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)

Hydrolysis of the membrane proteins and phospholipid headgroups of rat liver rough endoplasmic reticulum membranes showed that the ribosomal binding sites involve membrane proteins susceptible to low concentrations of trypsin, chymotrypsin, and papain. Three membrane proteins having molecular weights of 120 000, 93 000 and 36 000 are found to be altered by trypsin and chymotrypsin treatment. Also the polar headgroup of phosphatidylinositol appears to play a role in the binding process.
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PMID:The role of membrane proteins and phospholipids in the interaction of ribosomes with endoplasmic reticulum membranes. 118 90

Treatment of purified tryptophanyl-tRNA synthetase with either chymotrypsin, papain, subtilisin or elastase converts all the enzyme into a high-molecular-weight intermediate. This protease-resistant core molecule has the same dimeric structure as the native protein and possesses the ability to bind substrates (tryptophan, ATP and tRNATrp) but is catalytically inactive. The monomer molecular weight of the protease-treated enzyme is 39000 compared to 54000 for the intact molecule. Chemical studies indicate that proteases excise the amino-terminal part of the polypeptide chain. It has been demonstrated previously that removal of a 13000-dalton fragment from the amino-terminal region of the tryptophanyl-tRNA synthetase converts the native enzyme to another active form. Cleavage of 20 additional amino acids produces the inactive protease-resistant core.
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PMID:Limited proteolysis of tryptophanyl-tRNA synthetase from beef pancreas. 124 79

Band 3 is the major, membrane-spanning, approximately90 000 dalton polypeptide of the human erythrocyte membrane. To facilitate the analysis of its structural integration into the membrane, we have cleaved this protein in situ into large fragments and ascertained their disposition. Digestion of intact cells with chymotrypsin yielded band 3 fragments with apparent molecular weights of 38 000 and 55 000. Both fragments resisted elution by NaOH and acetic acid, suggesting that they are anchored in the apolar core of the membrane. Both pieces communicate with the extracellular space, and the 55 000 dalton species extends to the cytoplasmic surface as well. Digestion of unsealed ghosts with chymotrypsin produced a hydrophobic 17 000 dalton species, a segment of the 55 000 dalton fragment, which spans and is firmly anchored in the core of the membrane. Trypsin and papain at low concentration generated integral band 3 fragments of 52 000 daltons and released major band 3 fragments of less than or equal to 41 000 daltons from the cytoplasmic side of the membrane. The latter water-soluble polypeptides remained associated in discrete complexes which retained the capacity to bind glyceraldehyde-3-phosphate dehydrogenase. An interchain disulfide bond, which can be induced only at the cytoplasmic surface, cross-linked intact band 3, and certain of its water-soluble fragments. Finally, fragments of 23 000 daltons were generated from the innersurface domain by reacting disulfide-linked band 3 dimers with cyanide or reduced polypeptides with 2-nitro-5-thiocyanobenzoate. A provisional ordering of these fragments is proposed.
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PMID:Proteolytic dissection of band 3, the predominant transmembrane polypeptide of the human erythrocyte membrane. 125 33

The releases of proteins, maltase, lactase, sucrase, trehalase, alkaline phosphatase, gamma-glutamyltransferase and leucylnaphthylamide-hydrolyzing activity from human intestinal brush bborder membrane vesicles by various enzymes (especially pancreatic proteases) have been studied. The brush border membrane enzymes are not solubilized by digestion with trypsin and chymotrypsin but are largely released after treatment with papain or elastase. Most of the enzymes are fully active after the proteolytic treatment. All proteins released by papain and elastase have been identified by electrophoresis to already known intestinal hydrolases. Electron microscopy of brush border membrane vesicles demonstrates "knob-like" structures (particles) attached to the external side of the membrane. During papain treatment, enzyme removal runs parallel with the disappearance of the particles. During elastase treatment it is not possible to correlate the release of the enzymic activities with the removal of the particles. The results indicate that most of the intestinal hydrolases are surface components attached to the external side of the membrane. They are in accord with the concept that the brush border membrane enzymes are organized within the membrane in a mosaic-like pattern.
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PMID:Enzymic solubilization of the human intestinal brush border membrane enzymes. 127 90

A marked increase in water permeability can be induced in Xenopus oocytes by injection of mRNA from tissues that express water channels, suggesting that the water channel is a protein. In view of this and previous reports which showed that proteinases may interfere with mercurial inhibition of water transport in red blood cells (RBC), we examined the influence of trypsin, chymotrypsin, papain, pronase, subtilisin and thermolysin on water permeability as well as on ATPase activity, H(+)-pump, passive H+ conductance, and Na+/H+ exchange in apical brush-border vesicles (BBMV) and endosomal (EV) vesicles from rat renal cortex. H+ transport was measured by Acridine orange fluorescence quenching and water transport by stopped-flow light scattering. As measured by potential-driven H+ accumulation in BBMV and EV, proteinase treatment had little effect on vesicle integrity. In BBMV, ecto-ATPase activity was inhibited by 15-30%, Na+/H+ exchange by 20-55%, and H+ conductance was unchanged. Osmotic water permeability (Pf) was 570 microns/s and was inhibited 85-90% by 0.6 mM HgCl2; proteinase treatment did not affect Pf or the HgCl2 inhibition. In EV, NEM-sensitive H+ accumulation and ATPase activity were inhibited by greater than 95%. Pf (140 microns/s) and HgCl2 inhibition (75-85%) were not influenced by proteinase treatment. SDS-PAGE showed selective digestion of multiple polypeptides by proteinases. These results confirm the presence of water channels in BBMV and EV and demonstrate selective inhibition of ATPase function and Na+/H+ exchange by proteinase digestion. The lack of effect of proteinases on water transport by mercurials. We conclude that the water channel may be a small integral membrane protein which, unlike the H(+)-ATPase and Na+/H+ exchanger, has no functionally important membrane domains that are sensitive to proteolysis.
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PMID:Proteinases inhibit H(+)-ATPase and Na+/H+ exchange but not water transport in apical and endosomal membranes from rat proximal tubule. 130 58

An inhibitory protein for the 20S proteasome (also known as macropain, the multicatalytic proteinase complex and 20S proteinase) has been purified from bovine red blood cells. The inhibitor has an apparent molecular weight of 31,000 on SDS-PAGE and appears to form multimers under nondenaturing conditions. This protein inhibited all three of the putatively distinct catalytic activities of proteasome A (the active form of the proteinase) characterized by the hydrolysis of synthetic peptides such as Z-VLR-MNA, Z-GGL-AMC or Suc-LLVY-AMC and Z-LLE-beta NA. The inhibitor also prevented the hydrolysis of large protein substrates such as casein, lysozyme and bovine serum albumin. Proteasome L (the latent form of the proteinase) does not degrade these large protein substrates, but does hydrolyze the three synthetic peptides at rates similar to those by proteasome A. The inhibitor inhibited only two of these peptidase activities of proteasome L (hydrolysis of Z-GGL-AMC and of Z-LLE-beta NA or Suc-LLVY-AMC); it had no effect on the hydrolysis of Z-VLR-MNA. The inhibitor was specific for inhibition of the proteasome and had no effect on the activity of any other proteinase tested including trypsin, chymotrypsin, papain, subtilisin and both isoforms of calpain. Kinetic analysis indicates that the inhibitor interacted with the proteasome by a mechanism involving tight-binding. Because the proteasome appears to be a key component of the ATP/ubiquitin-dependent pathway of intracellular protein degradation, the inhibitor may represent an important regulatory protein of this pathway.
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PMID:Purification and characterization of a protein inhibitor of the 20S proteasome (macropain). 131 59

The precursor of Leu-enkephalin, Z-L-TyrGlyGly-L-Phe-L-LeuOEt, was synthesized from amino acid derivatives with three proteinases without the protection of the side chain of L-Tyr. First, Z-GlyGlyOBut and Z-L-TyrGlyGlyOBut were synthesized in quite a high yield, 83% and 99%, in an aqueous/organic biphasic system by papain and alpha-chymotrypsin, respectively. Then, Z-L-Phe-L-LeuOEt was synthesized by thermolysin from Z-L-Phe and L-LeuOEt either in buffer or in a biphasic system; the yields were 95% and 100%, respectively. The synthesis of Z-L-TyrGlyGly-L-Phe-L-LeuOEt from Z-L-TyrGlyGly and L-Phe-L-LeuOEt was performed effectively by thermolysin immobilized on Amberlite XAD-7 in a buffer and in an aqueous/organic biphasic system, as well as in saturated ethyl acetate, while the yield was low in reactions by free thermolysin. In the reaction with the immobilized enzyme (IME) in saturated ethyl acetate, the maximum yield of the precursor of Leu-enkephalin was 68%. The reasons for effective synthesis with IME are: (1) higher concentration of L-Phe-L-LeuOEt inside support, which resulted in rising the rate of the synthesis reaction and protecting the competitive hydrolysis of Z-L-TyrGlyGly by thermolysin, (2) entrapment of the product inside the support where thermolysin could not act in the case of reaction in buffer, and (3) extraction of the product with the organic solvent in the case of reaction in a biphasic system or in saturated organic solvent.
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PMID:Enzymatic synthesis of the precursor of Leu-enkephalin in water-immiscible organic solvent systems. 136 23

Silkworm antitrypsin (sw-AT) isolated from larval hemolymph was limitedly digested by Achromobacter lysylendopeptidase, alpha-chymotrypsin, subtilisin BPN', subtilisin Carlsberg, papain, or Pseudomonas elastase. Each proteinase could cleave specific site(s) around the reactive site identified for the reaction of sw-AT and bovine trypsin. Among these proteinases, only subtilisin BPN' was inhibited by sw-AT, although weakly. By the cleavable amino acid sequence in sw-AT, it was suggested that whether or not these proteinases were inhibited by sw-AT did not solely depend on their substrate specificities. The susceptibility to the attack of proteinase should indicate that this region is exposed on the molecular surface. The amino acid sequence in the COOH-terminal region slightly away from the reactive site in sw-AT had homology with that in the corresponding region of the serine proteinase inhibitor (serpin) group.
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PMID:Limited proteolysis of silkworm antitrypsin by several proteinases. 136 15

P-selectin on platelets and endothelial cells and E-selectin on endothelial cells are leukocyte receptors that recognize lineage-specific carbohydrates on neutrophils and monocytes. The proposed ligands for these receptors contain the Le(x) core and sialic acid. Since other investigators have shown that both E-selectin and P-selectin bind to sialylated Le(x), we evaluated whether E-selectin and P-selectin recognize the same counter-receptor on leukocytes. The interaction of HL60 cells with Chinese hamster ovary (CHO) cells expressing P-selectin or E-selectin was studied. To determine whether a protein component is required in addition to sialyl Le(x) for either P-selectin or E-selectin recognition, HL60 cells or neutrophils were digested with proteases, including chymotrypsin, elastase, proteinase Glu-C, ficin, papain, or thermolysin. Cells treated with these proteases bound E-selectin but not P-selectin. Fucosidase or neuraminidase treatment of HL60 cells markedly decreased binding to both E-selectin- and P-selectin-expressing CHO cells. Growth of HL60 cells in tunicamycin inhibited the ability of these cells to support P-selectin-mediated binding and, to a lesser extent, E-selectin-mediated binding. Purified P-selectin inhibited CHO:P-selectin binding to HL60 cells, but incompletely inhibited CHO:E-selectin binding to HL60 cells. However, purified soluble E-selectin inhibited CHO:P-selectin and CHO:E-selectin binding to HL60 cells equivalently and completely. COS cells, unable to bind to E-selectin or P-selectin, bound E-selectin but not P-selectin upon transfection with alpha-1,3-fucosyltransferase or alpha-1,3/1,4-fucosyltransferase. Similarly, LEC 11 cells expressing sialyl Le(x) bound E-selectin- but not P-selectin-expressing CHO cells. Sambucus nigra lectin, specific for the sialyl-2,6 beta Gal/GalNAc linkage, inhibited P-selectin but not E-selectin binding to HL60 cells. Although sialic acid and Le(x) are components of the P-selectin ligand and the E-selectin ligand, these results indicate that the ligands are related, having overlapping specificities, but are structurally distinct. A protein component containing sialyl Le(x) in proximity to sialyl-2,6 beta Gal structures on the P-selectin ligand may contribute to its specificity for P-selectin.
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PMID:P-selectin and E-selectin. Distinct but overlapping leukocyte ligand specificities. 137 36

The cell-free haemolymph of the mollusc Octopus vulgaris inhibited the proteolytic activity of the thermolysin against the high-molecular-mass substrate hide powder azure. The purified inhibitor was a glycoprotein composed of two identical 180 kDa disulphide-linked subunits. In addition to the inhibition of the metalloproteinase thermolysin, the protein inhibited the serine proteinases human neutrophil elastase, pig pancreatic elastase, bovine chymotrypsin, bovine trypsin and the cysteine proteinase papain. A fraction of the proteinase-inhibitor complex resisted dissociation after denaturation indicating that some of the proteinase molecules became covalently bound. The nucleophile beta-aminopropionitrile decreased the covalent binding of proteinases to the Octopus vulgaris protein, suggesting that this interaction is mediated by an internal thiol ester; the reactivity and the amino acid sequence flanking the reactive residues of the putative thiol ester were consistent with this hypothesis. Bound trypsin remained active against the low-molecular-mass chromatogenic substrate H-D-Pro-Phe-Arg p-nitroanilide and was protected from inhibition by active-site-directed protein inhibitors of trypsin; however, the bound trypsin was readily inhibited by small synthetic inhibitors. This indicates that the inhibition of proteinases is accomplished by steric hindrance. The proteinase-inhibitory activity of this protein is characteristic of inhibition by mammalian alpha-macroglobulins and the presence of a putative thiol ester suggests that the Octopus vulgaris proteinase inhibitor is a homologue of human alpha 2-macroglobulin.
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PMID:Purification and characterization of an alpha-macroglobulin proteinase inhibitor from the mollusc Octopus vulgaris. 137 44


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