A 40-year-old man comes to the physician because of a 2-day history of blistering lesions on his face and arms. He says he has had many such episodes over the years. Urine studies show the presence of uroporphyrin III. This compound is synthesized from precursors requiring a vitamin that carries out which of the following functions?
Carboxylation of propionyl-CoA
Decarboxylation of L-dopa
Dehydrogenation of pyruvate
Methylation of dUMP
Methylation of homocysteine
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Cut-to-the-chase Answer (1:06):
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HY USMLE Answer (8:24):
