Oxaloacetate, uniformly labeled with radioactive carbon, reacts with glutamate using transaminase and pyridoxal phosphate. Which of the following percentages of the original radioactivity will be found in 2-oxoglutarate (α-ketoglutarate) formed in this reaction?
A) 0%
B) 25%
C) 50%
D) 75%
E) 100%

Question

Quizplus · Accepted Answer

In the aspartate transaminase (AST)-catalyzed reaction, the amine group from glutamate is transferred to OAA, generating aspartate from the OAA and α-ketoglutarate from the glutamate. Therefore, none of the radioactive carbon atoms from OAA will enter the TCA cycle.

Oxaloacetate, Uniformly Labeled with Radioactive Carbon, Reacts with Glutamate Using