Enzymatic synthesis and properties of 5-phosphoribosylpyrophosphate.

Investigations of the mechanism of pyrimidine nucleotide formation from orotic acid led to the isolation and characterization of an activated ribose phosphate derivative which serves as an intermediate in the overall process. In earlier communications (1) we have described briefly the enzymatic synthesis of this new intermediate, identified as PRPPI (equation (I)), and the occurrence of enzymes which condense pyrimidines and purines with PRPP to form the respective nucleotides (equation (2)).