In article <2udiq6$qab at styx.uwa.edu.au> camn at uniwa.uwa.edu.au (Cameron Neylon) writes:
>
>BTW DOn't beleive anyhting a book tells you about how many ATP are
>produced per Oxygen or per electron. Fact is that a lot of the protons
>pumped out actually leak back through the membrane and bypass the ATPase
>altogether. (Brand, harper, Taylor (1993) Biochem J 291:739-748) In
>fact teh percentage that leak back depends on how fast ATP is being
>produced. Probably you end up with about 50-75% of the protons coming
>through the ATPase and therfore about 50-75% of the maximum possible ATP
>production.
>and if you don't add magic molecules essentially *no* protons are pumped to the bulk anyway:
Hitchens, G.D. & Kell, D.B. (1984) On the effects of thiocyanate and venturicidin on
respiration-driven proton translocation in Paracoccus denitrificans. Biochim.
Biophys. Acta 766, 222-232.
The evidence that in these systems the proton pumping is *electrogenic* is close to
nonexistent; those protons that *are* seen are accopanied by symports and antiports
which make their net pumping electroneutral. See e.g.
Kell, D.B. (1988) Protonmotive energy-transducing systems: some physical principles
and experimental approaches. In: Bacterial Energy Transduction (C.J. Anthony, ed.),
pp. 429-490. Academic Press, London.
Kell, D.B. (1992) The protonmotive force as an intermediate in electron transport-
linked phosphorylation: problems and prospects. Curr. Top. Cell. Reg., 33, 279-289.
As you may surmise, these topics are what is referred to as 'controverial'...
Douglas.
