Insight into catalytic mechanism of papain-like cysteine proteinases

We studied the role of D158 in papain-like cysteine proteinases by using subtilisin Carlsberg, and its chemically modified analog thiolsubtilisin, by applying the proton inventory (PI) method and also by taking into account the pH profiles of the kcat/Km parameter. In the case of thiolsubtilisin, we...

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Bibliographic Details
Published in:Applied biochemistry and biotechnology 2004-07, Vol.118 (1-3), p.171-175
Main Authors: Papamichael, E M, Theodorou, L G, Bieth, J G
Format: Article
Language:English
Subjects:
Cysteine
Papain
Subtilisin
Online Access:Get full text
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Summary:We studied the role of D158 in papain-like cysteine proteinases by using subtilisin Carlsberg, and its chemically modified analog thiolsubtilisin, by applying the proton inventory (PI) method and also by taking into account the pH profiles of the kcat/Km parameter. In the case of thiolsubtilisin, we estimated large inverse solvent isotope effects for kcat/Km, as in papain, whereas for subtilisin we found “dome-shaped” PI, suggesting a completely different mechanism. Finally, the kinetic behavior of thiolsubtilisin presented similarities as well as differences, compared to papain, suggesting a possible role for D158 as part of a catalytic triad in papain-like cysteine proteinases.
ISSN:0273-2289
1559-0291
DOI:10.1385/ABAB:118:1-3:171