Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.21.4 (trypsin)
 42,187 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The non-collagenous N-terminal segment of type I procollagen from dermatosparactic sheep skin was isolated in the form of the peptide Col 1 from a collagenase digest of the protein. The peptide has a blocked N-terminus, which was identified as pyrrolid-2-one-5-carboxylic acid. Appropriate overlapping fragments were prepared from reduced and alkylated peptide Col 1 by cleavage with trypsin at lysine, arginine and S-aminoethyl-cysteine residues and by cleavage with staphylococcal proteinase at glutamate residues. Amino acid sequence analysis of these fragments by Edman degradation and mass spectrometry established the whole sequence of peptide Col 1 except for a peptide junction (7--8) and a single Asx residue (44), and demonstrated that peptide Col 1 consists of 98 amino acid residues. The N-terminal portion of peptide Col 1 (86 residues) shows an irregular distribution of glycine, whereas the C-terminal portion (12 residues) possesses the triplet structure Gly-Xy and is apparently derived from the precursor-specific collagenous domain of procollagen. The central region of the peptide contains ten cysteine residues located between positions 18 and 73 and shows alternating polar and hydrophobic sequence elements. The regions adjacent to the cysteine-rich portion have a hydrophilic nature and are abundant in glutamic acid. The data are consistent with previous physicochemical and immunological evidence that distinct regions at the N- and C-termini of the non-collagenous domain possess a less rigid conformation than does the central portion of the molecule.
 ...
PMID:Amino acid sequence of the N-terminal non-collagenous segment of dermatosparactic sheep procollagen type I. 47 72

This report describes an immunoferritin labeling study of mouse H-2 histocompatibility antigens on epithelial cells dissociated from the small intestine by EDTA and trypsin. Before cell dissociation, the intestine was prefixed in paraformaldehyde or periodate-lysine-paraformaldehyde in order to preserve the shape of the cells and to immobilize H-2 antigens in their native positions. The results demonstrated the presence of H-2 antigens on the lateral and basal cell membranes at about the same high density that was observed at the surface of mouse monocytes. No H-2 antigens could be detected at the apical surface of dissociated or undissociated epithelial cells. It is unlikely that the fuzzy coat masked H-2 antigens at the apical surface because it was essentially absent from the apical membranes of dissociated cells. These observations extend our knowledge of the cellular distribution of transplantation antigens, and provide further evidence of a discontinuity in the expression of membrane components at the junctional complex of epithelial cells.
 ...
PMID:The occurrence and distribution of H-2 antigens on mouse intestinal epithelial cells. 47 52

1-Acyl-2-(7-(4-azido-2-nitrophenoxy)-[1-14C]heptanoly)-sn-glycero-3-phosphocholine was synthesized in order to study the lipid-binding site of the phosphatidylcholine exchange protein from bovine liver. Photosensitive phosphatidylcholine was incorporated into the protein by incubation with vesicles of this phosphatidylcholine derivative. The lipid-protein complex was separated from the vesicles by chromatography on Biogel A-0.5m. Photolysis of the complex by irradiation with light of a high pressure mercury lamp at a wavelength above 340 nm generated the highly reactive nitrene. Sodium dodecyl sulfate gel electrophoresis of the photolysed complex indicated that 30% of the endogenous 14C-labeled phosphatidylcholine was covalently linked to the protein. Peptides were isolated after digestion of the photolysed complex with protease from Staphylococcus aureus and trypsin. It was determined that the 2-acyl chain of the phosphatidylcholine molecule was linked to the peptide segment -Gly-Ser-Lys-Val-Phe-Met-Tyr-Tyr-. This segment was part of a protease peptide of about 65 residues of which the sequence was determined by Edman degradation for the first 38 residues. This peptide contains a cluster of apolar residues -Val-Phe-Met-Tyr-Tyr-Phe with an extremely high hydrophobicity index and with a predicted beta-sheet conformation. It is concluded that this hydrophobic cluster forms part of the binding site.
 ...
PMID:Determination of the hydrophobic binding site of phosphatidylcholine exchange protein with photosensitive phosphatidylcholine. 49 8

The primary structure of the membrane-binding segment of rabbit cytochrome b5 has been determined. This segment, prepared by trypsin digestion of the intact protein, consists of 43 amino acid residues and corresponds to the COOH-terminal end (residues 91-133) of the parent molecule. Deduction of the primary structure was based on automated sequence analysis of the whole segment as well as manual and dansyl-Edman degradations of peptide fragments produced by CNBr cleavage and partial acid hydrolysis. The sequence obtained is: Leu-Ser-Lys-Pro-Met-Glu-Thr-Leu-Ile-Thr-Thr-Val-Asn-Ser-Asn-Ser-Ser-Trp-Trp-Thr-Asn-Trp-Val-Ile-Pro-Ala-Ile-Ser-Ala-Leu-Ile-Val-Ala-Leu-Met-Tyr-Arg-Leu-Tyr-Met-Ala-Asp-Asp. This sequence is 63 to 81% homologous with respect to those determined for the membrane-binding segments of equine, porcine and bovine cytochrome b5. The interaction of this segment with phospholipid bilayer membranes is discussed, and a prediction of its secondary structure is also presented.
 ...
PMID:Primary structure of the membrane-binding segment of rabbit cytochrome b5. 50 May 81

The arrangement of 8 histones in the nucleosome core has been investigated by identifying the sites of 4 histone sequences cross-linked with a bifunctional amino-group reagent, dimethyl suberimidate, selected from among 4 diimidoesters of various linker lengths examined. H1-depleted calf thymus chromatin was allowed to react with 14C-labeled suberimidate at pH 8.5 and 0 degrees C. The cross-linked chromatin was then digested exhaustively with trypsin. Almost all the histone fragments were released from the chromatin with 0.25 M HCl and chromatographed on several columns and on paper. Cross-linked peptides were detected by analyzing the content of radioactive suberimidoylbislysine after acid hydrolysis. The chromatographic procedure developed here showed that the whole histone fragments contained 29 mol% of the total linked reagent as suberimidoylbisylsine. The 5 finally purified cross-linked peptides were identified from the total and N-terminal amino acids of each pair of peptides separated by two-dimensional cellulose thin layer chromatography after cutting the linker by ammonolysis. Thus, intramolecular cross-linking was found between Lys-5 and Lys-9 of H2A, and Lys-34 and Lys-85 of H2B, while intermolecular cross-linking was found between Lys-24 (or 27) of H2B and Lys-74 of H2A, Lys-85 of H2B and Lys-91 of H4, and Lys-120 of H2B and Lys-115 of H3 and/or Lys-77 of H4. Most of these lysine residues are located in the DNA-binding segments of the 4 histone sequences identified previously [Kato, Y. & Iwai, K, (1977) J. Biochem. 81, 621--630]. All the 5 or 6 cross-links can be located in a heterotypic tetramer consisting of one molecule each of H2A, H2B, H3, and H4, and a model of the histone arrangement in the tetramer is proposed. Two such tetramers may compose to the histone octamer in the nucleosome core.
 ...
PMID:Identification of suberimidate cross-linking sites of four histone sequences in H1-depleted chromatin. Histone arrangement in nucleosome core. 52 33

The reversible inhibition of the enzymatic activity of trypsin by heparin was investigated. On the basis of an analysis of the Lineweaver-Burk and Dixon graphs, a noncompetitive nature of the inhibition of the BAPA amidase activity of trypsin by heparin was detected, and the values of Km and Ki were determined, equal to 3.1 . 10(-4) and 3.7-3.9 . 10(-7) M, respectively. A comparison of these values indicates a great affinity of heparin for the enzyme. It was shown that heparin inhibits the BAEE esterase activity of trypsin and at the same time has no inhibiting effect on acetyltrypsin. Considering that the acetylation of trypsin leads to selective blocking of the epsilon-amino groups, it was concluded that the epsilon-amino groups of the lysine residues of the trypsin molecule participate in the interaction with heparin.
 ...
PMID:Investigation of the interaction of trypsin with heparin. 54 62

Reductive methylation has little or no detectable effect on the catalytic or physicochemical properties of bovine trypsin but reduces its susceptibility to autolysis. Increased stability after methylation appears to result from the conversion of trypsin-susceptible lysine residues to trypsin-resistant epsilon-N,N-dimethyllysine residues. Reductively methylated trypsin is easily prepared and may be useful in place of trypsin where autolysis is otherwise difficult to control.
 ...
PMID:Stabilization of bovine trypsin by reductive methylation. 56 Feb 14

Casein epsilon-aminolysyl residues were converted to the methyl (and dimethyl), isopropyl or cyclopentyl derivatives in high yield with formaldehyde, acetone or cyclopentanone, respectively, in the presence of sodium borohydride. When incorporated into diets at 10% as the sole protein source, the chemically modified caseins failed to support growth of young rats. Methyl casein did, however, support limited growth after about 5 days. Plasma threonine levels increased and lysine levels decreased markedly in rats fed the alkyl caseins. The respective alkyllsine derivatives were present in plasma and urine. In another experiment, nearly normal or normal growth was obtained by feeding lysine-supplemented methyl or isopropyl casein, respectively. A preparation of partially methylated casein, containing approximately equal amounts of monomethyl- and dimethyllysines, supported normal rat growth. These results demonstrate that lysine deficiency was produced by feeding highly alkylated caseins. Digestibility of the chemically modified caseins in vivo was not affected, although in vitro studies with trypsin and alpha-chymotrypsin showed lowered digestibility. Since no apparent toxicity was observed limited methylation of food proteins may be useful for protection of lysyl residues against deteriorative reactions during processing and storage.
 ...
PMID:Effect of reductive alkylation of the epsilon-amino group of lysyl redsidues of casein on its nutritive value in rats. 56 44

The possibility of producing L-lysine from chemically synthesized DL-lysine has been investigated. Optical resolution of racemic DK-lysine may be achieved by using the stereospecific esterasic activity of trypsin on DL-lysine methyl ester, which gives L-lysine and unchanged D-lysine methyl ester. SL-lysine methyl ester spontaneous hydrolysis may be neglected when operating at pH 5.5 and 30 degrees C. Effect of pH and substrate concentration on hydrolysis rate has been investigated when using as a catalyst either soluble or immobilized trypsin. For this purpose, trypsin was coupled onto an amine porous silica, Spherosil, activated with glutaraldehyde. The optimal pH is 5.8 for soluble trypsin and 6.0 for immobilized trypsin. It was yet possible to lower the parent optimal pH of immobilized trypsin, and thus increase its activity at 5.5, by co-grafting onto Spherosil an aminosilane, for enzyme coupling via glutaraldehyde activation and a positively charged diethyl amino ethyl (DEAE) silane, for decreasing the pH of trypsin microenvironment.
 ...
PMID:Production of L-lysine by immobilized trypsin. Study of DL-lysine methyl ester resolution. 56 19

A commercial preparation of bovine trypsin was treated with methyl acetimidate-HCl, and most of the lysine residues were converted to trypsin-resistant residues retaining their cationic charges. The modified preparation was then fractionated by ion-exchange chromatography on SE-Sephadex C-50 into two active components, amidinated alpha- and amidinated beta-trypsins. The latter component (Am-beta-trypsin), which consisted of a single polypeptide chain, was allowed to autolyze at pH 7.8, 25 degrees C for 3.5 h and a new active component named Am-delta-trypsin was isolated from the autolysate. Several lines of experimental evidence indicated that Am-delta-trypsin was derived by primary cleavage of the bond Arg105-Val106. Cleavage at Arg55-Leu56, on the other hand, appeared to lead to inactivation of Am-beta-trypsin. The kinetic properties of the catalytic hydrolyses of synthetic substrates and the affinity to Gly-Gly-Arg immobilized on Sepharose were compared among Am-delta-, Am-beta-, and Am-alpha-trypsins. Am-delta-trypsin resembled Am-beta-trypsin in these properties, but did not resemble Am-alpha-trypsin which had a cleavage at Lys131-Ser132.
 ...
PMID:Characterization of active derivatives produced by acetamidination and selective autolysis of bovine trypsin. 57 May 66


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