G Pernicious anemia is caused by impaired absorption of vitamin B12. What is the effect of this impairment on the catabolism of amino acids? Complete catabolism of phenylalanine is blocked by the inability to convert phenylalanine to tyrosine. Complete catabolism of methionine, threonine, isoleucine, and valine is blocked by inability to degrade propionyl‑CoA. Complete catabolism of valine, isoleucine, and leucine is blocked by the inability to oxidize branched chain α‑keto acids. Complete catabolism of phenylalanine is blocked by the inability to degrade homogentisate. What metabolite or metabolites appear in the urine as a result of pernicious anemia? branched chain keto acids phenylpyruvate homogentisate methylmalonic acid