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)

The substrate specificity of human pancreatic elastase 2 was investigated by using a series of peptide p-nitroanilides. The kinetic constants, kcat and Km, for the hydrolysis of these peptides revealed that this serine protease preferentially hydrolyzes peptides containing P1 amino acids which have medium to large hydrophobic side chains, except for those which are disubstituted on the first carbon of the side chain. Thus, human pancreatic elastase 2 appears to be similar in peptide bond specificity to the recently described porcine pancreatic elastase 2 [Gertler, A., Weiss, Y., & Burstein, Y. (1977) Biochemistry 16, 2709] but differs significantly in specificity from porcine elastase 1. The best substrates for human pancreatic elastase 2 were glutaryl-Ala-Ala-Pro-Leu-p nitroanilide and succinyl-Ala-Ala-Pro-Met-p-nitroanilide. However, there was little difference among substrates with leucine, methionine, phenylalanine, tyrosine, norvaline, or norleucine in the P1 position. Changes in the hydrolysis rate of peptides with differing P5 residues indicate that this enzyme has an extended binding site which interacts with at least five residues of peptide substrates. The overall catalytic efficiency of human pancreatic elastase 2 is significantly lower than that of porcine elastase 1 or bovine chymotrypsin with the compounds studied.
...
PMID:Substrate specificity of human pancreatic elastase 2. 689 42

A number of N-arylbenzisothiazolinone 1,1-dioxides have been synthesized and examined for inhibitory activity against human leukocyte and porcine pancreatic elastase (EC 3.4.21.11), bovine alpha-chymotrypsin (EC 2.4.21.1), human leukocyte cathepsin G (EC 3.4.21.20), and bovine trypsin (EC 3.4.21.4). They are potent, selective, competitive inhibitors of human leukocyte elastase and chymotrypsin. The inhibitory capacity of these compounds is directly related to the electron-withdrawing capability of the aryl substituents. When sufficiently activated, the amide bond in the heterocyclic ring can be cleaved by the enzyme, resulting in inhibition which is highly specific. The most potent inhibitor of hummotrypsin. The inhibitory capacity of these compounds is directly related to the electron-withdrawing capability of the aryl substituents. When sufficiently activated, the amide bond in the heterocyclic ring can be cleaved by the enzyme, resulting in inhibition which is highly specific. The most potent inhibitor of human leukocyte elastase, the 2,4-dinitrophenyl derivative, has a Ki of 2.16 microM with elastase and 0.77 microM with chymotrypsin. This study demonstrates that it is possible to design specificity into non-peptide, low molecular weight serine protease inhibitors, which may have considerable pharmacologic potential.
...
PMID:Selective inhibition of human leukocyte elastase and bovine alpha-chymotrypsin by novel heterocycles. 691 80

A cDNA library prepared from human liver has been screened for factor IX (Christmas factor), a clotting factor that participates in the middle phase of blood coagulation. The library was screened with a single-stranded DNA prepared from enriched mRNA for baboon factor IX and a synthetic oligonucleotide mixture. A plasmid was identified that contained a cDNA insert of 1,466 base pairs coding for human factor IX. The insert is flanked by G-C tails of 11 and 18 base pairs at the 5' and 3' ends, respectively. It also included 138 base pairs that code for an amino-terminal leader sequence, 1,248 base pairs that code for the mature protein, a stop codon, and 48 base pairs of noncoding sequence at the 3' end. The leader sequence contains 46 amino acid residues, and it is proposed that this sequence includes both a signal sequence and a pro sequence for the mature protein that circulates in plasma. The 1,248 base pairs code for a polypeptide chain composed of 416 amino acids. The amino-terminal region for this protein contains 12 glutamic acid residues that are converted to gamma-carboxyglutamic acid in the mature protein. These glutamic acid residues are coded for by both GAA and GAG. The arginyl peptide bonds that are cleaved in the conversion of human factor IX to factor IXa by factor XIa were identified as Arg145-Ala146 and Arg180-Val181. The cleavage of these two internal peptide bonds results in the formation of an activation peptide (35 amino acids) and factor IXa, a serine protease composed of a light chain (145 amino acids) and a heavy chain (236 amino acids), and these two chains are held together by a disulfide bond(s). The active site residues including histidine, aspartate, and serine are located in the heavy chain at positions 221, 270, and 366, respectively. These amino acids are homologous with His57, Asp102, and Ser195 in the active site of chymotrypsin. Two potential carbohydrate binding sites (Asn-X-Thr) were identified in the activation peptide, and these were located at Asn157 and Asn167. The homology in the amino acid sequence between human and bovine factor IX was found to be 83%.
...
PMID:Isolation and characterization of a cDNA coding for human factor IX. 695 30

The sequence homology found by Waxman & Strominger between penicillin-sensitive D-alanine-carboxypeptidases and penicillin-inactivating beta-lactamases is shown to extend to the level of secondary structure as predicted by the method of Chou & Fasman or by the informational method of Garnier et al. Thermodynamic similarity of homologous segments of these proteins is demonstrated by means of a sequence-independent parameter, the hydration potential of Wolfenden at al. Although the 40- to 70-residue amino-terminal sequences examined contain a common serine reactive with penicillins and (in the case of the carboxypeptidases) an R-D-alanyl-D-alanine substrate analog, no homology in secondary structure or hydration potential could be found with a serine protease such as alpha-chymotrypsin.
...
PMID:Secondary structure relations between beta-lactamases and penicillin-sensitive D-alanine-carboxypeptidases. 697 15

The effects of various proteolytic enzymes on the high molecular weight protein (connectin) present in a direct sodium dodecyl sulfate extract of myofibrils from chicken breast muscle were studied in detail. To keep the high molecular weight proteins intact, myofibrils had to be prepared in the presence of EGTA. Trypsin, chymotrypsin, papain, and nagarse readily hydrolyzed connectin (doublet band of titin) and the band 3 protein (N2-line protein). Pepsin did not attack connectin, but digested the band 3 protein and myosin. Calcium-activated neutral proteinase hydrolyzed the band 3 protein, leaving connectin intact. On the other hand, serine protease digested connectin but not the band 3 protein.
...
PMID:Connectin, an elastic protein of muscle. Effects of proteolytic enzymes in situ. 702 43

The serine proteases human leukocyte (HL) elastase, porcine pancreatic elastase, cathepsin G, and bovine chymotrypsin A alpha are inhibited competitively at pH 7.5 by heterocyclic compounds such as 2-substituted 4H-3,1-benzoxazin-4-ones, 4-quinazolines, and 4-chloroquinazolines, N-substituted phthalimides, and by thioesters of N-acylanthranilic acids. The most potent inhibitors have KI values in the 10(-7)--10(-8) M range. The inhibitors with fluoroalkyl or fluoroacyl substituents are much more potent than the alkyl or acyl derivatives. The quinazolinones, chloroquinazolines, and N-substituted phthalimides are quite specific for HL elastase. With HL elastase, an excellent correlation is observed between pKI and the infrared carbonyl-stretching frequency of the inhibitor. It is proposed that the partially polarized carbonyl group of the inhibitor interacts with a partially polarized charge relay system of the serine protease. The substituents on the inhibitors are proposed to interact with the primary substrate binding site of the serine proteases. The results indicate that it is possible to develop non-peptide small molecules which are specific inhibitors for HL elastase.
...
PMID:A new class of heterocyclic serine protease inhibitors. Inhibition of human leukocyte elastase, porcine pancreatic elastase, cathepsin G, and bovine chymotrypsin A alpha with substituted benzoxazinones, quinazolines, and anthranilates. 704 Mar 92

The spicule venoms of Euproctis chrysorrhoea and Euproctis subflava were investigated for their capacity to hydrolyze chromogenic tripeptide substrates with selective affinities for various serine proteases. Seven substrates were assayed with affinities for trypsin and thrombin, trypsin and urokinase, serine proteases, chymotrypsin, glandular kallikrein, plasma kallikrein and plasmin. Venom material has a broad spectrum of affinities for the substrates with relative high plasma kallikrein activities. In E. chrysorrhoea venom, trypsin-like activities predominated, whereas E. subflava venom hydrolyzed, in preference, substrates with an affinity for chymotrypsin. The venoms were fractionated on Sephadex G-100, leading to three fractions, all having serine protease activity. The ratios of substrate specificities were markedly different, indicating that in both caterpillar venom preparations at least two separate serine proteases are present. In addition, in human plasma, inhibitor activity could be detected to the kallikrein activity of E. chrysorrhoea, but not of E. subflava. The trypsin-like activity was not inhibited by human plasma. These and earlier studies warrant the assumption that serine proteases, particularly kallikrein, are major factors in the elicitation of clinical symptoms observed after contact with caterpillar spicules.
...
PMID:Protease activities in the spicule venom of Euproctis caterpillars. 704 29

A nonapeptide Ac-His-Phe-Gly-Cys-D-Phe-Ser-Gly-Glu-Cys-NH2 (XI) cyclized through the cysteines at positions 4 and 9 is synthesized as a model active site for the enzyme alpha-chymotrypsin. A CPK model of XI indicates that the peptide will have a high probability of folding into a conformation in which the two beta-phenyls interact to form a hydrophobic site to one side of the cyclohexyl structure, and the Ser-His-Glu side chains form a hydrogen bonded triad over the plane of cyclopeptidyl structure. Substrates can then bind at the hydrophobic pocket formed by the beta-phenyls and be acted upon by the Ser-His-Glu catalytic triad, as in the enzyme. 1H. n.m.r. shows: (i) multiplet peaks for the phenyl protons in D2O that condense to a singlet in DMSO-d6, (ii) a perturbation of the phenyl protons chemical shift on proflavin association to XI, and (iii) perturbation of the His pKa to a higher value on association of proflavin to XI. These data support the existence of a hydrophobic site and a Glu-His interaction in the peptide. Furthermore, the greater than 10(2) better affinity of proflavin to XI than to AcTrp supports the existence of a hydrophobic site. However, no acceleration of p-nitrophenyl acetate or trans-cinnamoyl imidazole hydrolysis over that of imidazole is observed. The possible reasons for a lack of esterase activity in XI and other peptidyl models of serine protease active sites are discussed.
...
PMID:Synthesis and conformational properties of a synthetic cyclic peptide for the active site of alpha-chymotrypsin. 711 15

Limulus amebocyte lysate was fractionated by heparin-Sepharose chromatography into four components (fractions A, B, C and D). Major coagulation factors, i.e., proclotting enzyme, coagulogen, and proclotting enzyme activating factor precursor (proactivator) in the lysate were eluted, respectively, in fraction A, fraction B and fraction C. Clotting enzyme activity was detected only following recombination of fraction A and fraction C in the presence of endotoxin. The conversion of proactivator to its active form (activator) was an endotoxin-dependent reaction and was inhibited by polymyxin B. Either proactivator is an endotoxin-sensitive factor or another endotoxin-sensitive factor, which activates proactivator, is present in fraction C. Optimal pH for proclotting enzyme activation by activator was broad and ranged from pH 6.0 to 8.0, while that for the endotoxin-mediated activation of proactivator was pH 7.0. No initial latent period was observed during activation of the proactivator or proenzyme. The activator was inhibited by benzamidine, leupeptin, soybean trypsin inhibitor and diisopropyl fluorophosphate, suggesting that the activator is a trypsin-type serine protease. Trypsin, but not thrombin, urokinase, plasmin, papain or alpha-chymotrypsin activated the proclotting enzyme. Therefore, limited proteolysis, i.e., of an arginyl- or lysyl-X bond(s), of the proenzyme molecule is probably involved in its activation.
...
PMID:Fractionation of Limulus amebocyte lysate. Characterization of activation of the proclotting enzyme by an endotoxin-mediated activator. 713 84

The complete amino acid sequence of the gamma-subunit of mouse submaxillary gland 7 S nerve growth factor has been determined from analyses of the peptides generated by cyanogen bromide, trypsin, and chymotrypsin from the naturally occurring fragments. All peptides were sequenced automatically in a spinning-cup sequenator using Polybrene to minimize extractive losses by the solvents employed thoughout the degradation cycles. The gamma-subunit, a serine protease with arginine specificity, contains 233 amino acid residues and shares sequence homology with other proteases of this family. The five disulfide bonds of the gamma-subunit are a subset of the six disulfides present in bovine trypsin, as judged by the location of the half-cystine residues in the primary structure. An N-linked carbohydrate side chain is attached to Asn-78 in at least a majority of tee gamma-molecules.
...
PMID:The amino acid sequence of the gamma-subunit of mouse submaxillary gland 7 S nerve growth factor. 726 6


<< Previous 1 2 3 4 5 6 7 8 9 10

---