Purification and Structure of a Novel Cysteine Proteinase Inhibitor, Strepin P-1

Strepin P-l, a new proteinase inhibitor, is a low molecular weight peptide isolated from the culture fluid of Streptomyces tanabeensis (SAB-934). Strepin P-l strongly inhibited not only cysteine proteinases, calpain and papain, but also trypsin. The purification procedures included HP-20 adsorption chromatography, DEAE-cellulose, Amberlite CG-50, Sephadex LH-20 and G-25 column chromatography. The yield was 12mg from 8 liters of culture fluid. The proteinase inhibitor thus prepared was a peptide composed of tyrosine, valine and argininal, that reacted positively with Sakaguchi and Pauly reagents on TLC. The N-terminal amino acid, tyrosine, was blocked with an isovaleryl group and the structure was elucidated to be AMsovaleryl-tyrosyl-valyl-argininal. The amino acid sequence-inhibitory activity relationships of strepin P-l, leupeptin and antipain toward calpain and papain are also discussed.