Chapter 23, Problem 28P

When transaminated, the three branched-chain amino acids (valine, leucine, and isoleucine) form compounds that have the characteristic odor of maple syrup. An enzyme known as branched-chain α-keto acid dehydrogenase converts these compounds into CoA esters. People who do not have this enzyme have the genetic disease known as maple syrup urine disease, so called because their urine smells like maple syrup.

1. a. Draw the compounds that smell like maple syrup.
2. b. Draw the CoA esters.
3. c. Branched-chain α-keto acid dehydrogenase has live coenzymes. Identify them.
4. d. Suggest a way to treat maple syrup urine disease.