Fumarase and Malate DH (MDH)

Question 1

Malate DH

Answer 1

catalyze the oxidation of 2ndary OH to a ketone.
And reduction of NAD+ to NADH.

Dimeric, one domain per SU as rossmann fold (bind Nuc and their derivs) In this case, is NAD+

Has stereospecific Hydride transfer, similar to LDH.

Question 2

Fumarase

Answer 2

conversion of fumarate to L-malate…. looks kind of like a dehydration, but its not simple like that.

Enzyme has multiple enzyme states (not confs), complicated kinetics.

• apparent stereospecific E+ addition of water, like aconitases’s 2nd step…. no Fe-S cluster.

Not clear is there is a carbanion TS or an intermediate.

Question 3

free energy MDH

Answer 3

around 30 KJ/mol to make rxn go (L-malate to OA), citrate synthase will poull this rxn along… will take OA and react with Acetyl-coA to get citrate.