Characterization and amino acid sequence of a new acidic cysteine proteinase inhibitor (cystatin SA) structurally closely related to cystatin S, from human whole saliva.
A cysteine proteinase inhibitor (designated as cystatin SA) was isolated from human whole saliva by procedures including chromatography on DE 32 and DEAE-Sepharose 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.
Department of Oral Biochemistry, Nippon Dental University School of Dentistry at Niigata.
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Isemura
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Saitoh
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Sanada
D000595:Amino Acid Sequence; D055598:Chemical Phenomena; D002621:Chemistry; D015891:Cystatins; D003546:Cysteine Endopeptidases; D006801:Humans; D008969:Molecular Sequence Data; D010446:Peptide Fragments; D011480:Protease Inhibitors; D012463:Saliva / Q000032:analysis*; D055333:Salivary Cystatins; D012471:Salivary Proteins and Peptides
C525171:CST1 protein, human; C525172:CST2 protein, human; C525173:CST4 protein, human; D015891:Cystatins; D010446:Peptide Fragments; D011480:Protease Inhibitors; D055333:Salivary Cystatins; D012471:Salivary Proteins and Peptides; D003546:Cysteine Endopeptidases