A Study of Formate Production and Oxidation in Leaf Peroxisomes during Photorespiration

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Abstract
When glycolate was metabolized in peroxisomes isolated from leaves of spinach beet (Beta vulgaris L., var. vulgaris) formate was produced. Although the reaction mixture contained glutamate to facilitate conversion of glycolate to glycine, the rate at which H2O2 became “available” during the oxidation of [1-14C]glycolate was sufficient to account for the breakdown of the intermediate [1-14C]glyoxylate to formate (C1 unit) and 14CO2. Under aerobic conditions formate production closely paralleled 14CO2 release from [1-14C]glycolate which was optimal between pH 8.0 and pH 9.0 and was increased 3-fold when the temperature was raised from 25 to 35 C, or when the rate of H2O2 production was increased artificially by addition of an active preparation of fungal glucose oxidase.