Pentcho Valev wrote:
> In fact, the second law in this case takes the
> following form:
>> (k+_catalyzed)/(k+) = (k-_catalyzed)/(k-) /7/
>> By comparing /6/ and /7/ we see that
>> k-_catalyzed = k8(E) /8/
This definition of "k-(catalyzed)" cannot stand. To understand why,
write the original reaction as
k+
C <===> A + B /1'/
k-
and try your definitions on it. Compare results with your formal
treatment of
k+
A + B <===> C /1/
k-
The results must be invariant.
> At the moment I am a bit lazy [...], but k+_catalyzed should satisfy
> the equation
>> Vforward = (k+_catalyzed)(A)(B) /9/
Not true. In that case k+(catalyzed) is not a constant, because
V[forward] depends also on the concentration of the enzyme (no matter
how small it is, in particular, negligibly small compared with [A], [B],
[C]).
> Paul Schlosser started deriving something like that
> recently - I assume it is not difficult.
No, it is not difficult indeed. The formal treatment of the
'specificity number' (which is your k+[catalyzed]) is containd in any
introductory textbook on enzyme kinetics. (Please note that our
frequent correspondent Athel Cornish-Bowden is in the Guiness Book of
Records for the largest number of introductory textbooks with "Enzyme
Kinetics" in the title). I admit it: in asking you to define
k+[catalyzed] I was trying to see if an iquisitive dilettante could
briskly arrive at the 'specificity number' from first principles...
I guess I failed: the human propensity for laziness prevailed again...
:)
--Petr
_____________________________________________________________
Petr Kuzmic Ph.D. * BioKin Ltd. * Madison, WI 53708-8336, USA
pkuzmic at biokin.com * http://www.biokin.com * 608.256.1269 fax
