activator, endotoxin protein. 31 5

The receptors for aggregated immunoglobulin G (IgG) (an Fc receptor) and for ristocetin-von Willebrand factor on human platelets were studied by means of various modifications of the platelet surface. The expression of these receptors was measured by the agglutination of platelets to ristocetin in the presence of von Willebrand factor, which is part of the factor VIII complex, and by the binding of aggregated IgG coupled to 3H-labelled diazobenzene. Treatment of platelets with chymotrypsin, trypsin, papain and pronase which removed protein and glycoprotein from the platelet under conditions where the release reaction was inhibited caused loss of the expression of the receptor for ristocetin-von Willebrand factor and an enhancement of that for aggregated IgG. Induction of membrane changes with ADP and of the release reaction with the ionophore A23187 abolished agglutination to ristocentin-von Willebrand factor but did not alter the receptor for aggregated IgC. Possible contributions of unspecific membrane changes, produced by protease treatment of platelets, to the modification of receptor expression were eliminated by the use of formaldehyde-treated platelets. Trypsin, papain and pronase destroyed the ability of these platelets to agglutinate to ristocetin-von Willebrand factor but produced no change in the binding of aggregated IgC. Therefore, the receptor for ristocetin-von Willebrand factor is truly sensitive to proteolysis while the Fc receptor is not, but is partially masked by protease-sensitive material.
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PMID:A comparative study of the effect of modification of the surface of human platelets on the receptors for aggregated immunoglobulins and for ristocentin-von Willebrand factor. 31 30

A rapid and convenient method for peptide mapping of proteins has been developed. The technique, which is especially suitable for analysis of proteins that have been isolated from gels containg sodium dodecyl sulfate, involves partial enzymatic proteolysis in the presence of sodium dodecyl sulfate and analysis of the cleavage products by polyacrylamide gel electrophoresis. The pattern of peptide fragments produced is characteristic of the protein substrate and the proteolytic enzyme and is highly reproducible. Several common proteases have been used including chymotrypsin, Staphylococcus aureus protease, and papain.
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PMID:Peptide mapping by limited proteolysis in sodium dodecyl sulfate and analysis by gel electrophoresis. 32 Feb

Effects of treatments with proteolytic enzymes and protein-modifying reagents on flocculation of brewer's yeast IFO 2018 were investigated. The floc-forming ability of the yeast cells was irreversibly eliminated by treatment with papain, trypsin, chymotrypsin or pepsin, indicating that certain proteins on the cell surface participate in the yeast flocculation. Chemical modification with reagents, known to act on disulfide bridges, carboxyl and/or phosphate groups, phenolic groups, amino groups, and imidazole groups, also destroyed the ability to flocculate, although in some cases a high concentration (8 M) of urea was necessary in addition to protein-modifying reagents. Thus, it is suggested strongly that these functional groups of amino acid residues of the proteins are essential for the floc-forming ability of brewer's yeast cells.
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PMID:Effect of chemical modification of cell surface components of a brewer's yeast on the floc-forming ability. 33 19

Highly purified, papain-solubilized HLA-A, -B, and -C antigens comprising a mixture of a great number of allelic forms from at least three loci have been fragmented by limited proteolysis, acid cleavage, and cyanogen bromide treatment. Limited proteolysis of 125I-labeled HLA-A, -B, and -C antigens with trypsin, chymotrypsin, thermolysin, and pepsin resulted in the production of two large fragments. One fragment was associated with beta 2-microglobulin and contained all of the carbohydrate. The other fragment, which had a molecular weight of about 13,000, is most probably derived from the COOH-terminal part of the heavy chain. Acid cleavage of the HLA antigen heavy chain gave rise to two main fragments with molecular weights of 22,000 and 11,000. Both fragments contained disulfide bonds. Two minor components, representing further cleavage products of the 22,000-dalton fragment, were also observed. Cleavage of the HLA antigen heavy chain at methionyl residues gave rise to one carbohydrate-containing, cysteine-free 14,000-dalton fragment and one 20,000-dalton fragment that contained all cysteines but no carbohydrate. NH2-terminal amino acid sequence analyses demonstrated that the 22,000-dalton acid cleavage fragment and the 14,000-dalton cyanogen bromide fragment were derived from the NH2-terminal part of the HLA antigen heavy chain.
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PMID:Fragmentation of the human transplantation antigen heavy chain by limited proteolysis, acid cleavage, and cyanogen bromide treatment. 37 76

Phosphoenolpyruvate carboxylase from Escherichia coli W was treated with ten proteases, and the effects of the treatments on the enzyme activity and sensitivity to effectors were investigated. Proteases such as trypsin, alpha-chymotrypsin, papain, and subtilisin inactivated the enzyme, whereas elastase, carboxypeptidase Y and leucine aminopeptidase had no effect on the enzyme activity. Elastase and carboxypeptidase Y, however, inactivated the enzyme in the presence of 1 m urea. Subtilisin and alpha-chymotrypsin caused not only inactivation of the enzyme but also a significant desensitization to the effectors. DL-Phospholactate, a potent competitive inhibitor, markedly protected the enzyme from inactivation by subtilisin but did not protect it from desensitization to the effectors. Acetyl-CoA, fructose 1, 6-bisphosphate, and GTP-the allosteric activators--protected the enzyme from subtilisin inactivation, while laurate, the other allosteric activator, accelerated the inactivation. These activators did not protect the enzyme from desensitization to themselves. In contrast, modification with subtilisin in the present of l-aspartate, the allosteric inhibitor, caused an apparent transient activation of the enzyme. The enzyme modified in the presence of L-aspartate retained its sensitivity to L-aspartate, but the sensitivities to the other effectors were reduced to about one-half their initial values. Based on these results, a possible mode of desensitization of the enzyme by subtilisin modification and the possible existence of a multiplicity of conformational states of the enzyme, induced upon binding with the various effectors, are discussed.
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PMID:Phosphoenolpyruvate carboxylase of Escherichia coli. Effect of proteolytic modification on the catalytic and regulatory propties. 38 5

Proteinase k, a seryl-protease obtained from Tritirachium album, is able to specifically hydrolyze N-blocked aminoacyl transfer ribonucleic acids (tRNAs). The blocked amino acid is released, and the tRNA molecule remains able to be recharged by its cogante amino acid. Aminoacyl-tRNAs are highly resistant to hydrolysis by the protease. This activity is not due to contamination of the protease preparation. A commercial protease from Streptomyces griseus displayed a similar activity, while trypsin, chymotrypsin, and papain unspecifically hydrolyzed all charged tRNAs tested. The characteristics of the hydrolysis performed by proteinase k closely resemble the peptidyl-tRNA hydrolase activity described in different cells as a scavenger for the peptidyl-tRNA that eventually falls from the polysomes. Out results warn about a hasty identification of any N-blocked aminoacyl-tRNA hydrolase activity in the cytoplasm as an independent peptidyl-tRNA hydrolase.
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PMID:Peptidyl transfer ribonucleic acid hydrolase activity of proteinase k. 38 46

The acetylcholine receptor from Torpedo californica electroplax was purified approximately 100-fold by affinity chromatography on alpha-neurotoxin-Sepharose 6B. Four putative subunits (alpha, beta, gamma, delta) of apparent molecular weights of 43,000, 52,000, 58,000, and 63,000 were found when the purified material was analyzed by sodium dodecyl sulfate (NaDodSO4) gel electrophoresis. In some preparations, however, the amount of the gamma polypeptide was small. The presence of N-ethylmaleimide throughout the purification procedure greatly enhanced the amount of the gamma chain. To investigate the possibility that the putative subunits may be structurally related, they were isolated by preparative NaDodSO4 gel electrophoresis and subjected to peptide mapping analyses. The patterns of fragments generated by Staphylococcus aureus V8 protease, papain, or chymotrypsin were different for each of the polypeptides. Thus, it is unlikely that they are derivatives of each other.
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PMID:Comparison of the subunits of Torpedo californica acetylcholine receptor by peptide mapping. 42 Jul 86

The protein moiety of squid (Watasenia scintillans) rhodopsin has been shown to have a molecular weight of 46 800 by means of amino acid analysis. This value was comparable to the value (51 000) obtained from SDS-polyacrylamide gel electrophoresis. After the squid eyes were incubated at 10 degrees C for 8 days, the rhodopsin showed a molecular weight of 39 000 on electrophoresis. The smaller molecular weight was ascertained by amino acid analysis of the rhodopsin; and may result from autolysis by the lysosomal enzyme. The rhodopsin in rhabdomeric membranes and in detergent solution was treated with chymotrypsin, papain or subtilisin. These enzymes first produced the 39 000 dalton rhodopsin and then cleaved this into the 25 000 and 14 000 dalton peptides without bleaching. The rhodopsin was attacked by proteases and readily lost an approx. 12 000 dalton peptide portion. This portion included the COOH-terminal and was rich in glutamic acid, proline, glycine, alanine and tyrosine residues.
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PMID:Molecular weight and structural studies on cephalopod rhodopsin. 46 26

Extracellular chymotrypsin cleaves the 95 000 dalton protein that migrates in band 3 of SDS-polyacrylamide gel electropherograms of the erythrocyte membrane into fragments of 60 000 and 35 000 daltons, but not further. Minor components of band 3 that remain at the original 95 000 dalton location may be eluted from the membrane by 0.1 N NaOH, indicating that, in contrast to the major component and the chymotryptic fragments, they are not integral membrane constituents. Incubation at neutral pH of chymotrypsinized erythrocytes with the bifunctional anion transport inhibitor 4,4'-diisothiocyano dihydrostilbene-2,2'-disulfonic acid results in covalent binding of that inhibitor primarily to the 60 000 dalton fragment and some cross-linking of the 60 000 dalton fragment with the 35 000 dalton fragment. Increasing the pH to 9.5 leads to a cross-linking of virtually all of the pairs of chymotryptic fragments and thus to a reconstitution of band 3 with its typical diffuse appearance in the 95 000 dalton region of the SDS-polyacrylamide gels. This indicates that (1) each integral 95 000 dalton protein molecule is capable of binding at least one 4,4'-diisothiocyano dihydrostilbene-2,2'-disulfonic acid molecule; (2) the 35 000 dalton fragment, though it is only weakly stained with Coomassie blue, is present in an amount that is equimolar with that of the 60 000 dalton fragment. Since the number of 4,4'-diisothiocyano dihydrostilbene-2,2'-disulfonic acid binding sites on the protein in band 3/cell is known to be close to the number of band 3 molecules/cell, it is suggested that the cross-linking takes place at a region of the band 3 molecule that is involved in the control of anion transport, Like chymotrypsin, papain digests the band 3 protein from the outer membrane surface. Unlike chymotrypsin, however, papain digestion results in an inhibition of anion exchange. Papain produces a major fragment of 60 000 daltons that differs from the major chymotryptic fragment by at most six amino acid residues. The only detectable difference between the noninhibitory action of chymotrypsin and the inhibitory action of papain on the band 3 protein is that papain is capable of partially digesting the 35000 dalton fragment. No reconstitution of band 3 by cross-linking of the fragments with 4,4'-diisothiocyano dihydrostilbene-2,2'-disulfonic acid can be achieved. Since the 35 000 dalton fragment reacts with one of the two reactive groups of 4,4'-diisothiocyano dihydrostilbene-2,2'-disulfonic acid and is also susceptible to digestion by the inhibitory papain, we suggest that a portion of this peptide participates, together with a portion of the 60 000 dalton fragment, in the control anion transport.
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PMID:Anion transport across the erythrocyte membrane, in situ proteolysis of band 3 protein, and cross-linking of proteolytic fragments by 4,4'-diisothiocyano dihydrostilbene-2,2'-disulfonate. 48 55


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