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

---

Query: EC:3.4.21.1 (chymotrypsin)
10,938 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Two proteinases (2A and 2B) purified from the granular fraction of horse blood leucocytes degrade casein (Km values 12.8 and 6mg/ml respectively) with maximum activity at pH 7.4 and in the presence of 2m-urea. Urea-denatured haemoglobin, fibrinogen, albumin and resorcin/fuchsin-stained elastin are digested at a slower rate. The enzymes hydrolyse synthetic substrates of elastase, N-benzyloxycarbonyl-L-alanine 4-nitrophenyl ester (Km 0.114 and 0.178 mM) and N-acetyl-tri-L-alanine methyl ester (Km 5.55 and 0.98 mM), but they do not hydrolyse synthetic substrates of trypsin, chymotrypsin and thrombin. The examined proteinases are completely inhibited by 2 mM-di-isopropyl phosphorfluoridate and show a sensitivity to butyl and octyl isocyanates similar to that of pancreatic elastase. The pH-dependence of their photoinactivation in the presence of Rose Bengal indicates the presence of histidine in the active centre. Proteinase 2A rather insensitive to iodination by IC1 as is pancreatic elastase, whereas proteinase 2B is totally inactivated after incorporation of five iodine atoms per enzyme molecule.
...
PMID:Substrate specificity and modifications of the active centre of elastase-like neutral proteinases from horse blood leucocytes. 0 9

1. alpha 1-Proteinase inhibitor was isolated from human plasma by a five-step procedure. Isoelectric focusing showed that six components focused between pH4.85 and 4.95. 2. The mol.wt. of the inhibitor was 52000 by sedimentation equilibrium and sodium dodecyl sulphate/polyacrylamide-gel electrophoresis. The amino acid and carbohydrate compositions of the inhibitor were also determined. 3. The far-u.v.c.d. (circular-dichroism) spectrum indicated that the inhibitor had about 36% alpha-helical content. 4. The loss of proteinase-inhibitory activity when the inhibitor was exposed to pH values less than 5.0 or greater than 10.5 was accompanied by small changes in the far-u.v.c.d. spectrum and large changes in the near-u.v.c.d. spectrum. The change at alkaline pH was associated with ionization of tyrosine residues. 5. Interaction of inhibitor with chymotrypsin caused perturbation of the c.d. spectrum and this was used to follow the interaction and show a 1:1 stoicheiometry. 6. C.d., electrophoresis and isoelectric focusing showed that the inhibitor-enzyme complex is degraded by free enzyme. 7. Parallel studies with trypsin indicated that it too forms a 1:1 complex with inhibitor and is degraded by excess of enzyme.
...
PMID:Isolation and characterization of human plasma alpha 1-proteinase inhibitor and a conformational study of its interaction with proteinases. 0 69

Proteinase A from yeast causes a stepwise degradation of yeast phosphofructokinase, resembling the action of subtilisin on this enzyme. Proteinase B, however, exhibits a limited proteolysis similar to the action of alpha-chymotrypsin.
...
PMID:Differences in the degradation of yeast phosphofructokinase by proteinases A and B from yeast. 13 76

Two proteinases (proteinases I and II) have been purified from Crotalus adamanteus venom to the stage of electrophoretic homogeneity and proteinase II has been crystallized. The proteinase differ slightly in molecular weight and amino acid composition. Both are metalloenzymes requiring Zn2+ or Ca2+, or both; neither requires thiol compounds for activation. The proteinases are free of esterolytic activity against benzoly-L-arginine ethyl ester and benzoyl--tyrosine ethyl ester. Proteinase II cleaves the oxidized B chain of insulin at the bonds Phe1-Val2, His5-Leu6, His10-Leu11, Ala14-Leu15, Leu15-Tyr16, and Tyr-16-Leu17. Digestion of polylsine and polyarginine by proteinase II liberates products ranging from dodecapeptides to hexapeptides. Proteinases I and II catalytically inactive human plasma alpha 1-proteinase inhibitor (54,000 daltons). Electrophoretic analysis of the reaction of proteinase II with alpha 1-proteinase inhibitor reveals that an inactivated inhibitor species of 50,000 daltons is formed, and a peptide of 4,000 daltons is released. The gradual disappearance of the native inhibitor results in the corresponding loss of inhibitory activity against trypsin and chymotrypsin.
...
PMID:Purification and some properties of two proteinases from Crotalus adamanteus venom that inactivate human alpha 1-proteinase inhibitor. 30 70

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.
...
PMID:Peptidyl transfer ribonucleic acid hydrolase activity of proteinase k. 38 46

Proteinase inhibitor II, an inhibitor of chymotrypsin and trypsin, is a heat-stable protein with a dimeric molecular weight of 21 000 that is a component of Russet Burbank potato tubers. Four monomeric isoinhibitor species of molecular weight 10 500 comprise inhibitor II and were isolated by chromatography on phosphocellulose in 8 M urea. Upon removal of the urea, each monomeric species dimerized to yield homogeneous dimers. The three major protomer species, called B, C, and D, and their homogeneous dimers were further characterized. They have similar molecular weights and amino acid compositions, and each has an N-terminal alanine residue. Dimers of purified protomers B, C, and D exhibited full cross-reactivities with each other in immunological double-diffusion assays. Reconstituted dimers possess two binding sites for bovine alpha-chymotrypsin, indicating that each monomer possesses one binding site for this enzyme. Significant differences were noted among the reconstituted dimers in their isoelectric points, immunoelectrophoretic mobilities, ion-exchange properties, and their inhibitory reactivities against trypsin. The properties of the inhibitor II dimeric species are similar but not identical to inhibitors IIa and IIb reported from Japanese potatoes (variety "Danshaku-Imo"), indicating the existence of intervarietal, as well as intravarietal, differences among potato tuber inhibitor II isoinhibitors.
...
PMID:Proteinase inhibitor II from potatoes: isolation and characterization of its protomer components. 82 19

Proteinase inhibitors were isolated from Scopolia japonica cultured cells. Isolation procedures involve concentration by a hydrophobic resin of Diaion HP-20, decolorization by Duolite A-7, affinity chromatography on trypsin-Sepharose, and Bio-Gel P-4 chromatography. It was found that the proteinase inhibitors from S. japonica cells are a mixture of at least five components. For the inhibitory components except one, amino acid analyses, measurements of sedimentation equilibrium and optical rotatory dispersion (ORD) were carried out. The inhibitors were shown to be the polypeptides with molecular weights in the range of approximately 4000 to 6000. In addition, one of them was found to have approximately 15% alpha-helical conformation by the Moffitt-Yang analysis of ORD data. The inhibitors were found to have potent inhibitory activity for trypsin, chymotrypsin, plasmin, kallikrein and pepsin but not for papain with synthetic and natural substrates. These inhibitors formed stable complexes with trypsin and chymotrypsin in an equimolar ratio, and their inhibitory mechanisms for both enzymes were of non-competitive type.
...
PMID:Broad-specificity proteinase inhibitors in Scopolia japonica (Solanaceae) cultured cells. Isolation, physicochemical properties, and inhibition kinetics. 117 2

Proteinase binding by pregnancy zone protein (PZP), an alpha-macroglobulin involves bait region cleavages, association of dimeric-PZP into tetrameric and reaction of internal gamma-glutamyl-beta-cysteinyl thiol esters of PZP with proteinase side chains. The product is an equimolar enzyme-PZP(tetramer) covalently linked complex with four free sulfhydryl groups. The kinetics of the appearances of sulfhydryl groups during the reaction of PZP with chymotrypsin has been investigated using stopped-flow and conventional mixing techniques over a broad concentration range. Thiol ester cleavages followed double exponential decays corresponding with two steps. The faster one resulted in the appearance of three sulfhydryl groups with an observed rate constant, k(obs) = k1.1 + k1.2 delta E, dependent on the excess concentration of chymotrypsin, delta E, and k1.1 = 0.03 s-1 and k1.2 = 4 x 10(4) M-1 s-1. The last sulfhydryl group appeared in a slower step, with similar concentration dependence and k2.1 approximately 0.003 s-1 and k2.2 approximately 5 x 10(3) M-1s-1. Covalent binding of the enzyme apparently was simultaneous with the faster thiol ester cleavage step. Based on these and previous results a model of the reaction mechanism of the proteinase binding reaction of PZP is proposed. It consists of four major steps: (i) Bait region cleavage of PZP-dimers by the enzyme, (ii) fast association of enzyme-PZP(dimer) species with native PZP or with another enzyme-PZP(dimer) compound resulting in release of one of the associated enzyme molecules (iii) reaction of an average of three thiol esters of the enzyme-PZP(tetramer) intermediate with the associated internal enzyme molecule or with an external one. In this step one enzyme molecule becomes covalently linked to the PZP-(tetramer), three sulfhydryl groups appear and the enzymic activity of the bound enzyme molecule decreases to the level of that of the final complex. (iv) Hydrolysis of the last thiol ester and in the presence of excess enzyme, degradation of enzyme-PZP(tetramer) complexes and formation of fragments some of which are the size of PZP(dimer) with enzyme bound.
...
PMID:Kinetics and mechanism of proteinase-binding of pregnancy zone protein (PZP). Appearance of sulfhydryl groups in reactions with proteinases. 128 48

We previously found a trypsin-like proteinase which momentarily appears immediately before DNA synthesis in the cell cycle of Escherichia coli synchronized by phosphate starvation and which is closely related to the initiation of DNA replication (Kato, M., Irisawa, T., Morimoto, Y. and Muramatu, M., unpublished results). The proteinase was named proteinase In. It was purified approximately 2880-fold with a recovery of 15%. The isolated enzyme appeared homogeneous by gel filtration and electrophoresis. Its molecular mass was estimated by analytical gel filtration and SDS/PAGE as approximately 66 kDa. The isoelectric point of proteinase In is 4.9 and its optimal pH is approximately 9. Although protein In hydrolyzes fluorogenic substrate for trypsin, its hydrolytic activity seems markedly affected by amino-acid sequence lying towards the N-terminal from the P1 (lysine, arginine) residue. The proteinase does not hydrolyze N2-benzoyl-D,L-arginine-4-nitronanilide and fluorogenic substrates for chymotrypsin and elastase. The proteinase activity is inhibited by leupeptin, antipain and 4-nitrophenyl 4-guanidinobenzoate, but the effects of tosyl-L-lysine chloromethane, diisopropylfluorophosphate, benzamidine and pentamidine isethionate on the proteinase activity are weak or not inhibitory. Its activity is strongly affected in the presence of NaCl and KCl, and at a concentration of 1.5 M, these increase the activity 14-fold and 13-fold, respectively, above that without salt. Proteinase In was strongly inhibited by various esters of trans-4-guanidinomethylcyclohexanecarboxylic acid, and their inhibitory effects were roughly correlated with those on growth of E. coli. Proteinase activity was found in the cytoplasmic fraction.
...
PMID:Purification and characterization of proteinase In, a trypsin-like proteinase, in Escherichia coli. 133 54

A proteinase was purified to electrophoretic homogeneity from crude extracts of the thermoacidophilic archaebacterium Sulfolobus solfataricus. Molecular mass values assessed by SDS-PAGE and gel filtration were 54 and 118 kDa, respectively, which points to a dimeric structure of the molecule. An isoelectric point of 5.6 was also determined. The enzyme behaved as a chymotrypsin-like serine proteinase, as shown by the inhibitory effects exerted by phenylmethanesulfonyl fluoride, 3,4-dichloroisocoumarin, tosylphenylalaninechloromethyl ketone and chymostatin. Consistently with the inhibition pattern, the enzyme cleaved chromogenic substrates at the carboxyl side of aromatic or bulky aliphatic amino acids; however, it effectively attacked only a small number of such substrates, thus, displaying a specificity much narrower than and clearly different from that of chymotrypsin. This was confirmed by its inability to digest a set of natural substrate proteins, as well as insulin chains A and B; only after alkylation casein was degraded to some extent. Proteinase activity was significantly stimulated by Mn2+ which acted as a mixed-type nonessential activator. The enzyme also displayed a broad pH optimum in the range 6.5-8.0. Furthermore, it was completely stable up to 90 degrees C; above this temperature it underwent first-order thermal inactivation with half-lives ranging from 342 min (92 degrees C) to 7 min (101 degrees C). At 50 degrees C it could withstand 6 M urea and, to some extent, different organic solvents; however, at 95 degrees C it was extensively inactivated by all of these compounds. None of the chemical physical properties of the enzyme, including amino-acid analysis, provided evidence of a possible relation to other well-known microbial serine proteinases.
...
PMID:A heat-stable serine proteinase from the extreme thermophilic archaebacterium Sulfolobus solfataricus. 150 89


1 2 3 4 5 6 Next >>

---