“ Biotin has been implicated … deamination of aspartate, serine , and threonine in bacteria in the deamination of serine in animals in the reductive carboxylation of pyruvate by the malic enzyme, … by the phosphoenolpyruvate carboxykinase in carbamylation reactions, in tryptophan metabolism, in purine synthesis, in protein synthesis, and in carbohydrate metabolism.”