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)

A comparative study of the chymotrypsin-like activity of the purified recombinant ClpP protease and the multicatalytic proteinase from rat liver is presented. The peptidase activity of both enzymes has been analyzed with several synthetic fluorogenic peptides, containing either aromatic or nonpolar amino acids in their P1 position. The respective Vmax, Km, and Vmax/Km were calculated from kinetic experiments. The substrate specificity of the multicatalytic proteinase, as expressed by Vmax/Km values, indicate the following substrate preference: N-Suc-IIW-MCA > N-Suc-LY-MCA > N-Suc-LLVY-MCA > or = N-Suc-AAF-MCA > N-Cbz-GGL-beta-NA > Glut-GGF-beta-NA > FPAM-4-MNA. In the case of the ClpP the order of preference is: N-Suc-LY-MCA > N-Suc-IIW-MCA > N-Suc-LLVY-MCA > or = N-Suc-AAF-MCA > or = N-Cbz-GGL-beta-NA > FPAM-4-MNA (where: N-Suc, N-succinyl-; MCA, 7-amido-4-methyl coumarin; beta-NA, beta-naphthylamide; N-Cbz, N-benzyloxycarbonyl-; 4-MNA, 4-methoxy-beta-naphthylamide; Glut, glutaryl. This similar substrate specificity is further supported by the lack of activity of both enzymes against SY-MCA and N-Suc-AAPF-MCA (known substrates of chymotrypsin), by very reduced activity against N-Suc-AAA-MCA and by no significant activity against LG-beta-NA. The results of mixed substrate experiments have shown that all the peptides that are substrates seem to be hydrolyzed by a single class of chymotrypsin-like site in both enzymes. The substrate specificity studies suggest a possible evolutionary relationship between the catalytic component of the ClpP of Escherichia coli and the multicatalytic proteinase chymotrypsin-like catalytic component. This conclusion is further supported by other circumstantial evidence: the fact that affinity-purified anti-ClpP antibodies cross-react with two polypeptide components of the rat liver multicatalytic proteinase complex, presented here and also shown previously; the known resemblance of both structures at the electron microscope level; and their reported role in the degradation of NH2-end rule substrates.
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PMID:A comparative study of the chymotrypsin-like activity of the rat liver multicatalytic proteinase and the ClpP from Escherichia coli. 840 53

The influence of growth rate of lucerne was investigated on the content of crude protein, NDF, ADF and the in situ degradability of crude protein and organic matter in the rumen of bulls. The content of crude protein decreased significantly (P < 0.05) with the increasing growth rate of lucerne, simultaneously the part of soluble N as per cent of total N decreased also. The effective degradability of crude protein decreased about 10% and the same value of organic matter about 5% in relation to the increasing content of NDF and ADF (P < 0.01) in dependence of the increasing growth rate of lucerne. The digestibility of non degraded crude protein in the rumen was investigated in vitro with pepsin, trypsin and chymotrypsin. The highest value resulted with 75.0% digestibility for this crude protein fraction in the stage of the start of flowering of lucerne.
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PMID:[Effect of growth rate of lucerne on the degradability of crude protein in the rumen and on in vitro digestibility of non-degraded crude protein]. 858 96

The developmental changes of intestinal digestive potential and caecal microbial activity were described in suckling and weaned rabbits according to two feeding programmes. Two groups of thirteen litters were fed from 18 to 42 days old a "High" or a "Medium" NDF:starch ratio diet (resp. 2.7 vs 2.0, groups HL and ML) with similar protein and lipid levels, and from 42 to 70 days old the two groups were fed a "Low" NDF:starch ratio diet (1.7). From 25 to 32 days (weaning), the milk and solid feed intake were 22% and 41% higher in ML group (P<0.05), and the mortality by diarrhoea was 4 units lower (P<0.01). The whole tract digestive efficiency increased by 10% before weaning, and remained steady (organic matter) or decreased (lipids, protein) after weaning. Energy digestibility was 0.623 and 0.686 for High and Medium diets respectively. From 25 to 42 days, total enzymatic activity in intestinal content increased for chymotrypsin (5-fold, P<0.001), lipase (10-fold, P<0.001), amylase (17-fold, P<0.01) and maltase (11-fold, P<0.001), while trypsin doubled after weaning. The feeding programme only affected the amylase and maltase activities, that were higher in HL group (P<0.05). The volatile fatty acids concentration in the caecum was not significantly different among the groups, but it increased by 44% 10 days after weaning. The bacterial fibrolytic enzymes, increased by 30% after weaning and were similar among the two groups. The study revealed that the intestinal digestive maturation and the caecal microbial activity of the rabbit evolved markedly between 3 and 5 weeks of age, and was weakly affected when the NDF:starch ratio decreased from 2.7 to 2.0.
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PMID:Maturation of the intestinal digestion and of microbial activity in the young rabbit: impact of the dietary fibre:starch ratio. 1789 43

Insect digestive chymotrypsins are present in a large variety of insect orders but their substrate specificity still remains unclear. Four insect chymotrypsins from 3 different insect orders (Dictyoptera, Coleoptera, and two Lepidoptera) were isolated using affinity chromatography. Enzymes presented molecular masses in the range of 20 to 31 kDa and pH optima in the range of 7.5 to 10.0. Kinetic characterization using different colorimetric and fluorescent substrates indicated that insect chymotrypsins differ from bovine chymotrypsin in their primary specificity toward small substrates (like N-benzoyl-L-Tyr p-nitroanilide) rather than on their preference for large substrates (exemplified by Succynil-Ala-Ala-Pro-Phe p-nitroanilide). Chloromethyl ketones (TPCK, N- alpha-tosyl-L-Phe chloromethyl ketone and Z-GGF-CK, N- carbobenzoxy-Gly-Gly-Phe-CK) inactivated all chymotrypsins tested. Inactivation rates follow apparent first-order kinetics with variable second order rates (TPCK, 42 to 130 M(-1) s(-1); Z-GGF-CK, 150 to 450 M(-1) s(-1)) that may be remarkably low for S. frugiperda chymotrypsin (TPCK, 6 M(-1) s(-1); Z-GGF-CK, 6.1 M(-1) s(-1)). Homology modelling and sequence alignment showed that in lepidopteran chymotrypsins, differences in the amino acid residues in the neighborhood of the catalytic His 57 may affect its pKa value. This is proposed as the cause of the decrease in His 57 reactivity toward chloromethyl ketones. Such amino acid replacement in the active site is proposed to be an adaptation to the presence of dietary ketones.
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PMID:Insect chymotrypsins: chloromethyl ketone inactivation and substrate specificity relative to possible coevolutional adaptation of insects and plants. 1919 84