Oxido-Reduction States and Natural Homologue of Ubiquinone (Coenzyme Q) in Submitochondrial Particles From Etiolated

A bstract. A procedure for the isolation of submitochondrial particles in quan-tity from etiolated Mung bean (Phaseolus aureus) seedlings is described. Using a combination of acetone extraction and 2 systems of thin layer chromatography ubiqu none has been isolated. The isolated u'biquinone migrates coincident with authentic ubiquinone-10 in reversed phase thin layer partition chromatography, gives a positive Craven's test, and has oxidized and reduced spectra oharacteristic of ubiquinone. The quinone is partially reduced under steady-state electron transfer conditions with both succinate and NADH as substrates and is almost completely reduced under anaerobic conditions with either substrate. The concentration of ubiquinone in the particle is of the order of 4.4 m,zmoles per mg particle protein, approximately equa,l to that found in similar submitochondrial particles from beef heart. It is tentatively concluded that ubiquinone-10 is a functional member of the mitochondrial electron transfer chain of Phaseolus aureus.