A Spectrophotometric Assay of ATP Synthesized by Sarcoplasmic Reticulum

Abstract

The problems encountered with a coupled enzyme assay for ATP using glucose, hexokinase and glucose-6-phosphate dehydrogenase are discussed and a modification where fructose and glucosephosphate isomerase were substituted for glucose is described. This modified assay was used successful1y to measure the ATP synthesized by reversal of the sarcoplasmic reticulum ATPase. ATP synthesized by adenylate kinase contaminating the sarcoplasmic reticulum was easily corrected for by a subtraction procedure.