Pyruvate dehydrogenase
|
|
Pyruvate dehydrogenase (EC 1.2.1.51 (http://ca.expasy.org/cgi-bin/nicezyme.pl?1.2.1.51)) is an allosteric enzyme that transforms pyruvate into acetyl-CoA which is then used in the citric acid cycle.
It is inhibited when either of the three following ratios are increased: [ATP]/[ADP], [NADH]/[NAD+] and [acetyl-CoA]/[CoASH].
Pyruvate dehydrogenase is actually a big complex composed of 60 subunits: 24 pyruvate dehydrogenase (E1), 24 dihydrolipoyl transacetylase (E2) and 12 dihydrolipoyl dehydrogenase (E3).
The global reaction catalysed by pyruvate dehydrogenase is:
- pyruvate + CoA + NAD+ ⇒ acetyl-CoA + NADH + H+ + CO2