A new spectrophotometric assay for enzymes of purine metabolism. IV. Determination of adenosine deaminase.

A new spectrophotometric method for the determination of adenosine deaminase is described. Adenosine is deaminated to inosine, the latter is cleaved by an inosine-guanosine specific nucleoside phosphorylase to hypoxanthine and ribose-1-phosphate. Hypoxanthine can be oxidized further to uric acid by xanthine oxidase or to allantoin by xanthine oxidase and uricase. The hydrogen peroxide formed in these reactions is reduced by catalase to water. In the presence of high concentrations of ethanol, equivalent amounts of acetaldehyde are produced. The acetaldehyde is oxidized NAD(P) dependent and the production rate of NAD(P)H is recorded at 334 nm. The new method is suitable for the detection of adenosine deaminase in whole blood, lymphocytes, sera and tissues.