Isolation of a low molecular weight active fragment of potato proteinase inhibitor IIb.
A low molecular weight active fragment of potato proteinase inhibitor IIPB was obtained by incubating the inhibitor with an equimolar amount of trypsin [EC 3.4.21.4] at pH 8 and 30 degrees for 16 hr, followed by gel filtration through Sephadex G-50, treatment with trichloroacetic acid, and CM-cellulose chromatography. The purified active fragment consisted of a single peptide chain with a molecular weight of 4,300, comprising 39 amino acid residues. It retained very strong inhibitory activity against chymotrypsin [EC 3.4.21.1] and subtilisin [EC 3.4.21.14]. However, the yield of this active fragment was rather low and was variable. On further incubation with trypsin, it was converted into smaller inactive peptides.
D000596:Amino Acids / Q000032:analysis; D002918:Chymotrypsin / Q000037:antagonists & inhibitors; D006863:Hydrogen-Ion Concentration; D008970:Molecular Weight; D010446:Peptide Fragments / Q000032:analysis; D010455:Peptides / Q000302:isolation & purification / Q000494:pharmacology; D010944:Plants / Q000032:analysis; D011480:Protease Inhibitors; D013056:Spectrophotometry, Ultraviolet; D013381:Subtilisins / Q000037:antagonists & inhibitors; D014357:Trypsin; D014361:Trypsin Inhibitors / Q000494:pharmacology
D000596:Amino Acids; D010446:Peptide Fragments; D010455:Peptides; D011480:Protease Inhibitors; D014361:Trypsin Inhibitors; D013381:Subtilisins; D002918:Chymotrypsin; D014357:Trypsin