anaerobic respiration/nitrate reduction

Oliver, Jim jdoliver at EMAIL.UNCC.EDU
Wed Oct 27 20:10:41 EST 1999


A couple of questions came up in my microbial physiology/metabolism course
which I feel I should have known, but don't.  Any help would be appreciated!

In anaerobic respiration with NO3 as terminal electron acceptor, I have in
my notes that the electron transport chain is much abbreviated (from that
ending with oxygen), with essentially only NADH being oxidized to NAD, and
then a quinone, then nitrate reductase, with nitrate as terminal electron
acceptor.  Question was, unlike electron transport chain where several
protons are pumped out of cell (to establish proton motive force), it
doesn't appar that any protons are pumped out during anaerobic respiration
with nitrate.  Since I believe that the energy yield from anaerobic
respiration with nitrate is nearly as high as aerobic respiration, there
must be some protons pumped out.  What am I missing??

Thanks for all help.
Jim Oliver
Professor of Biology



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