Maria Silvina Fornasari asked:
"Could anyone tell me why the principal regulatory steps (presence of
allosteric enzymes) in metabolic pathways are irreversible paths
(DeltaG0<<0)?
Mathematical explanations are welcome."
Hmm. It's easy to give a handwaving answer but I'm not sure it would be
right. If one accepted that close-to-equilibrium reactions would always
have small-to-negligible flux control coefficients it would be OK, but
Henrik Kacser always argued that we had no justification for assuming
this. I think in practice close-to-equilibrium reactions usually do have
small-to-negligible flux control coefficients, but that's hardly a
mathematical explanation.
Someone in Berlin needs to have a look at this question: Stefan?
She also asked:
"Also, I should appreciate if anyone can suggest me a detailed book of
metabolic thermodynamics."
If you mean a compilation of thermodynamic data for metabolic reactions
I can't suggest anything right off, though such things certainly existed
in the past. Hans Krebs was instrumental in getting a lot of the right
measurements made as long ago as the 1950s. For more recent data, try
the series of articles that are being produced by Robert Goldberg. I
can't give you a reference from memory, but if you aren't able to track
them down from this clue I can certainly find out.
If, on the other hand, you mean a thermodynamics book in a biochemical
context, then Westerhoff, H. V. and van Dam, K. (1987) "Thermodynamics
and Control of Biological Free-Energy Transduction" (Elsevier,
Amsterdam) is probably your best bet. You indicate above you aren't
afraid of a mathematical approach... that'll be a good thing.
Hope this helps,
Athel
Home page: http://ir2lcb.cnrs-mrs.fr/lcbpage/athel/home_page.html
MCA FAQ: http://ir2lcb.cnrs-mrs.fr/lcbpage/athel/mcafaq.html
MCA chapter from my book:
http://ir2lcb.cnrs-mrs.fr/lcbpage/athel/fek10/mcai.html
Incidentally, our server is down at the moment, so none of these URLs
will work.
