Characterization and Amino Acid Sequence of a New Acidic Cysteine Proteinase Inhibitor (Cystatin SA) Structurally Closely Related to Cystatin S, from Human Whole Saliva1

Abstract
A cysteine proteinase inhibitor (designated as cystatin SA) was isolated from human whole saliva by procedures including chromatography on DE 32 and DEAE-Se-pharose CL-6B. The amino acid sequence determined by conventional methods showed sequence homology of 90 and 87% as compared with the sequences of cystatin S and cystatin SN, respectively, both of which are salivary inhibitors characterized previously. The new inhibitor consisted of 117 residues and had a pI value of 4.3. Cystatin SA inhibited ficin and papain more strongly than cystatin S or cystatin SN did. It also exhibited inhibitory activity toward dipeptidyl peptidase I but the activity was much weaker than those toward ficin and papain.

This publication has 10 references indexed in Scilit: