June 13 11:00 in the 8th floor conference room 

Conformationally controlled pK-switching in membrane proteins: 
One more mechanism specific to enzyme catalysis?

Armen Y. Mulkidjanian
Division of Biophysics, Faculty of Biology/Chemistry, University of 
Osnabruck, Osnabruck D-49069, Germany

Abstract

A catalytic mechanism, where a strong general acid or base emerges, 
when needed, as a result of an isoenergetic conformational change 
of the enzyme would be introduced. The mechanism can be denoted as 
a conformationally controlled pK-switching. Particularly, the 
mechanism could be identified, mostly from the data on the 
intra-protein proton displacements, in the bacterial photosynthetic 
reaction center, bacteriorhodopsin, cytochrome-bc1 complex, 
photosystem II, and the ATP-synthase.

More generally, the revealed ability of enzymes to go between 
isoenergetic conformations, that differ widely in the reactivity of 
catalytic group(s), may substantially contribute to the catalytic 
power of many other enzymes by helping to store the energy of 
substrate binding in a way that is convenient for the utilization 
of this energy during the rate-limiting step of the catalytic 
cycle.

Reference:

Mulkidjanian, A.Y. 1999.  FEBS Lett., 463, 199-204.