Open Accessα-Lytic protease can exist in two separately stable conformations with different His 57 mobilities and catalytic activities
Author(s) -
Kristin Coffman Haddad,
James L. Sudmeier,
Daniel A. Bachovchin,
William W. Bachovchin
Publication year - 2005
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.0409279102
Subject(s) - histidine , enzyme , serine protease , protease , chemistry , catalysis , lytic cycle , protonation , residue (chemistry) , active site , serine , enzyme catalysis , stereochemistry , biochemistry , enzyme assay , biophysics , organic chemistry , biology , virus , ion , virology
alpha-Lytic protease is a bacterial serine protease widely studied as a model system of enzyme catalysis. Here we report that lyophilization induces a structural change in the enzyme that is not reversed by redissolution in water. The structural change reduces the mobility of the active-site histidine residue and the catalytic activity of the enzyme. The application of mild pressure to solutions of the altered enzyme reverses the lyophilization-induced structural change and restores the mobility of the histidine residue and the enzyme's catalytic activity. This effect of lyophilization permits a unique opportunity for investigating the relationship between histidine ring dynamics and catalytic activity. The results demonstrate that His57 in resting enzymes is more mobile than previously thought, especially when protonated. The histidine motion and its correlation to enzyme activity lend support to the reaction-driven ring flip hypothesis.