title: The trypsin and chymotrypsin inhibitors in chick peas (Cicer arietinum L). Identification of the trypsin-reactive site, partial-amino-acid sequence and further physico-chemical properties of the major inhibitor.
abstract: The two principal isoinhibitors P-5 and P-6 isolated earlier from the seeds of chick peas (Cicer arietinum L.) by a procedure involving biospecific affinity chromatography on active, matrix-bound trypsin are shown to be the virgin and trypsin-modified forms of the same inhibitor. The virgin inhibitor P-5 consists of a single peptide chain of 66 amino acid residues cross-linked by seven disulfide bridges. Upon interaction with the matrix-bound trypsin under the conditions used the virgin inhibitor P-5 is about 50% converted to P-6 by cleavage of a single Lys-Ser linkage at position 14-15 in the molecule. The resulting tetradecapeptide remains bound to the rest of the molecule by two or four disulfide bridges, but the two fragments representing residues 1-14 and 15-66 separate readily by molecular-sieve chromatography following reductive or oxidative cleavage of the disulfide linkages. The sequence 1-25 was established by Edman degradation.
mesh_terms: D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D001665:Binding Sites; D002268:Carboxypeptidases; D002846:Chromatography, Affinity; D002918:Chymotrypsin / Q000037:antagonists & inhibitors*; D046911:Macromolecular Substances; D008970:Molecular Weight; D010940:Plant Proteins / Q000302:isolation & purification / Q000494:pharmacology; D011485:Protein Binding; D012639:Seeds / Q000032:analysis*; D014361:Trypsin Inhibitors / Q000302:isolation & purification / Q000494:pharmacology
chemical_list: D000596:Amino Acids; D046911:Macromolecular Substances; D010940:Plant Proteins; D014361:Trypsin Inhibitors; D002268:Carboxypeptidases; D002918:Chymotrypsin