questions about mitochondrial theory of aging

Aubrey de Grey ag24 at
Sun Jan 28 08:29:54 EST 2001

jubjub wrote:

> Heteroplasmic.  "Histochemical and biochemical studies revealed
> heteroplasmic dysfunction of oxidative phosphorylation in the
> patients...."

It means some of the mitochondria are doing oxidative phosphorylation
and some aren't.  Most often used to refer to the mitochondrial
population of individual cells.

> Pleioplasmic.  "amounts of complex IV subunits were markedly
> decreased, together with a quite different polypeptide profile from
> that of control mitochondria, suggesting mitochondrial deterioration
> with pleioplasmic defects of mitochondrial proteins."

Never come across it before.  Seems to mean the same as heteroplasmic.

> What is ADP/O ratio?  I am guessing ADP/oxygen ratio.

Yes, ADP/oxygen.

> What is the significance of this term?  How is oxygen uptake rate
> influenced by the presence or absence of ADP?

Well, mitochondria can't make ATP unless they have ADP.  So if they
have no ADP (which is called "State 4"), they can't use much oxygen,
because oxygen consumption is coupled to ATP synthesis.  The only
oxygen they use is that which is allowed by proton leak.

I think you would find a good bioenergetics textbook helpful.  A very
popular and well-written one is "Bioenergetics 2" by David Nicholls
and Stuart Ferguson.

Aubrey de Grey

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