Differences in specificity for the interactions of stefins A, B and D with cysteine proteinases.
Four different stefin-type cysteine proteinase inhibitors have been isolated from porcine thymus and skin. Amino acid sequence determination revealed the presence of stefin A and stefin B type inhibitors and two new inhibitors, designated as porcine stefin D1 and stefin D2. Stefin D1 was identified as PLCPI, an inhibitor recently characterized from porcine polymorphonuclear leukocytes [Lenarcic et al. (1993) FEBS Lett. 336, 289-292]. Stefin A is composed of 101 amino acids and has an Mr of 11 391 while stefin B contains 98 amino acids, has an Mr of 11 174 and is N-terminally blocked. All inhibitors were found to be fast-acting inhibitors of papain, cathepsin L and cathepsin S (Ki = 0.009-0.161 nM). Stefins A and B also bind tightly and rapidly to cathepsin H (Ki = 0.027 and 0.069 nM, respectively), while stefins D1 and D2 have been shown to be very poor inhibitors of cathepsin H (Ki = 102-150 nM). The decreased affinity of these inhibitors toward cathepsin B (Ki = 2-1700 nM) was shown to be mainly due to the low second order association rate constants. The presence of a highly negatively charged N-terminus on stefin D1 constitutes a likely structural determinant of inhibitor specificity.[1]References
- Differences in specificity for the interactions of stefins A, B and D with cysteine proteinases. Lenarcic, B., Krizaj, I., Zunec, P., Turk, V. FEBS Lett. (1996) [Pubmed]
Annotations and hyperlinks in this abstract are from individual authors of WikiGenes or automatically generated by the WikiGenes Data Mining Engine. The abstract is from MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.About WikiGenesOpen Access LicencePrivacy PolicyTerms of Useapsburg
