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)

Three fenugreek inhibitors (TFI-A8, TFI-N2, and TFI-B2) were isolated from an inhibitor preparation by anion exchange chromatography and subsequent preparative isoelectric focusing using immobilized pH gradients and the canal technique. The purified inhibitors inhibited the enzymes tested differently: TFI-A8 exhibited a high inhibition of trypsin (8.2 mg human trypsin/mg and 8.1 mg bovine trypsin/mg) and a very low inhibition of chymotrypsin (0.8 mg human chymotrypsin/mg and 1.0 mg bovine chymotrypsin/mg). TFI-N2 inhibited the four enzymes to about the same extent (5.0 mg/mg human and 4.1 mg/mg bovine trypsin; 4.9 mg/mg human and 3.7 mg/mg bovine chymotrypsin). TFI-B2 displayed a high inhibition of trypsin (7.5 mg/mg human and 5.1 mg/mg bovine) and a low inhibition of chymotrypsin (1.8 mg/mg human and 1.9 mg/mg bovine). On average, the human enzymes were inhibited better than the bovine ones by the purified inhibitors. The inhibitors contained high amounts of cystine (five or six disulfide bridges per molecule), aspartic acid, threonine, serine and proline, no valine and methionine and two of them also no tryptophan. Their molecular masses were about 6 kDa. Their inclusion into the Bowman-Birk soybean proteinase inhibitor family is discussed.
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PMID:Inhibitors of human and bovine trypsin and chymotrypsin in fenugreek (Trigonella foenum-graecum L.) seeds. Isolation and characterization. 187 34

Brain pyridoxine-5-P oxidase is activated by the tryptophan metabolites 3-hydroxyanthranilate and 3-hydroxykynurenine. 3-Hydroxyanthranilate at concentrations of 0.03 mM relieves the inhibition elicited by accumulation of the substrate pyridoxine-5-P (Ki = 60 microM). The results of fluorometric measurements indicate that four molecules of 3-hydroxyanthranilate bind to the dimeric enzyme (56 kDa) with an association constant of 5.5 x 10(4) M-1. Differential spectral measurements failed to detect any direct interaction between the cofactor FMN and the effector 3-hydroxyanthranilate. These results are consistent with the hypothesis that the effector molecules bind to sites of the dimeric protein distinct from the cofactor site. Limited chymotrypsin digestion of pyridoxine-5-P oxidase yields catalytically active species that are no longer susceptible to activation by 3-hydroxykynurenine. A polypeptide of 16 kDa containing FMN and endowed with full catalytic activity was isolated by ion-exchange chromatography. It is postulated that the structural domain associated with catalytic activity composes approximately one-half of the molecular mass of pyridoxine-5-P oxidase (28 kDa), whereas the remaining portion of the macromolecule contains regulatory binding sites.
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PMID:Catalytic and regulatory properties of native and chymotrypsin-treated pyridoxine-5-phosphate oxidase. 193 34

Trypsin inhibitory activity from the hemolymph of Limulus polyphemus was found to co-purify with coagulogen (the clottable protein in blood coagulation) after acidification, ammonium sulfate precipitation, and gel filtration. Limulus trypsin inhibitor (LTI) was separated from coagulogen by ion-exchange chromatography on carboxymethyl-Sephadex. LTI is an inhibitor of trypsin (Ki = 3.3 nM) on both high and low molecular weight substrates. It also inhibits chymotrypsin but has little or no effect on thrombin, thermolysin, pepsin, or papain, nor does LTI inhibit the proteolytic cascade produced in endotoxin-stimulated Limulus amoebocyte lysate coagulation. Electrophoresis under nonreducing conditions on denaturing polyacrylamide gel yields a doublet migrating with an estimated Mr of 20,000. Under reducing conditions, a single broad band migrates with an estimated Mr of 15,000. The native structure is a monomer of moderate asymmetry with a molecular weight of 16,300 and a so20,w = 1.5(5), as determined by analytical ultracentrifugation. The amino acid composition of LTI yields a calculated molecular weight of 15,680 and a calculated partial specific volume of 0.71(7) ml/g. LTI does not contain methionine, tryptophan, or detectable levels of reducing carbohydrate. The NH2-terminal sequence (V-S-P-P-F-I-K-Q-T-K-F-S-T-X-F-L-G-X-S-S) consists primarily of hydrophobic amino acid residues. Comparison of the amino acid composition and amino-terminal sequence of LTI with those of other known protease inhibitors reveals no significant similarity to other trypsin inhibitors. The novel physical characteristics suggest that LTI represents a new type of protease inhibitor.
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PMID:A novel trypsin inhibitor from the hemolymph of the horseshoe crab Limulus polyphemus. 198 74

Two fluorine-containing analogues of the cyclic AMP receptor protein (CRP) from Escherichia coli were prepared by biosynthetic incorporation of 5-fluorotryptophan (5-F-Trp) and 3-fluorotyrosine (3-F-Tyr). The 19F-n.m.r. spectrum of the [5-F-Trp]CRP showed two signals corresponding to the two tryptophan residues, and that of the [3-F-Tyr]CRP showed six signals (two overlapping) corresponding to the six tyrosine residues: these results are as expected for a symmetrical dimer. A comparison of the 19F-n.m.r. spectra of the CRP analogues in the presence and in the absence of cyclic AMP reveals that the chemical shifts of both tryptophan residues and of two of the six tyrosine residues show differences. Since none of these residues is in direct contact with the bound nucleotide (although Trp-85 is fairly close), these shift changes must arise from induced conformational effects. The 19F-n.m.r. spectra of complexes with cyclic GMP showed chemical-shift perturbations different from those caused by cyclic AMP, indicating that different conformational changes are induced by the binding of cyclic GMP. The 19F-n.m.r. spectrum of the complex of [3-F-Tyr]CRP with tubercidin 3',5'-(cyclic)monophosphate (which can activate transcription) showed essentially the same chemical-shift changes as seen for the cyclic AMP complex, indicating that similar conformational changes have been induced by the nucleotide binding. [3-F-Tyr]CRP in the presence of an equimolar amount of the 20 bp self-complementary DNA oligomer 5'-AATGTGAGTTAACTCACATT-3' and excess cyclic AMP gave an 19F-n.m.r. spectrum that was almost identical with that for the [3-F-Tyr]CRP-cyclic AMP complex, indicating that the binding of DNA does not induce significant conformational changes involving the tyrosine residues. Proteolysis of [3-F-Tyr]CRP with chymotrypsin produced a 31 kDa fragment that is a dimer containing the cyclic AMP-binding domain. This fragment contains five of the six tyrosine residues, and its 19F-n.m.r. chemical shifts were essentially the same as those of the intact protein except for one missing signal (signal F): this signal could be assigned to Tyr-206 and shown to be unperturbed by the binding of cyclic nucleotide to the intact [3-F-Tyr]CRP. The similarity of the 19F-n.m.r. chemical shifts in the alpha-fragment and the intact CRP indicates that the alpha-fragment retains the same structure as found in the intact protein.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:19F-n.m.r. studies of ligand binding to 5-fluorotryptophan- and 3-fluorotyrosine-containing cyclic AMP receptor protein from Escherichia coli. 215

The inactivation of tetrameric isocitrate lyase from Escherichia coli by 3-bromopyruvate, exhibiting saturation kinetics, is accompanied by the loss of one sulfhydryl per subunit. The substrates glyoxylate and isocitrate protect against inactivation whereas the substrate succinate does not. The modification by 3-bromopyruvate (equimolar to subunits) imparts striking resistance to digestion of isocitrate lyase by trypsin, chymotrypsin, and V8 protease as well as a major decrease in the intensity of tryptophan fluorescence. After alkylation, the sequence Gly-His-Met-Gly-Gly-Lys is found following the modified Cys residue in the tryptic peptide representing positions 196-201. Thus Cys195 is alkylated by 3-bromopyruvate.
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PMID:Alkylation of isocitrate lyase from Escherichia coli by 3-bromopyruvate. 218 22

The protein glia maturation factor beta, isolated from bovine brain, has been sequenced by automated Edman degradation and tandem mass spectrometry of overlapped peptide fragments generated by cyanogen bromide cleavage and enzymatic digestion with trypsin, chymotrypsin, and endoproteinases Asp-N and Lys-C. The protein has 141 amino acid residues and possesses no potential N-glycosylation sites. It contains three cysteines (at positions 7, 86, and 95), three methionines (at positions 33, 101, and 102), and one tryptophan (at position 132). The blocked amino terminus as determined by tandem mass spectrometry is an N-acetylated serine. The carboxyl terminus is a histidine. To our knowledge, the sequence shows no significant homology with other sequenced proteins. The molecular weight calculated from the sequence information is 16,582.
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PMID:Complete amino acid sequence of bovine glia maturation factor beta. 219 64

A serine proteinase (Alp) from the culture supernate of a clinical isolate of Aspergillus fumigatus was purified to virtual homogeneity at a yield of 41%. The procedure involved affinity chromatography on agarose-epsilon-amino-caproyl-D-tryptophan methyl ester. Alp had an estimated mol. wt of 32 Kda and the pI was determined at pH 7.9. The enzyme was fully inhibited by phenylmethyl sulphonyl fluoride, chymostatin and alpha-1-proteinase inhibitor, and it was largely inhibited by alpha-1-anti-chymotrypsin. Partial inhibition was observed with tosyl-phenylalanine chloromethyl ketone, but tosyl-lysine chloromethyl ketone was ineffective. Thus, Alp may be identical with the major chymotryptic activity of A. fumigatus, which has already been described. The N-terminal sequence of 25 amino acids revealed an 88% homology of Alp with the subtilisin-related proteinase of A. oryzae. Alp acted on casein over a broad range from pH 5.5 to 11.5 and also acts to a lesser extent on haemoglobin and serum albumin. The enzyme degraded elastin and a synthetic elastase substrate; hence, it may be identical with the previously described elastinolytic activity of the fungus. At pH 7.3 and a concentration of 1 microgram/ml, Alp was not toxic for Vero cells, but it efficiently detached such cells from a plastic surface. Specific antibodies against Alp were detected by enzyme immunoassay in the sera of patients and Alp-antigen was demonstrated by immunofluorescence in mycotic human lung. In addition, a second proteinase (Exalp) with extremely alkaline activity, and an aspartic proteinase of A. fumigatus are described.
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PMID:Purification and characterisation of an extracellular serine proteinase from Aspergillus fumigatus and its detection in tissue. 225 12

Data on alpha-chymotrypsin interactions with hydrophobic low-molecular compounds have been generalized. Existence of two sites of noncovalent interaction with hydrophobic nuclei of a ligand molecule is shown. When the substance to be bound contains only one hydrophobic nucleus, the interaction is mediated by a "hydrophobic pocket" of the enzyme--a binding site of amino acid residues which are, in the P1-position relative to the cleaved bond. Under these conditions substances with an asymmetric hydrophobic nucleus (of the tryptophan type) are better ligands for binding. In case of compounds containing several hydrophobic groups scattered in the space, interaction with the enzyme proceeds in two binding sites. New data are presented on the ligand specificity for binding sites of chymotrypsin in lower vertebrates. Relative position of hydrophobic groups of the ligand is shown as that of great importance for interaction with the enzyme. It is concluded that the binding sites of trypsin- and chymotrypsin-like proteinases of the lower vertebrates differ but less from each other as compared to binding sites of trypsin and chymotrypsin in mammals.
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PMID:[Hydrophobic interaction of alpha-chymotrypsin with low molecular weight compounds]. 227 Jun 21

Trp repressor of Escherichia coli K-12 is a dimeric protein (monomer size, 108 amino acids) that acquires high affinity for certain operator targets in double-stranded DNA upon interaction with L-tryptophan. High titer antiserum directed against E. coli Trp repressor protein, elicited in rabbits, was monospecific toward native or denatured Trp repressor. Using an enzyme-linked immunosorbent assay to measure antigen-antibody reaction, we found that the binding of L-tryptophan to Trp repressor was associated with a marked decrease in antibody reactivity that presumably accompanied a conformational change in this protein to a state with strong affinity for trp operator-bearing DNA. We analyzed the pattern of cleavage of Trp repressor by chymotrypsin and trypsin and the effect of L-tryptophan on such hydrolytic cleavages. Chymotrypsin cleaved Trp repressor mainly between residues 71 and 72. In the presence of L-tryptophan this cleavage was slowed. The first-order rate constants for chymotryptic digestion of Trp repressor were 7.6 X 10(-2) and 4.6 X 10(-2) min-1 in the absence and presence of L-tryptophan, respectively. Tryptic digestion was more complex. Initial cleavage of Trp repressor occurred with approximately equal facility between residues 69-70 or 84-85. Subsequent tryptic hydrolyses led eventually to a major core fragment containing the first 54 amino acids of Trp repressor plus four other fragments from the carboxyl-terminal half of the protein. In the presence of L-tryptophan, cleavage by trypsin between residues 54-55 and 84-85 was retarded, even when a previous hydrolytic event elsewhere in the protein had occurred. Tryptophan had essentially no effect on the tryptic hydrolysis of peptide bond 97-98, but accelerated cleavage at peptide bond 69-70. The first-order rate constants for the first tryptic cleavage of Trp receptor were 1.55 X 10(-1) and 1.33 X 10(-1) min-1 in the absence and presence of ligand, respectively. Our results are compatible with a structural model wherein certain amino acid side chains and peptide bonds of Trp repressor (specifically, those of residues 69-85) lie on or near the surface of the protein. This region of Trp repressor has been predicted to contain the operator recognition site. The susceptibility to proteolytic attack of at least four peptide bonds in this area changes when the protein interacts with L-tryptophan.
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PMID:Ligand-mediated conformational changes in Trp repressor protein of Escherichia coli probed through limited proteolysis and the use of specific antibodies. 241 31

The effects of various amino acids and phosphorylated forms of glucose on the release of digestive enzymes from particulate cellular pools, particularly zymogen granules, were evaluated in rat pancreas. Whole tissue homogenates, as well as zymogen granules isolated either by differential centrifugation in 0.3 M sucrose or by preparation in buffered sucrose and subsequent centrifugation in a Percoll gradient, were studied. The basic amino acids L-arginine and L-lysine, sites of tryptic cleavage, caused the release of trypsinogen, but not chymotrypsinogen, whereas the aromatic amino acids L-phenylalanine and L-tryptophan, sites of chymotryptic cleavage, caused release of both trypsinogen and chymotrypsinogen. Neither led to the release of the starch-splitting enzyme amylase. All effects occurred within the range of normal plasma concentrations for these amino acids in the rat. Two amino acids, L-threonine and hydroxy-L-proline, that are not sites of cleavage by trypsin or chymotrypsin, and a nonmammalian amino acid, aminoadipic acid, did not lead to release of trypsinogen, chymotrypsinogen, or amylase. Two phosphorylated forms of glucose, glucose 1-phosphate and glucose 1,6-diphosphate, caused the release of amylase, but of neither trypsinogen nor chymotrypsinogen. Contrary to previous results, D-glucose was without effect, as was glucose 6-phosphate. We propose that certain digestive end products, by direct action on zymogen granules, cause the selective release of the enzymes involved in their evolution from polymeric substrates during digestion.
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PMID:Digestive end products release pancreatic enzymes from particulate cellular pools, particularly zymogen granules. 242 Mar 68


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