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 major outer membrane proteins from 10 gonococcal strains were examined after 125I-labeling of the proteins as single bands resolved by polyacrylamide gel electrophoresis in sodium dodecyl sulfate. These 125I-proteins were then treated with either trypsin or alpha-chymotrypsin, and the resultant 125I-peptides were visualized by autoradiography after two-dimensional electrophoretic and chromatographic separation on thin-layer cellulose sheets. Several 125I-peptides were present in all the major outer membrane proteins examined. The presence and absence of additional 125I-peptides segregated the major proteins into two pattern groups. One group consisted of major outer membranes with molecular weights of 34,000 or 33,000; major proteins with molecular weights of 32,000 constituted the other group. Two beta-lactamase-producing gonococcal isolates were examined. Their major outer membrane proteins were identical in apparent molecular weights and alpha-chymotryptic 125I-peptide fingerprints; these proteins contained 125I-peptides not found in other gonococcal major proteins. No 125I-peptide differences were found among the major outer membrane proteins of strain F62 gonococci that exhibited differences in piliation and/or colony opacity characteristics.
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PMID:Studies on gonococcus infection. XVIII. 125I-labeled peptide mapping of the major protein of the gonococcal cell wall outer membrane. 11 Jun 81

Protoplasis of Bacillus licheniformis 749/C (a mutant constitutive for penicillinase production) continued to synthesize and release penicillinase in hypertonic growth medium in the presence of trypsin and chymotrypsin at 25 mug each per ml. When the protoplasts were stripped of about half of their membrane-bound penicillinase by pretreatment at pH 9.5 or with a higher level of trypsin, penicillinase activity no longer increased in the presence of the proteases. This effect was immediately eliminated after addition of soybean trypsin inhibitor. These proteases do not significantly inhibit general protein synthesis. Stripped protoplasts of strain 749/C and of uninduced strain 749 (unable to synthesize penicillinase) were incubated with 50 mug of chymotrypsin per ml, and the supernatent fluids were examined immunochemically for peptides derived from the penicillinase chain. Such fargments were found only with the protoplasts capable of synthesizing penicillinase (strain 749/C). The direct detection of the products of protease degradation of a susceptible form of penicillinase provides strong evidence that, in stripped protoplasts of B. licheniformis 749/C, penicillinase synthesis continues in the presence of trypsin or chymotrypsin and that, in these modified membranes, the protease is able to act on an early form of the enzyme that has not yet attained the protease-resistant conformation characteristic of the membrane-bound and exopenicillinases. This finding is discussed in terms of the current models of penicillinase secretion.
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PMID:Further evidence for a partially folded intermediate in penicillinase secretion by Bacillus licheniformis. 23 42

Isolated from an Escherichia coli strain MEN-1 is a plasmid-mediated beta-lactamase that confers resistance to methoxy imino third-generation cephalosporins. The protein purified to homogeneity was digested by trypsin, chymotrypsin and endoproteinase Asp-N. Amino acid sequence determinations of the resulting peptides gave rise to the alignment of the 263 residues of the beta-lactamase. From amino acid sequence comparison MEN-1 was found to share more than 72% identity with the chromosomally mediated beta-lactamases of Klebsiella oxytoca. Therefore, MEN-1 is the first transferable extended-spectrum beta-lactamase which is not directly derived from the widespread TEMs or SHV-1 penicillinases with which it presents less than 39% identity.
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PMID:Close amino acid sequence relationship between the new plasmid-mediated extended-spectrum beta-lactamase MEN-1 and chromosomally encoded enzymes of Klebsiella oxytoca. 163 93

The complete amino acid sequence of the p453-plasmid-mediated PIT-2 beta-lactamase (SHV-1) was determined. The protein contains 265 residues. Peptides resulting from digestions with trypsin, Staphylococcus aureus V8 proteinase, chymotrypsin and Lys-C proteinase and cleavage with CNBr were separated and purified by using reverse-phase h.p.l.c. The amino acid sequence of each peptide was manually determined with the dimethylaminoazobenzene isothiocyanate/phenyl isothiocyanate double-coupling method. The primary structure of PIT-2 beta-lactamase was compared with those of two closely related enzymes, namely TEM-1 beta-lactamase and the beta-lactamase of Klebsiella pneumoniae strain LEN-1. The PIT-2 beta-lactamase amino acid sequence was strongly retained, with respectively 68% and 88% homology. Thus PIT-2 enzyme could represent an evolutionary step between a chromosomally encoded beta-lactamase and the plasmid-mediated TEM beta-lactamases.
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PMID:Complete amino acid sequence of p453-plasmid-mediated PIT-2 beta-lactamase (SHV-1). 326 Apr 90

Phenylpropynal is a specific, irreversible, non-beta-lactam inhibitor of typical beta-lactamases. In the presence of millimolar concentrations of phenylpropynal, the beta-lactamase I of Bacillus cereus and the beta-lactamases of Staphylococcus aureus and Escherichia coli become completely inactivated; the beta-lactamase II of B. cereus is not affected. The E. coli beta-lactamase is considerably more sensitive to the reagent than the gram-positive enzymes. A variety of structural analogs of phenylpropynal are much less effective inhibitors. Bovine alpha-chymotrypsin, bovine carboxypeptidase A, and the D,D-carboxypeptidase/transpeptidase of Streptomyces R-61 were not inactivated by phenylpropynal. The inactivation of the E. coli beta-lactamase can be significantly retarded when the good substrate benzylpenicillin is also present. The development of a characteristic chromophore (lambda max 318 nm) during beta-lactamase inactivation suggests that covalent modification of the enxymes is involved; arginine and/or lysine modification is indicated.
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PMID:Phenylpropynal, a specific, irreversible, non-beta-lactam inhibitor of beta-lactamases. 676 45

Proteus vulgaris RO104 strain produces a chromosomally encoded beta-lactamase that confers resistance to various beta-lactam antibiotics including methoxyimino third-generation cephalosporins. The beta-lactamase hydrolyzes first- and second-generation cephalosporins efficiently and cefotaxime to a lesser extent. Catalytic activity is inhibited by low concentrations of clavulanic acid and sulbactam. By its broad-spectrum substrate profile, beta-lactamase of Proteus vulgaris RO104 belongs to the group 2e defined by Bush. The protein purified to homogeneity by a four-step procedure was characterized by a pI of 8.31 and a specific activity of 1200 U/mg. The beta-lactamase was digested by trypsin, endoproteinase Asp-N and chymotrypsin. Amino-acid sequence determinations of the resulting peptides allowed the alignment of the 271 amino-acid residues of the protein which did not contain any cysteine residue. From amino-acid sequence comparisons, Proteus vulgaris RO104 beta-lactamase was found to share about 68% identity with the chromosomally mediated beta-lactamases of Klebsiella oxytoca D488 and E23004. Therefore, the cephalosporin-hydrolyzing beta-lactamase of Proteus vulgaris RO104 belongs to Ambler's class A.
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PMID:Chromosomally encoded cephalosporin-hydrolyzing beta-lactamase of Proteus vulgaris RO104 belongs to Ambler's class A. 804 7

Serratia fonticola CUV produces two isoenzymes (forms I and II) with beta-lactamase activity which were purified by a five-step procedure. The isoenzymes had identical kinetic parameters and isoelectric point (pI = 8.12). They were characterized by a specific activity towards benzylpenicillin of 1650 U/mg. The beta-lactamase hydrolyzed benzylpenicillin, amoxycillin, ureidopenicillins, first- and second-generation cephalosporins. Carboxypenicillins and isoxazolylpenicillins were hydrolyzed to a lesser extent. Towards cefotaxime and ceftriaxone (third-generation cephalosporins), the S. fonticola enzyme exhibited catalytic efficiencies much higher than those of MEN-1 and extended-spectrum TEM derivative beta-lactamases. The beta-lactamase from S. fonticola was markedly inhibited by beta-lactamase inhibitors such as clavulanic acid, sulbactam and tazobactam. The purified isoenzymes were digested by trypsin, endoproteinase Asp-N and chymotrypsin. Amino acid sequence determinations of the resulting peptides allowed the alignment of 267 amino acid residues (Swiss-Prot, accession number P 80545) for form I beta-lactamase. Form II is five residues shorter than form I at its N-terminus. From amino acid sequence comparisons, S. fonticola CUV beta-lactamase was found to share more than 69.3% identity with the chromosomally encoded beta-lactamases of Klebsiella oxytoca, Proteus vulgaris, Citrobacter diversus and the plasmid-mediated enzymes MEN-1 and Toho-1. Therefore, the oxyimino cephalosporin-hydrolyzing beta-lactamase of S. fonticola belongs to Ambler's class A. Contribution of the serine at ABL 237 in the broad-spectrum activity of these beta-lactamases is discussed.
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PMID:Characterization and amino acid sequence analysis of a new oxyimino cephalosporin-hydrolyzing class A beta-lactamase from Serratia fonticola CUV. 930 Aug 9

Serine beta-lactamases are inhibited by phosphonate monoester monoanions. These compounds phosphonylate the active site serine hydroxyl group to form inert, covalent complexes. Since spontaneous hydrolysis of these phosphonates is generally quite slow, the beta-lactamase active site must have considerable affinity for the (presumably) pentacoordinated phosphonyl transfer transition state. Structural analogs of such a transition state might well therefore be effective and novel beta-lactamase inhibitors. Complexes of vanadate with hydroxamic acids may be able to achieve such a structure. Indeed, mixtures of these two components, but neither one alone, were found to inhibit a typical class C beta-lactamase. A Job plot of the inhibition by vanadate/benzohydroxamic acid mixtures indicated that the inhibitor was a 1:1 complex for which an inhibition constant of 4.2 microM could be calculated. A bacterial DD-peptidase, structurally similar to the beta-lactamase, was also inhibited (K(i) = 22 microM) by this complex. A similar rationale would suggest that other serine hydrolases might also be inhibited by these mixtures. In fact, chymotrypsin was inhibited by a complex of vanadate with benzohydroxamic acid (K(i) = 10 microM) and elastase by a complex with acetohydroxamic acid (K(i) = 90 microM).
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PMID:Inhibition of serine amidohydrolases by complexes of vanadate with hydroxamic acids. 1092 45

Both functional and structural studies of serine beta-lactamases indicate the existence of an oxyanion hole at the active site with an important role in catalysis. The functional presence of the oxyanion hole is demonstrated by the previous observation that thiono-beta-lactams are very poor substrates of beta-lactamases (B. P. Murphy, and R. F. Pratt, 1988, Biochem. J. 256, 669-672) and in the present paper by the inability of these enzymes to catalyze hydrolysis of a thiono analog of a depsipeptide substrate. This thiono effect was first noted and interpreted in regard to classical serine hydrolases although the chemical basis for it has not been firmly established either in those enzymes or in beta-lactamases. In this paper a computational approach to a further understanding of the effect has been taken. The results for a class C beta-lactamase show that the deacylation tetrahedral intermediate interacted more strongly with the enzyme with an O(-) placed in the oxyanion hole than an S(-). On the other hand, the converse was true for acylation tetrahedral intermediate species, a result distinctly not in accord with experiment. These results indicate that the thiono effect does not arise from unfavorable interactions between enzyme and thiono substrate at the tetrahedral intermediate stage but must be purely kinetic in nature, i.e., arise in a transitional species at an early stage of the acylation reaction. The same conclusion as to the origin of the thiono effect was also indicated by a less extensive series of calculations on a class A beta-lactamase and on chymotrypsin.
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PMID:The Oxyanion Hole in Serine beta-Lactamase Catalysis: Interactions of Thiono Substrates with the Active Site. 1135 71

A series of specific alpha-ketoheterocycles (benzoxazole, thiazole, imidazole, tetrazole, and thiazole-4-carboxylate) has been synthesized in order to assess their potential as beta-lactamase inhibitors. The syntheses were achieved either by construction of the heterocycle (benzoxazole) from an appropriate alpha-hydroxyimidate, followed by oxidation of the alcohol, or by direct reaction of methyl phenaceturate with a lithiated heterocycle. The properties of these compounds in aqueous solution are described and their inhibitory activity against beta-lactamases assessed. They did inhibit the class C beta-lactamase of Enterobacter cloacae P99 but not the TEM beta-lactamase. The most effective inhibitor of the former enzyme (K(i)=0.11 mM) was 5-(phenylacetylglycyl) tetrazole, probably because it is an anion at neutral pH. Interpretation of the results was aided by computational models of the tetrahedral adducts. Most of the compounds also inhibited alpha-chymotrypsin but not porcine pancreatic elastase.
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PMID:Design, synthesis, and evaluation of alpha-ketoheterocycles as class C beta-lactamase inhibitors. 1150 40


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