Malate Dehydrogenase Isoenzymes in Division Synchronized Cultures of Euglena
AUTOR(ES)
Davis, Barry
RESUMO
Sucrose density gradient centrifugation of broken cell suspensions of autotrophically grown Euglena gracilis Klebs. has allowed the separation of chloroplasts, mitochondria, and peroxisomes. Chlorophyll was taken as a marker for chloroplasts, fumarase and succinate dehydrogenase for mitochondria, and glycolate oxidoreductase for peroxisomes. Peaks of malate dehydrogenase (l-malate-NAD oxidoreductase, EC 1.1.1.37) activity were found in the mitochondrial and peroxisomal fractions. Acrylamide gel electrophoresis showed specific isoenzymes in the mitochondrial and peroxisomal fractions and a third isoenzyme in the supernatant. The mitochondrial isoenzyme which had a Km (oxaloacetate) of 30μm was inhibited by oxaloacetate concentrations above 0.17 mm, an inhibition of 50% being given by 0.9 mm oxaloacetate. The peroxisomal isoenzyme had a Km (oxaloacetate) of 24 μm, was inhibited by oxaloacetate concentrations above 0.13 mm, 50% inhibition being given by 0.25 mm oxaloacetate. Malate dehydrogenase activity in the supernatant did not show inhibition by increasing oxaloacetate concentration, the Km (oxaloacetate) being 91 μm.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=366417Documentos Relacionados
- Photosynthetic Products of Division Synchronized Cultures of Euglena1
- The Regulation of Glycolate Metabolism in Division Synchronized Cultures of Euglena1
- The Effect of Light on the Synthesis of Mitochondrial Enzymes in Division-synchronized Euglena Cultures
- Malate Dehydrogenase Isoenzymes from Cotton Leaves: Molecular Weights
- Induction of Malate Dehydrogenase Isoenzymes in Livers of Young and Old Rats