Premium
The Importance of the Active Site Histidine for the Activity of Epoxide‐ or Aziridine‐Based Inhibitors of Cysteine Proteases
Author(s) -
Mladenovic Milena,
Schirmeister Tanja,
Thiel Stefan,
Thiel Walter,
Engels Bernd
Publication year - 2007
Publication title -
chemmedchem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.817
H-Index - 100
eISSN - 1860-7187
pISSN - 1860-7179
DOI - 10.1002/cmdc.200600159
Subject(s) - aziridine , proteases , cysteine , active site , histidine , epoxide , chemistry , biochemistry , enzyme , stereochemistry , organic chemistry , catalysis , ring (chemistry)
In the present study the importance of the active site histidine residue (His) for the activity of epoxide‐ or aziridine‐based cysteine protease inhibitors is examined theoretically. To account for all important effects, QM/MM hybrid approaches are employed which combine quantum mechanical (QM) methods that are necessary to describe bond‐breaking and formation processes, with molecular mechanics (MM) methods that incorporate the influence of the protein environment. Using various model systems, the computations exclude a direct proton shift from the active site His residue to the inhibitor, but show that one water molecule is sufficient to establish a very efficient relay system. This relay system allows an easy proton transfer from the active site His residue to the inhibitor and is thus essential for the activity of both types of inhibitors. Differences between the epoxides and the aziridines are discussed, along with some implications for the rational design of optimized inhibitors. The work presented herein represents the first QM/MM study into the mode of action of these important inhibitor classes.