Oxido-Reduction States and Natural Homologue of Ubiquinone (Coenzyme Q) in Submitochondrial Particles From Etiolated Mung Bean (Phaseolus aureus) Seedlings

A procedure for the isolation of submitochondrial particles in quantity from etiolated Mung bean (Phaseolus aureus) seedlings is described. Using a combination of acetone extraction and 2 systems of thin layer chromatography ubiquinone has been isolated. The isolated ubiquinone 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 characteristic 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 mmumoles per mg particle protein, approximately equal 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.