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

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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)

Structural studies on a hereditarily abnormal plasminogen, plasminogen Tochigi, have been performed to identify the difference responsible for its lack of proteolytic activity. The plasminogen sample used was from a heterozygote and thus consisted of apparently equal amounts of normal and defective plasminogen molecules. Amino acid sequence analysis of a tryptic peptide isolated from the abnormal plasminogen indicated that Ala-600 (equivalent to Ala-55 in the chymotrypsin numbering system) had been replaced by Thr. No other substitutions in the active-site residues--namely, His-57, Asp-102, and Ser-195--were found. Molecular models for chymotrypsin and the bovine trypsin-pancreatic trypsin inhibitor complex indicate that Ala-55 is very near the active-site His. The Thr at position 55 in plasminogen (plasmin) Tochigi may perturb His-57 such that the proton transfers associated with the normal catalytic process cannot occur in the abnormal plasmin.
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PMID:Plasminogen Tochigi: inactive plasmin resulting from replacement of alanine-600 by threonine in the active site. 621 75

Previous studies in our laboratories (Miyata, T., et al. (1982) Proc. Natl. Acad. Sci. U.S. 79, 6132-6136) showed that the structural defect in a hereditarily abnormal plasminogen, plasminogen Tochigi, is due to replacement of Ala by Thr at position 600 from the NH2-terminal end. In the present studies, two abnormal plasminogens, plasminogens Tochigi II and Nagoya, obtained from other family members were analyzed to identify the structural impairment in these molecules. Amino acid sequence analysis of one of the tryptic peptides isolated, respectively, from plasminogens Tochigi II and Nagoya indicated that in both cases, Ala-600 (equivalent to Ala-55 of the chymotrypsin numbering system) had been replaced by Thr. No other substitutions at the active site and substrate-binding site residues, namely, His-57, Asp-102, Ser-195, and Asp-189, were found in the plasmin light chain variants, indicating that all these residues are intact. Moreover, the NH2-terminal heptapeptide sequences of the plasmin light chain variants isolated from plasminogens Tochigi II and Nagoya were identical to the sequence determined for the normal control. These results indicate that the absence of proteolytic activity of both abnormal molecules is due to the same amino acid substitution as that of previously reported plasminogen Tochigi.
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PMID:Plasminogens Tochigi II and Nagoya: two additional molecular defects with Ala-600----Thr replacement found in plasmin light chain variants. 623 49

The position of phosphothreonine in the predicted primary structure of simian virus 40 large T antigen was determined by different methods. After digestion of large T antigen with trypsin and subsequent two-dimensional peptide mapping, a single peptide containing phosphothreonine could be separated from the bulk of phosphoserine-containing peptides. Its amino acid composition was determined by differential labeling with various amino acids in vivo. The high yield of proline (4.5 mol) within the phosphothreonine peptide indicated that it was derived from the carboxy terminus of large T antigen and had in its unphosphorylated form the sequence Lys-Pro-Pro-Thr-Pro-Pro-Pro-Glu-Pro-Glu-Thr-COOH. A phosphopeptide generated by chymotrypsin could be converted into the tryptic phosphothreonine peptide, indicating that the latter was part of the chymotryptic peptide. The origin of the phosphothreonine-containing peptides was independently confirmed by using an antiserum directed against the carboxy terminus of large T antigen. This serum reacted specifically with the proline-rich, phosphothreonine-containing peptides. Further analysis by partial acid hydrolysis indicated that the internal threonine was phosphorylated. The unusual amino acid composition on both sides of the phosphothreonine and the possible function of this phosphorylation site are discussed.
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PMID:Phosphorylation of threonine in the proline-rich carboxy-terminal region of simian virus 40 large T antigen. 626 15

The 350-residue amino acid sequence of the catalytic subunit of bovine cardiac muscle adenosine cyclic 3',5'-phosphate dependent protein kinase is described. The protein has a molecular weight of 40 862, which includes an N-tetradecanoyl (myristyl) group blocking the NH2 terminus and phosphate groups at threonine-197 and serine-338. Seven methionyl bonds in the S-carboxymethylated protein were cleaved with cyanogen bromide to yield eight primary peptides. These fragments, and subpeptides generated by cleavage with trypsin, pepsin, chymotrypsin, thermolysin, and Myxobacter AL-1 protease II, were purified and analyzed to yield the majority of the sequence. The primary peptides were aligned by analyses of overlapping peptides, particularly of methione-containing tryptic peptides generated after in vitro [14C]methyl exchange labeling of methionyl residues in the intact protein.
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PMID:Amino acid sequence of the catalytic subunit of bovine type II adenosine cyclic 3',5'-phosphate dependent protein kinase. 631 Dec 52

The acid protease B (SLB) of Scytalidium lignicolum was reduced and carboxymethylated and then subjected to tryptic digestion. Five fragments were isolated and some of them were further digested with alpha-chymotrypsin, thermolysin, and dilute acetic acid. The sequence analysis of these fragments and the peptides by conventional methods established the complete amino acid sequence of SLB. The enzyme was composed of 204 amino acid residues with threonine and valine as its amino- and carboxyl-termini, respectively. Locations of three disulfide bridges were also established to be Cys47-126, Cys140-163, and Cys192-201 by enzymatic fragmentation of the denatured and unmodified SLB. Only a slight homology was found in the sequences of SLB and other acid proteases hitherto reported.
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PMID:Complete amino acid sequence of Scytalidium lignicolum acid protease B. 637 Sep 89

Dimethylglycine dehydrogenase (EC 1.5.99.2) and sarcosine dehydrogenase (EC 1.5.99.1) are the folate binding proteins of rat liver mitochondria. These two enzymes contain covalently bound flavin and catalyze similar oxidative demethylation reactions (Wittwer, A. J., and Wagner, C. (1981) J. Biol. Chem. 256, 4102-4108). Flavin-peptides have been purified from these two enzymes after proteolytic digestion by trypsin and chymotrypsin. The spectral and chromatographic properties of these flavin peptides changed after treatment with nucleotide pyrophosphatase in a manner consistent with the conversion of an FAD-peptide to an FMN-peptide. The pKa for pH-dependent fluorescence quenching of the purified flavin-peptides was not affected by borohydride reduction which, in conjunction with the pKa values, indicated that the flavin was covalently linked via the 8 alpha position of the isoalloxazine ring to an imidazole N(3) of a histidine residue. Peptides from both enzymes showed histidylflavin at the N terminus. Amino acid composition and sequence analysis showed that the flavin-peptide from dimethylglycine dehydrogenase was His(flavin)-Ala-Ala-Gly-Leu. Amino acid composition and N-terminal analysis suggested the sequence of the flavin-peptide of sarcosine dehydrogenase was His(flavin)-(Ala, Gly,Thr)-Leu.
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PMID:Identification of the covalently bound flavin of dimethylglycine dehydrogenase and sarcosine dehydrogenase from rat liver mitochondria. 649 Jun 27

Two crude fractions of acid-resistant trypsin inhibitors (apparent molecular masses 44 and 20 kDa, respectively) were prepared from human urine by gel permeation chromatography. From both preparations the pure inhibitors were isolated by high performance liquid chromatography (HPLC). Their N-terminal amino-acid sequences were determined and compared with those of HI-30 and HI-14 as isolated by reversible binding to either immobilized trypsin or immobilized chymotrypsin. The N-terminal amino-acid sequence of the high-molecular mass inhibitor UI-I isolated by HPLC was identical with those of HI-30 and UI-C-I isolated via immobilized trypsin or chymotrypsin, respectively. The low-molecular mass inhibitors UI-II and UI-C-II differ from HI-14 by the N-terminal extension Glu-Val-Thr-Lys-when obtained by HPLC or by the extension Thr-Lys-when obtained via immobilized chymotrypsin, respectively. The comparison of these N-termini with the amino-acid sequence of HI-30 (Ala1-...-Val16-Thr-Glu-Val-Thr-Lys-HI-14) defines the low molecular urinary trypsin inhibitors as proteolytic degradation products of the high-molecular urinary inhibitor. Proteolysis may occur at different bonds. The existing discrepancies in molecular architecture and in molecular masses of the urinary trypsin inhibitors are discussed.
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PMID:Isolation of acid-resistant urinary trypsin inhibitors by high performance liquid chromatography and their characterization by N-terminal amino-acid sequence determination. 650 May 19

The complete primary structure of five chymotrypsin/elastase isoinhibitors isolated from Ascaris lumbricoides was determined by conventional methods. These structures represent the first sequence set for the Ascaris inhibitor family. All five isoinhibitors are single-chain polypeptides crosslinked by five disulfide bridges. Isoinhibitor 1 consists of 63 amino acid residues and has glycine at the N-terminal and histidine at the C-terminal. Isoinhibitors 2-5 all have arginine at the N-terminal, differ at positions 25 and 40, and have different C-terminal regions. Isoinhibitors 2 and 4 have asparagine at positions 25 and serine at position 40, whereas isoinhibitors 3 and 5 have lysine and threonine at these positions, respectively. The different C-terminal regions of isoinhibitors 2-5 account for their varying lengths. Isoinhibitor 1 has no sequence heterogeneity. Frequent repetitions of various dipeptides and one tripeptide are evident along the peptide chain of isoinhibitors 2-5. None of the isoinhibitors contains the aromatic amino acids phenylalanine or tyrosine. Comparison of the amino acid sequence of isoinhibitor 1 with the sequence of isoinhibitors 2-5 shows that they differ at a minimum of 16 positions. The primary structures of isoinhibitors 1-5 from Ascaris do not demonstrate a great degree of homology when compared with the sequence of presently known proteinase inhibitors. However, these isoinhibitors share with a very large number of inhibitor families the presence of half-cystine in the P3 position.
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PMID:The isoinhibitors of chymotrypsin/elastase from Ascaris lumbricoides: the primary structure. 656 98

The thermo- and acid-stable trypsin, chymotrypsin and intracellular proteinases inhibitor (TAS-inhibitor) from rabbit serum was digested by trypsin, and its domain (Mr 6200) with antitryptic activity was obtained in homogeneous state. The N-terminal amino acid sequence of this domain was established by automatic Edman degradation: Thr-Val-Ala-Ala-Cys-Asx-Leu-Pro-Ile-Val-Pro-Gly-Pro-X-Arg-Gly-Ile-Phe-X- Leu-X-Ala-Phe-X-Ala-Val-X-Gly. A high degree of homology of the primary structures rabbit, human and bovine TAS-inhibitors was demonstrated.
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PMID:[Amino acid sequence in the reactive site region of an acid-stable inhibitor of trypsin, chymotrypsin and intracellular proteinases from rabbit serum]. 667 68

Some properties of the protein kinase activity associated with neurofilaments isolated from the brain stem and spinal cord of rats have been investigated. The activity had an apparent Km for ATP of 20 microM, a pH optimum of 8.0 and phosphorylated both serine and threonine residues in neurofilament proteins. Cyclic AMP had no effect on the in vitro reaction and casein was a preferred exogenous substrate in comparison to histone. Phosphopeptide mapping of the 145 kDa subunit from neurofilaments phosphorylated in the presence and absence of microtubule proteins indicated that the neurofilament-associated activity was distinct from the microtubule-associated protein kinase. Limited proteolysis of neurofilaments with chymotrypsin indicated that the enzyme activity was not associated with a domain of the 200 kDa subunit which may form the side-arm projections on neurofilaments.
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PMID:Characteristics of the protein kinase activity associated with rat neurofilament preparations. 668 14


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