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 primary structure of rat heart muscle fatty acid-binding protein was investigated by liquid secondary ion mass spectrometry. The protein was digested with trypsin, chymotrypsin, and Staphylococcus aureus V8 protease and the resulting peptides were separated by reverse phase high performance liquid chromatography. The masses of the protonated molecular ions (MH+) of the tryptic, chymotryptic, and S. aureus protease peptides were determined by liquid secondary ion mass spectrometry analysis using 20-500 pmol of material. From the tryptic digest, two peptides with MH+ 1036 and 861 were initially found that did not match the published primary sequence (Sacchettini, J. C., Meininger, T. A., Lowe, J. B., Gordon, J. I., and Banaszak, L. J. (1987) J. Biol. Chem. 262, 5428-5430). The amino acid sequences of these two peptides were determined by a combination of mass spectrometry, B/E-linked scanning, and high performance tandem mass spectrometric techniques to be: (Formula: see text). These new data require that corrections be made to the previously published sequence, involving residues 1-4 and 51-52. The corrected amino sequence for rat m-FABP reveals greater homology with myelin P2, mouse adipocyte p422 protein, and intestinal fatty acid-binding protein than was previously demonstrated.
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PMID:Revision of the blocked N terminus of rat heart fatty acid-binding protein by liquid secondary ion mass spectrometry. 316 35

We have synthesized peptidyl fluoromethyl ketones that are specific inhibitors of the serine proteases alpha-chymotrypsin and porcine pancreatic elastase. By analogy with the corresponding aldehydes it is assumed that the fluoromethyl ketones react with the gamma-OH group of the active site serine to form a stable hemiacetal [Lowe, G., & Nurse, D. (1977) J. Chem. Soc., Chem. Commun., 815; Chen, R., Gorenstein, D.G., Kennedy, W.P., Lowe, G., Nurse, D., & Schultz, R.M. (1979) Biochemistry 18, 921; Shah, D.O., Lai, K., & Gorenstein, D.G. (1984) J. Am. Chem. Soc. 106, 4272]. 19F NMR studies of the chymotrypsin-bound trifluoromethyl ketone inhibitors Ac-Leu-ambo-Phe-CF3 and Ac-ambo-Phe-CF3 clearly indicate that the carbonyl carbon is tetrahedral at the active site of the enzyme. The inhibitor is bound as either the stable hydrate or the hemiacetal, involving the active site serine. The effect of varying the number of amino acid residues in the peptidyl portion of the inhibitor and the number of fluorines in the fluoromethyl ketone moiety is examined. In the series of trifluoromethyl ketone elastase inhibitors, the lowering of Ki concomitant with the change from a dipeptide analogue to a tetrapeptide analogue (Ac-Pro-ambo-Ala-CF3, Ki = 3 X 10(-3) M; Ac-Ala-Ala-Pro-ambo-Ala-CF3, Ki = 0.34 X 10(-6) M) correlates well with the variation in V/K for hydrolysis of the corresponding amide substrates. This trend is indicative of the inhibitors acting as transition-state analogues [Bartlett, P.A., & Marlowe, C.K. (1983) Biochemistry 22, 4618; Thompson, R.C. (1973) Biochemistry 12, 47].(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Inhibition of serine proteases by peptidyl fluoromethyl ketones. 352 55

This study was aimed at investigating the purification, biological activity, and some structural properties of three serine protease inhibitors isoforms, denoted ApTIA, ApTIB, and ApTIC from Acacia plumosa Lowe seeds. They were purified from the saline extract of the seeds, using Superdex-75 gel filtration and Mono-S ion exchange chromatography. They were further investigated by mass spectrometry, spectroscopic measurements, surface plasmon resonance, and inhibition assays with proteases and phytopathogenic fungi. The molecular mass of each isoform was estimated at ca. 20 kDa. Each contained two polypeptide chains linked by a disulfide bridge, with different isoelectric points that are acidic in nature. The N-terminal sequences of both chains indicated that they were Kunitz-type inhibitors. Circular dichroism (CD) analyses suggested the predominance of both disordered and beta-strands on ApTI isoforms secondary structure, as expected for beta-II proteins. In addition, it was observed that the proteins were very stable, even at either extreme pH values or at high temperature, with denaturation midpoints close to 75 degrees C. The isoinhibitors could delay, up to 10 times, the blood coagulation time in vitro and inhibited action of trypsin (Ki 1.8 nM), alpha-chymotrypsin (Ki 10.3 nM) and kallikrein (Ki 0.58 microM). The binding of ApTIA, ApTIB, and ApTIC to trypsin and alpha-chymotrypsin, was investigated by surface plasmon resonance (SPR), this giving dissociation constants of 0.39, 0.56 and 0.56 nM with trypsin and 7.5, 6.9 and 3.5 nM with alpha-chymotrypsin, respectively. The growth profiles of Aspergillus niger, Thielaviopsis paradoxa and Colletotrichum sp. P10 were also inhibited by each isoforms. These three potent inhibitors from A. plumosa may therefore be of great interest as specific inhibitors to regulate proteolytic processes.
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PMID:Physico-chemical and antifungal properties of protease inhibitors from Acacia plumosa. 1944 1