Purine synthesis, biotin

Biotin is a growth factor for many bacteria, protozoa, plants, and probably all higher animals. In the absence of biotin, oxalacetate decarboxylation, oxalosuccinate carboxylation, a-ketoglutarate decarboxylation, malate decarboxylation, acetoacetate synthesis, citrulline synthesis, and purine and pyrimidine syntheses, are greatly depressed or absent in cells (Mil, Tl). All of these reactions require either the removal or fixation of carbon dioxide. Together with coenzyme A, biotin participates in carboxylations such as those in fatty acid and sterol syntheses. Active C02 is thought to be a carbonic acid derivative of biotin involved in these carboxylations (L10, W10). Biotin has also been involved in... 

Biotin was implicated in purine bio thesis by the observations that (a) the fixation of CO2 was markedly lowered in the tissue nucleic acids of biotin-deficient rats S7), and (b) 5-aminoimidazole ribonucleotide accumulated in biotin-deficient yeast 1S8,1S9). In the latter instance, the addition of aspartic acid to the deficient yeast suppressed the accumulation of the arylamine. Since biotin was thought to be involved in aspartic acid biosynthesis (140, 141), it is likely that the synthesis of this amino acid was limiting in biotin deficiency and that the ect of the deficiency on purine biosynthesis was indirect 142),... 

---