Vitamins and Cofactors Flashcards

Thiamine (Vitamin B1) deficiency causes which neurological and cardiovascular condition?

Answer: Beriberi

Thiamine deficiency causes beriberi, characterized by peripheral neuropathy (dry beriberi) or cardiovascular dysfunction (wet beriberi), due to impaired pyruvate dehydrogenase and alpha-ketoglutarate dehydrogenase.

Niacin (Vitamin B3) is a precursor for which essential electron carrier coenzymes?

Answer: NAD⁺ and NADP⁺

Niacin (nicotinic acid/nicotinamide) is the precursor for NAD⁺ and NADP⁺, which are crucial electron carriers in oxidative metabolism and anabolic reactions respectively.

Biotin serves as a cofactor for carboxylase enzymes by acting as a carrier of:

Answer: CO₂ (carboxyl groups)

Biotin is covalently attached to carboxylase enzymes and serves as a mobile carboxyl group carrier, transferring CO₂ in ATP-dependent carboxylation reactions such as those catalyzed by pyruvate carboxylase and ACC.

Vitamin B12 (cobalamin) is required for which two reactions in humans?

Answer: Methionine synthesis and methylmalonyl-CoA mutase reaction

Cobalamin is required for methionine synthase (converting homocysteine to methionine) and methylmalonyl-CoA mutase (converting methylmalonyl-CoA to succinyl-CoA) in the metabolism of odd-chain fatty acids and some amino acids.

Pyridoxal phosphate (PLP), the active form of Vitamin B6, is a cofactor for which class of enzymes?

Answer: Aminotransferases (transaminases) and other amino acid-metabolizing enzymes

PLP forms a Schiff base with amino acid substrates and is essential for aminotransferases, amino acid decarboxylases, and many other enzymes involved in amino acid metabolism.

Riboflavin (Vitamin B2) is the precursor for which two coenzymes?

Answer: FAD and FMN

Riboflavin is the precursor for flavin adenine dinucleotide (FAD) and flavin mononucleotide (FMN), which serve as prosthetic groups for flavoenzymes in oxidative metabolism.