Mechanism of Action
of PDH Complex
E1: pyruvate
decarboxylase -
thiamine
pyrophosphate
TPP removes COOH from pyruvate
leaving
2 carbon fragment that binds
the acyl
fragment to the
TPP.
E2: lipomide reductase transacetylase -
lipoate
2 carbon acyl group is transferred
to one
lipoamide arm, and then to the
other,
to position it for
CoASH transfer.
E3: dihydrolipoyl dehydrogenase-
CoASH,
FAD,
NAD+
acyl group is transferred to CoASH;
the reduced lipoamides transfers
2H's to
E-FAD
--> E-FADH2, and then
E-FADH2 passes H to NAD+
--> NADH
O O
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CH3-C-COOH
-----> CH3-C-SCoA
NAD -----------> NADH
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