Expected change in Vitamin B,2 deficiency: (A) Increased homocysteine in urine, (B) Increased methylmalonic acid in urine, (C) FIGLU in urine, (D) Phenylalanine in urine
Answer is B. Ans. is 'b' i.e., Increased methylmalonic acid in urine Isomerization of methvlmalonyl CoA to succinyl CoAIn this reaction, active form of vitamin BI2 is deoxyadenosyl cobalamine.Propionyl-CoA is produced as catabolic end product of some alipathic amino acids andb-oxidation of odd chain fatty acids.Propionyl CoA is then conveed to succinyl CoA through methylmalonyl-CoA.Thus methylmalonyl-CoA is accumulated and excreted in urine as methylmalonic acid (methylmalonate) in vitamin B12 deficiency, i.e. methylmalonic aciduria.