I should know better than to respond to this...., but....
Transition state theory (TST) is not the only game in town so far as
explaining 'how' enzymes work. In fact its chief assumption (a static
energy barrier) is OBVIOUSLY untrue for the highly fluctuating things
that enzymes are. The eponymous book edited by Rick Welch covers a
lot of the early work pointing up alternatives
The Fluctuating Enzyme (ed. Welch, G..R.), John Wiley, New York,
1986.
If the role of a good theory is to have some predictive power as well
(I am not sold on this; most often in science the competition between
theories is actually on the basis of explaining EXISTING facts which
the party line usually likes - or is forced - to ignore, and there
are plenty fo precedents even in my own experience...) then theories
that recognise the role of fluctuations give an obvious explanation
for the (often substantial) effects of VISCOSITY on k-cat, which TST
really has nothing to say about.
Scrutton and Sutcliffe at Leicester review more modern alternative
views based largely on tunnelling. Personally I think these types of
ideas are right on the button, and that many new approaches that have
recently become available to enzymologists will make it obvious that
TST was a seductive but less than optimal way to think about enzyme
catalysis.
Scrutton, N. S., Basran, J. & Sutcliffe, M. J. (1999). New insights
into enzyme catalysis - Ground state tunnelling driven by protein
dynamics. European Journal of Biochemistry 264, 666-671.
Scrutton, N. S. (1999). Enzymes in the quantum world. Biochemical
Society Transactions 27, 767-779.
Sutcliffe, M. J. & Scrutton, N. S. (2000). Enzyme catalysis: over-the-
barrier or through-the-barrier? Trends in Biochemical Sciences 25,
405-408.
Sutcliffe, M. J. & Scrutton, M. S. (2000). Enzymology takes a quantum
leap forward. Philos. Trans. R. Soc. Lond. Ser. A-Math. Phys. Eng.
Sci. 358, 367-386.
This may liven up the newsgroup...
All the best,
Douglas.
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*(Prof.) Douglas B. Kell Phone: +44 1970 622334 *
*Director of Research *
*Institute of Biological Sciences Fax: +44 1970 622354 *
*Cledwyn Building *
*University of Wales, Email: dbk at aber.ac.uk *
*Aberystwyth SY23 3DD, U.K. http://gepasi.dbs.aber.ac.uk/ *
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