Products of the oxidation of glycolic acid and L-lactic acid by enzymes from tobacco leaves.

An enzyme catalyzing the oxidation of I-cr-hydroxymonocarboxylic acids has been reported earlier (1). It oxidizes glycolic acid (optimum pH range 7.8 to 8.6) about three times as rapidly as Z-lactic acid (optimum pH 7.6). The enzyme is of particular interest because of its high activity, its wide distribution among green plants, its absence from etiolated plants, its unusually low energy of activation, and because it may function as a terminal oxidase in plants. Glycolic acid, though apparently present in many plants, has not been associated with any physiological function of the plants. In the present investigation, a procedure has been worked out for further purification of the enzyme (Qo2 (N) about 50,000). This enzyme preparation oxidized glycolic acid, via glyoxylic acid, to formic acid and COZ. Lactic acid is oxidized to pyruvic acid.