A deficiency in B6 (pyridoxal phosphate) would negatively impact which of the following pathways: 1. Metabolism of homocysteine to cysteine 2. Metabolism of phenylalanine to tyrosine 3. Conversion of methyl malonyl-CoA to succinyl-CoA

The correct answer is 1.

Explanation:

The metabolism of homocysteine produces a sulfur amino acid that is normally formed from methionine during the fulfillment of its function as a donor of methyl groups. Metabolic fate such as remethylation and transsulfuration, involving the enzymatic forms of the vitamins folacin, B12, and B6, gives rise to homocysteine and mixed disulfides including so-called protein-linked homocysteine, the main form circulating in plasma. B6 deficiency would have a direct impact on the metabolism of homocysteine to cysteine.

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