A new enzymatic method for the determination of glycollate in urine and plasma

An enzymatic assay for the measurement of glycollate in urine and plasma is described. Gycollic acid oxidase (glycollate:oxygen oxidoreductase, EC 1.1.3), extracted from spinach leaves, is used in the enzymatic oxidation of glycollate to produce glyoxylate and hydrogen peroxide. In the presence of peroxidase, the hydrogen peroxide oxidatively couples sulphonated 2,4-dichlorophenol and 4-aminophenazone to form a soluble purple quinoneimine dye. Interfering substances are removed from plasma by deproteinisation and from urine by adsorption onto activated charcoal before analysis. Glycollic acid oxidase also catalyses the oxidation of lactic acid which therefore has to be determined separately. The mean normal urinary glycollate for adults is 0.19 mmol/24 h with no difference between males and females. The mean normal plasma glycollate for adults is 0.17 mmol/l, but higher in males than in females.