An individual with megaloblastic anemia is found to have a significant folate deficiency. Erythropoiesis is hampered in this man due to his inability to perform which type of enzymatic reaction?
Correct Answer: Methylation
Description: Folic acid is a pteridine vitamin that exists as tetrahydrofolate (TH4) in its most reduced form. TH4 can accept methyl, methylene, or formyl carbons and transfer them as methyl groups. This function is vital in nucleotide and amino acid synthesis. Pantothenic acid is a key vitamin in acyl transfer reactions. It forms pa of coenzyme A, which transfers acyl groups in thiol esters as acetyl CoA, succinyl CoA, and other acyl CoA forms. Impoant vitamins in carboxylation reactions include biotin and vitamin K. Biotin carries the carboxyl group in the pyruvate carboxylase and acetyl CoA carboxylase reactions, and vitamin K is utilized in post-translational carboxylation of amino acid residues in blood clotting factors. Oxidative decarboxylation reactions require thiamine (vitamin B1). Examples include the pyruvate dehydrogenase and alpha-ketoglutarate dehydrogenase complexes. Ref: Janson L.W., Tischler M.E. (2012). Chapter 5. Enzymes and Amino Acid/Protein Metabolism. In L.W. Janson, M.E. Tischler (Eds), The Big Picture: Medical Biochemistry.
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