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[Microbiology] Re: Methyl-Citrate-Cycle - Context and Questions

Keno März Dr.K.No at gmx.de
Sat Mar 4 14:42:16 EST 2006

Bob schrieb:
> The system does not know in advance that the fatty
> acid (FA) has odd or even number of C. It degrades it by 2 C (to make
> acetyl CoA) -- except at the last step, where the C3 acid is left if
> the starting FA is odd. So there is only one C3 unit made.

Hello Bob,
Good Argument (should have figured that out myself), thank you

> I never heard of anything called the methyl citric acid cycle. If that
> is supposed to be some analogy to the citric acid cycle (TCA cycle),
> note that the TCA cycle also works by loss of 2 C. So there is still a
> problem of the extra C somewhere.
> I wouldn't be too surprised if there are various ways to deal with
> propionyl CoA.

In fact, it seems to be a circle similar to the TCA-Cycle, but not the 
same. In this path, Propionyle-CoA is combined with Oxalate
to form Methylcitrate. H2O is split off (what's the correct english word 
therefore anyway?) to form Methyl-Cis-Aconitate. One water is added then 
to form Methyl-Iso-Citrate (hence the name).

Unfortunatly, my Book doesn't cover that...

Is it possible that Methyl-Iso-citrat could be split into Pyruvate and 
Succinate? That would be a nice explanation for what's happening, but I 
could not verify that.

But thanks for your help again :o)


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