Which of the Following is Seen in the Transaminase Mechanism

Question

Which of the following is seen in the transaminase mechanism?
A)aldimine formed between pyridoxal and lysine residue
B)Schiff base
C)pyridoxamine phosphate that reacts only with an $\alpha$-ketoacid
D)a carbanion that is resonance stabilized as a quinonoid intermediate
E)all of the above

Accepted Answer

All of the choices listed are observed in the transaminase mechanism. Pyridoxal forms an aldimine with a lysine residue, which then undergoes a transamination reaction with a ketoacid to form a Schiff base intermediate. Pyridoxamine phosphate is involved in the regeneration of the pyridoxal-lysine aldimine, and a carbanion intermediate is formed and stabilized by resonance during the reaction.