Peroxisomes from Spinach Leaves Containing Enzymes Related to Glycolate Metabolism

Abstract

Abstract Microbodies, designated as peroxisomes because of their enzyme complement, have been isolated from spinach leaves. After grinding leaves in 0.5 m sucrose, the peroxisomes were removed with the broken chloroplast fraction by differential centrifugation. During sucrose density gradient centrifugation, the peroxisomes banded in about 1.9 m sucrose and were separated from mitochondria and chloroplasts. The particles, 0.5 to 1.0 µ in diameter, contained a dense granular stroma surrounded by a single membrane. The leaf peroxisomes contained glycolate oxidase, DPNH-glyoxylate reductase, and catalase. Up to 55% of the activity for these enzymes in spinach leaves have been found in the particulate fractions after the initial centrifugation. The leaf peroxisomes are probably the site of oxygen uptake during photorespiration. No catalase activity was present in chloroplasts after removal of the peroxisomes by density gradient centrifugation. P-Glycolate phosphatase, TPNH-glyoxylate reductase, d-amino acid oxidase, urate oxidase, and peroxidase were not present in leaf peroxisomes.