This is somewhat related to the topic. I've been working on a
model of the uptake and metabolism of formaldehyde (HCHO) in
the nasal lining (mucus & eptithelium). In water, is "rapidly"
hydrated to form HCH(OH)_2, with an equilibrium constant of
~ 10^4 (conc. of water lumped in, so no units) in favor of the
hydrate. I had been presuming that this occured instantaneously
when HCHO partitioned from air into water (mucus) and hence that
the diffusing species was the hydrate. Then I managed to find
the rate for the back reaction, hence allowing me to model it as
a non-equilibrium process. Basicly, I found that HCHO diffused
so fast that there would still be ~ 30% unhydrated at a distance
of 20 uM into an aqueous phase, which is a good chunk of a cell
diameter. Given the short distances between enzymatic sites in
a cell, if there are intracellular concentration gradients then
I'd think there is a good chance for even 'fast' reversible
reactions to be not at equilibrium.
-Paul
schlosser at ciit.org
