Spectrophotometric determination of ribose 1-phosphate

In the course of studies on nucleoside monophosphate metabolism, the need was encountered for a method to determine ribose-1-phosphate. Published assays for ribose-1-phosphate depend either on chromatographic separation of the sugarphosphate, or else on its acid lability which allows it to be determined as a phosphate. The present work describes a less laborious spectrophotometric assay which is both rapid and specific. The basis of the method is the absorbance change at 265 nm associated with the following two-stage enzymatic conversion: ribose-1-phosphate + adenine phosphate + adenosine (adenosine phosphorylase); adenosine + H2O → inosine + NH3 (adenosine deaminase). The change in absorbance was proportional to ribose-1-phosphate concentration at least up to 25 μg/ml. In tests of the assay, it was possible to detect ribose-1-phosphate formation from inosine and phosphate catalyzed by purine nucleoside phosphorylase. Further, the degradation of ribose-1-phosphate by various commercial phosphatases and several tissues or microbial extracts was observed.