Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: CAS:61-90-5 (leucine)
 60,841 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Chymotrypsin is specifically adsorbed at low ionic strength and alkaline pH to hydroxyalkyl methacrylate gels with N-benzyloxycarbonylglycl-D-phenylalanine or N-benzyloxycarbonylglycyl-D-leucine attached through 1,6-hexanediamine. Chymotrypsin is not adsorbed either to the unmodified gel (Spheron) or to the gel with attached, 1,6-hexanediamine (NH2-Spheron). The adsorption of chymotrypsin to Z-Gly-D-Phe-NH2-Spheron was investigated as a function of pH and ionic strength. Trypsin is not adsorbed to this gel. Chymotrypsin isolated from a crude pancreatic extract by affinity chromatography on Z-Gly-D-Phe-NH2-Spheron had the same activity as the enzyme isolated on a column of Spheron, to which the naturally-occurring trypsin inhibitor had been coupled.
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PMID:Affinity chromatography on hydroxyalkyl methacrylate gels. III. Adsorption of chymotrypsin to poly(hydroxyalkyl methacrylates) with covalently bound benzyloxycarbonyl-glycyl-D-phenylalanine and -D-leucine as function of pH and ionic strength. 0 31

Three new protease inhibitors were isolated and purified about 200-fold from hemolymph of silkworm larvae, Bombyx mori, using ion-exchange and affinity chromatography. Two of the three inhibitors were basic proteins (SCI-I had pI 9.4 and SCI-II had pI 9.6) and one was acidic (SCI-III had pI 4.0). The molecular weight of each inhibitor was determined to be 7,000 by the sedimentation equilibrium method. The amino acid composition of the inhibitors were similar except for the contents of Asp, Glu, Ile, Leu, and Lys. Val, His, and Trp were not present in the inhibitors and Met appeared only in SCI-III. The CD spectra of the inhibitors were all similar and indicated a low content of alpha-helical structure (10% at most). Each inhibitor could inhibit the protease and esterase activities of bovine alpha-chymotrypsin at a one-to-one molar ratio, and the dissociation constants were 3.1 X 10(-9)M for SCI-I and II and 1.3 X 10(-8)M for SCI-III. Only SCI-II showed a weak inhibitory activity against bovine trypsin. Subtilisin BPN' and papain were not inhibited by these inhibitors.
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PMID:Chymotrypsin inhibitors from hemolymph of the silkworm, Bombyx mori. 2 86

Crossed immunoelectrophoresis of rat serum demonstrated considerably increased serum concentrations of at least ten different proteins during turpentine-induced inflammation. One protein, which moved during electrophoresis like an alpha 1 globulin, showed a particularly large increase. This protein was purified to homogeneity by ammonium sulfate fractionation followed by chromatography on DEAE-cellulose. Sephadex G-100, and concanavalin A-Sepharose, and finally disc electrophoresis in polyacrylamide gel. It has a molecular weight of 56,000 determined by equilibrium ultracentrifugation. An apparent molecular weight of 68,000 was estimated for the reduced protein by electrophoresis in polyacrylamide gel plus sodium dodecyl sulfate, suggesting that the native protein is composed of a single polypeptide chain. It has an E2801%, 1 cm of 5.2, an isoelectric pH of 4.7, and contains 19% carbohydrate. The protein does not inhibit bovine trypsin or chymotrypsin. Its physical properties and amino acid composition distinguish this protein from all other rat serum proteins hitherto characterized. During acute inflammation, induced 25 h previously, rats incorporated 20 times more [14C]leucine into this particular protein than did normal rats. However, incorporation into total serum protein during acute inflammation increased only slightly. Regardless of whether inflammation was induced by surgical injury or by a subcutaneous turpentine injection, within 48 h the serum concentration of this major acute-phase protein rose from the normal value of 0.46 g/liter to a maximum value of 7.2 g/liter, which constituted 10% of the total serum protein.
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PMID:A rat serum glycoprotein whose synthesis rate increases greatly during inflammation. 9 5

An endopeptidase from the larvae of the hornet Vespa crabro has been purified to homogeneity. The enzyme has been characterized with respect to molecular weight, amino acid compositon, and amino- and carboxyl-terminal sequences. The catalytic properties of the hornet protease are similar to those of bovine chymotrypsin with respect to inactivation by phenylmethanesulfonyl fluoride and carbobenzoxyphenylalanine chloro ketone and preferential peptide bond cleavage at aromatic amino acid residues. In contrast to bovine chymotrypsin, the hornet protease is not inhibited by the basic pancreatic Kunitz inhibitor, soybean inhibitor, or chicken ovomucoid. The molecular weight, as determined by several independent methods, was found to be 14 500. The protease is a single-chain protein containing two disulfide bonds. The terminal sequences are: NH2-Ile-Val-Gly-Gly-Ile-Asp.....Gly-Lys-Tyr-Pro-Tyr-Gln-Val-Ser-Leu-Arg-COOH.
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PMID:Enzymatic and chemical properties of an endopeptidase from the larva of the hornet Vespa crabro. 10 67

Sequencing of chymotrypsin, trypsin, collagenase- and hydroxylamine-derived peptides, using the automated Edman degradation procedure, yielded the complete amino acid sequence of alpha2-CB4 from calf skin collagen (321 residues). Together with the data from earlier work, an uninterrupted sequence in the helical region of the alpha2-chain from residues 1-393 is now known. Glycine is found in every third position of the peptide. Hydroxylation of proline and lysine occurs only in the Y-position of the triplet Gly-X-Y and is not complete in every position. Some residues, such as glutamic acid, leucine, phenylalanine and arginine, are distributed non-randomly between the X and Y-positions and this non-random distribution is different in the alpha1 and alpha2-chains. Comparison of the N-terminal 393 residues from the helical region of the alpha1 and alpha2-chains revealed a nearly identical distribution of charged polar residues arginine, lysine, glutamic and aspartic acids. The distribution of the triplet Gly-Pro-Hyp is simialr in both chains. The remaining residues in the alpha2-chain exhibit a high degree of substitutions when compared with those in the alpha1-chain. Approximately one in every two residues in both the X and Y-positions are substituted.
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PMID:The covalent structure of collagen. The amino-acid sequence of alpha2-CB4 from calf-skin collagen. 17 31

A trypsin inhibitor isolated from a potato acetone powder has been purified by affinity chromatography. This protein inhibits trypsin mole per mole. To a lesser extent it combines also with chymotrypsin and elastase. For trypsin, K1 = 8 X 10(-7) M. The inhibitor has a single polypeptide chain of 207 amino acid residues. It contains no sugar or free sulfhydryl groups. Its extinction coefficient E2801% = 10.3 and its isoelectric point is 6.9. Its molecular weight is of the order of 21 000-22000, as determined by sedimentation equilbrium, by inhibition experiment or from its amino acid composition. These same techniques, taken together with the single band observed at different pH on polyacrylamide gel electrophoresis, indicate that the protein purified is monodisperse. However, the finding of two N-terminal amino acid residues, leucine and aspartic acid, and the different stoichometry observed during the interaction of the inhibitor, either with trypsin or with chymotrypsin and elastase, raises the possibility that our preparation is contaminated by a polyvalent inhibitor not detectable by physiochemical methods.
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PMID:Purification and characterization of a trypsin inhibitor from Solanum tuberosum. 24 76

Although the tripeptides Glu-O-Phosphoserine-Tyr and Glu-O-Phosphoserine-Leu have been identified in embryonic bovine enamel proteins, 1, 2 the issue of whether both sequences occur in each of the phosphopeptides, or whether certain sequences occur in specific peptides only, has recently been resolved by isolating homogeneous samples of E33 and E44. All three of the Ser residues of both peptides are phosphorylated. All three in E3 are in the sequence Glu-O-Phosphoserine-Leu, and all three in E4 are in the sequence Glu-O-Phosphoserine-Tyr. It was not possible to sequence either of the polypeptide chains directly by automatic peptide sequencing. However, a partial sequence of E4 was constructed from data derived from peptides isolated after cyanogen bromide, trypsin and chymotrypsin digestions. The presence of Glu, Tyr and Leu adjacent to and near the O-Phosphoserine [Ser(L)] residues and the 2 degrees, 3 degrees and higher ordered structures of the enamel phosphopeptides may be important in calcium binding and mineralization.
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PMID:Phosphopeptides of enamel matrix. 28 20

This paper presents the experimental details which led to the elucidation of the complete primary structure of S16, a protein which belongs to the small subunit of E. coli ribosomes. Protein S16 was digested with trypsin, alpha-chymotrypsin, and the staphylococcal protease. The resulting peptides were purified on paper and their amino acid composition and sequence were determined. Automatic Edman degradation with a modified sequenator on the complete protein yielded information from the 56N-terminal residues. The combination of all these results led to the following complete amino acid sequence: Met-Val-Thr-Ile-Arg-Leu-Ala-Arg-His-Gly-Ala-Lys-Lys-Arg-Pro-Phe-Tyr-Gln-Val-Val-Val-Ala-Asp-Ser-Arg--Asn-Ala-Arg-Asn-Gly-Arg-Phe-Ile-Glu-Arg-Val-Gly-Phe-Phe-Asn-Pro-Ile-Ala-Ser-Glu-Lys-Glu-Glu-Gly-Thr-Arg-Leu-Asp-Leu-Asp-Arg-Ile-Ala-His-Trp-Val-Gly-Gln-Gly-Ala-Thr-Ile-Ser-Asp-Arg-Val-Ala-Ala-Leu-Ile-Lys-Glu-Val-Asn-Lys-Ala-Ala. The molecular weight derived from the sequence amounts to 9 162.
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PMID:The complete amino acid sequence of protein S16 from Escherichia coli. 33 10

Human granulocyte elastase (EC 3.4.21.11) differs from hog pancreatic elastase in its specificity for synthetic substrates. Although hydrolyzing peptide bonds adjacent to the carboxyl group of alanine, the granulocyte enzyme prefers valine at the cleaved bond, in contrast to the pancreatic enzyme which prefers alanine. Peptide bonds involving the carboxyl group of isoleucine can be hydrolyzed by the granulocyte enzyme but are not hydrolyzed to any significant extent extent by pancreatic elastase. This difference in specificty could explain the lower sensitivity of the granulocyte enzyme to inhibitors containing alanine analogs, such as the peptide chloromethyl ketones and elastatinal. The human granulocyte chymotrypsin-like enzyme differs from pancreatic chymotrypsin by being able to cleave substrates containing leucine in addition to those containing the aromatic amino acids.
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PMID:Sbustrate specificity of the elastase and the chymotrypsin-like enzyme of the human granulocyte. 40 49

The trypsin inhibitors from winged bean seed were isolated by affinity chromatography on trypsin-Sepharose 4B and the components fractionated by chromatography on SP-Sephadex C-25 and Sephadex G-100. The major components, inhibitors 2 and 3 were found to be homogeneous proteins with molecular weights of about 20,000. The inhibitors stoichiometrically inhibited bovine trypsin in the molar ratio of 1 : 1 whereas the inhibition of bovine alpha-chymotrypsin was weak and non-stoichiometric. Amino acid analysis indicated that both the inhibitors contain four cysteine residues and are rich in aspartic acid, glutamic acid, glycine, valine and leucine; however, inhibitor 3 lacks histidine and methionine while inhibitor 2 contains one histidine and three methionines. A minor trypsin inhibitor fraction was also isolated which contained at least three proteins with a molecular weight of about 10,000 and a high content of half-cystine.
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PMID:Isolation and characterization of the trypsin inhibitors from winged bean seed (Psophocarpus tetragonolobus (L) Dc.). 45 47


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