Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.5.1.4 (deaminase)
 5,113 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The substrate specificity of carboxypeptidase (F-II) purified from watermelon for various synthetic peptides and esters was examined kinetically. The enzyme showed a broad substrate specificity against various carbobenzoxy- and benzyl-dipeptides. Peptides containing glycine or proline were hydrolyzed slowly by the enzyme. Peptides containing hydrophobic amino acids were hydrolyzed rapidly. The presence of hydrophobic amino acid residues, not only at the C-terminal position but also at the second position and probably the third position from the C-terminal resulted in an increase in the rate of hydrolysis. Inhibition studies with diisopropyl flurophosphate and diastereomers of carbobenzoxy-Phe-Ala demonstrated that the peptidase and esterase activities of the enzyme are both catalyzed by the same site of the enzyme molecule, but the binding sites for peptides and esters seem not to be the same. The enzyme also had amidase activity, which was optimal at pH 7.0.
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PMID:Substrate specificity of carboxypeptidase from Watermelon. 0 3

The specificity of bovine spleen cathepsin B2 has been investigated by means of some natural oligo- and polypeptides, i.e. glucagon, melittin, insulin A and B chain, bradykinin, angiotensin I and II, oxytocin ACTH, clupein and salmin. The enzyme is primarily a carboxypeptidase which hydrolyzes peptide linkages of most amino acids common to proteins. In addition, cathepsin B2 displays amidase and esterase activity without requiring a free carboxyl group. The main pH optimum is between 4 and 5, in some cases higher.
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PMID:On the specificity of bovine spleen cathepsin B2. 1 11

Two DFP-sensitive alkaline proteinases with strong esterase activity toward Ac-(Ala)3-OMe, designated as alkaline serine proteinases D and E, were purified pronase, a protease mixture from St. griseus K-1. Each was shown to be homogeneous by acrylamide disc gel electrophoresis. The molecular weights of these enzymes were estimated to be about 27,000 be gel filtration. Studies on their actions on acyl-tl-amino acid methyl or ethyl esters indicated that proteinases D and E both exhibited a broad substrate specificity and hydrolyzed the ester bonds of esters containing Trp, Tyr, Phe, Leu, and Ala. The esterase activities of both enzymes toward Ac-(Ala)3-OMe were the highest among proteinases so far isolated from various sources. Proteinases D and E also lacked cystine residues in their molecules, being entirely different from alkaline serine proteinases A, B, and C in pronase. Some differences were , however, observed between them as regards pH stability, behavior on CM-cellulose, mobility on polyacrylamide electrophoresis, and amidase activity toward Suc-(Ala)3-pNA.
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PMID:Alkaline serine proteinases D and E of Streptomyces griseus K-1. 1 70

Hamsters were exposed to 30 ppm nitrogen dioxide (NO2) for 2 and 50 days and sacrificed. Pulmonary lavage was carried out on a portion of each group to obtain an alveolar macrophage fraction. Proteolytic activity (P.A.), as measured by caseinolysis at pH 3.0 and pH 5.0, increased nearly twofold in the 2-day NO2 lung extracts and fourfold in the 50-day NO2 samples. P.A. in macrophage extract at pH 3.0 increased tenfold with both 2- and 50-day NO2 exposure. Lung extract hydrolysis of specific esterase and amidase substrates and susceptibility to activators and inhibitors of proteolytic enzymes are consistent with the presence of lysosomal cathepsin A, B1, B2, C, D, and E. The lack of NO2-induced increases in P.A. at physiologic values of pH may be the basis of the lack of significant pulmonary tissue destruction observed in rodents exposed to NO2 for 2 and 50 days.
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PMID:Nitrogen dioxide and pulmonary proteolytic enzymes. Effect on lung tissue and macrophages. 1 98

Cathepsin A [EC 3.4.2.-] of small molecular size (cathepsin A, S) has been purified about 800-fold from pig kidney by procedures including chromatographies on DEAE-Sephadex, SP-Sephadex, and Sephadex G-150. 1. The homogeneity of the purified enzyme was proved by ultracentrifugation and polyacrylamide gel electrophoresis. The molecular weight (100,000) and isoelectric point (pI=5.0) were estimated. 2. The enzyme was remarkably stabilized by sucrose and KCl, and was most stable at pH 5-5.5 in the presence of both stabilizers. The enzyme had not only peptidase activity but also esterase and amidase activity; it was optimally active at pH 5.2 for peptide hydrolysis and at pH 8 for the hydrolysis of esters and amides. 3. Diisopropyl fluorophosphate and iodoacetamide completely inhibited these three activities. 4. The enzyme hydrolyzed various benzoyl- and benzyloxycarbonyl-dipeptides with neutral, acidic, and basic amino acids, and proline in the C-terminal position. The carboxypeptidase nature of the enzyme was proved by its action on an oligopeptide. 5. Several enzymatic properties of cathepsin A, S were almost the same as thoas of cathepsin A of large molecular size (cathepsin A, L) and the crude homogenate.
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PMID:Purification and some properties of cathepsin A of small molecular size from pig kidney. 23 65

We have previously demonstrated the existence of two types of endopeptidase in Escherichia coli. A purification procedure is described for one of these, designated protease II. It has been purified about 13,500-fold with a recovery of 24%. The isolated enzyme appears homogeneous by electrophoresis and gel filtration. Its molecular weight is estimated by three different methods to be about 58,000. Its optimal pH is around 8. Protease II activity is unaffected by chelating agents and sulfhydryl reagents. Amidase and proteolytic activities are stimulated by calcium ion, which decreases the enzyme stability. Like pancreatic trypsin, this endopeptidase catalyses the hydrolysis of alpha-amino-substituted lysine and arginine esters. It appears distinct from the previously isolated protease I, which is a chymotrypsin-like enzyme. The apparent Michaelis constant for hydrolysis of N-benzoyl-L-arginine ethyl ester is 4.7 X 10(-4) M. The esterase activity is inhibited by diisopryopylphosphorofluoridate (Ki(app) equals 2.7 X 10(-3) M) and tosyl lysine chloromethyl ketone (Ki(app) equals 1.8 X 10(-5) M), indicating that serine and histidine residues may be present in the active site. However, protease II is insensitive to phenylmethanesulfonyl fluoride and several natural trypsin inhibitors. Its amidase and esterase activities are competitively inhibited by free arginine and aromatic amidines. The proteolytic activity measured on axocasein is very low. In contrast to trypsin, protease II is without effect on native beta-galactosidase. It easily degrades aspartokinase I and III. Nevertheless both enzymes are resistant to proteolysis in the presence of their respective allosteric effectors. These results provide further evidence that such differences in protease susceptibility can be related to the conformational state of the substrate. The possible implication of structural changes in the mechanism of preferential proteolysis in vivo, is discussed.
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PMID:Protease II from Escherichia coli. Purification and characterization. 24 Aug 39

Radioactive alpha factor is degraded to discrete biologically inactive fragments by the target a cells of S. cerevisiae, but not by alpha cells which make the pheromone. The pattern of cleavage products and sequence analysis of one fragment indicated that the first scission occurred between leucine 6 and lysine 7. The protease inhibitors tosyl-L-argininyl-methyl ester (TAME), tosyl-L-lysyl-chloromethylketone (TLCK) and N-acetyl-L-leucyl-L-leucyl-L-argininal (leupeptin) markedly prolonged the period of G1 arrest in a cells exposed to alpha factor, while other standard protease inhibitors had little or no effect. The presence of TAME and leupeptin, or TLCK, reduced the rate of degradation of radioactively labeled alpha factor by a cells. Intact yeast cells have apparent esterase and amidase activities that are blocked by the same spectrum of inhibitors that potentiate alpha factor action. Purified alpha factor is a competitive inhibitor of these hydrolytic activities. The activities are present in yeast mutants which have greatly reduced levels of the three major vacuole-associated proteases (A, B and C) or which carry an ochre mutation in the major neutral protease (B). These observations indicate that the inactivation of alpha factor is due to endoproteolytic cleavage, the destruction of the pheromone is required to overcome its effects on growth and that degradation of the molecule may involve surface bound endopeptidase(s).
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PMID:Recovery of S. cerevisiae a cells from G1 arrest by alpha factor pheromone requires endopeptidase action. 39

The molecular weights of purified calotropain-FI and FII were determined by sodium dodecyl sulphate-polyacrylamide gel electrophoresis and by filtration of Sephadex G-100. Activation of calotropain-FI and FII by different sulfhydryl activators was studied. The results obtained from inhibition studies by various enzyme-modifying reagents suggest the possible role of cysteine and histidine residues in the active site of both the enzymes. The free and total sulfhydryl contents of both the enzymes were determined by the use of 5-5'-dithio-bis-2-nitrobenzoic acid. Total amino acid compositions of both the enzymes were also determined. A comparative study of the esterase, amidase, milk-clotting and caseinolytic activities of calotropain-FI and FII are also presented.
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PMID:Studies on proteinases from Calotropis gigantea latex. II. Physico-chemichal properties of calotropain-FI and FII. 44 38

A physical model approach to the topical delivery of a vidarabine ester prodrug was investigated. It involved modeling, theoretical simulations, experimental method development for factoring and quantifying parameters, and, finally, employment of the deduced parameters to determine the steady-state species fluxes and concentration profiles in the target tissue. The present report describes the physical modeling and theoretical simulation aspects. The physical model for the simultaneous transport and bioconversion of a topically delivered prodrug was formulated assuming homogeneous enzyme distributions and constant diffusivities in the membrane. The mathematical problem was solved, and the solution yielded concentration profiles and fluxes of all species in the biomembrane. These results provided the prevailing levels of the prodrug, the drug, and the metabolite at the target site and the transport rates of all species into the bloodstream. Computations of concentration profiles and fluxes were carried out for a reasonable range of the parameters. The relative activities of the esterase and the deaminase enzymes, as well as the stratum corneum permeabilities, were important in influencing the concentration profiles and fluxes of all species.
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PMID:Physical model evaluation of topical prodrug delivery-simultaneous transport and bioconversion of vidarabine-5'-valerate I: Physical model development. 51 80

Results of initial studies on methods for determining various model parameters are reported. By employing excised hairless mouse skin in a diffusion cell system, numerous model parameter values were deduced. The stratum corneum permeability was estimated from steadystate fluxes with preparations of heat-separated epidermal membranes. Determinations of dermis diffusivities and enzyme rate constants in situ involved considering the simultaneous transport and the enzyme processes and factoring the diffusivities and enzyme rate constants from the overall kinetics. Dermal diffusivities were on the order of 10-6 cm2/sec for vidarabine and its 5'-valerate ester. The enzyme rate constants were 1.70 x 10-3 sec-1 for the esterase and 8.68 x 10-3 sec-1 for the deaminase.
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PMID:Physical model evaluation of topical prodrug delivery-simultaneous transport and bioconversion of vidarabine-5'-valerate II: Parameter determinations. 51 81


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