Question

Pyruvate stands at a metabolic crossroad. If a molecule of pyruvate was labeled on the carboxyl carbon with 14C14C and converted into four different products, where would the label be in each product?

Answer 1

Pyruvate is converted into acetyl Co-A by pyruvate dehydrogenase. Pyruvate is converted into lactic acid by lactate dehydrogenase. Pyruvate is converted into Oxaloacetate by pyruvate carboxylase. Pyruvate is converted into alanine by aminotransferase.

So if pyruvate is labelled with C14 in its carboxyl carbon then the label C14 will be in carbon of CO2 when pyruvate is converted into acetyl Co-A.

When pyruvate is converted into Oxaloacetate then the label C14 will be on the carboxyl carbon (of one of the carboxyl groups) of the Oxaloacetate.

When pyruvate is converted into lactic acid then C14 will be on the carboxyl carbon of the carboxyl group of lactate.

When pyruvate is converted into alanine then C14 will be on the carboxyl carbon of the carboxyl group of alanine.