title: Characterization of a proteinase inhibitor from Cajanus cajan (L.).
abstract: A protein proteinase inhibitor (PI) has been purified from pigeonpea Cajanus cajan (L.) PUSA 33 variety by acetic-acid precipitation, salt fractionation and chromatography on a DEAE-Cellulose column. The content of inhibitor was found to be 15 mg/20 g dry weight of pulse. The molecular weight of the inhibitor as determined by SDS-PAGE under reducing conditions was found to be about 14,000. It showed inhibitory activity toward proteolytic enzymes belonging to the serine protease group, namely trypsin and alpha-chymotrypsin. The inhibitory activity was stable over a wide range of pH and temperatures. Estimation of sulfhydryl groups yielded one free cysteine and at least two disulfide linkages. N-terminal sequence homology suggests that it belongs to the Kunitz inhibitor family. Structural analysis by circular dichroism shows that the inhibitor possesses a largely disordered structure.
authors.affiliation: Interdisciplinary Biotechnology Unit, Aligarh Muslim University, Aligarh 202 002, India.
authors.forename: Soghra Khatun
authors.initials: SK
authors.lastname: Haq
authors.forename: Rizwan Hasan
authors.initials: RH
authors.lastname: Khan
mesh_terms: D000818:Animals; D036561:Cajanus / Q000737:chemistry*; D002417:Cattle; D002848:Chromatography, DEAE-Cellulose; D002918:Chymotrypsin / Q000037:antagonists & inhibitors / Q000378:metabolism; D002942:Circular Dichroism; D005453:Fluorescence; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008970:Molecular Weight; D011480:Protease Inhibitors / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology*; D011485:Protein Binding; D020539:Sequence Analysis, Protein; D013438:Sulfhydryl Compounds / Q000032:analysis; D013696:Temperature; D014357:Trypsin / Q000378:metabolism; D014361:Trypsin Inhibitors / Q000302:isolation & purification / Q000494:pharmacology; D014364:Tryptophan / Q000032:analysis; D014443:Tyrosine / Q000032:analysis
chemical_list: D011480:Protease Inhibitors; D013438:Sulfhydryl Compounds; D014361:Trypsin Inhibitors; D014443:Tyrosine; D014364:Tryptophan; D002918:Chymotrypsin; D014357:Trypsin