Oxidative Activity of Subcell Particles from a Number of Plant Species

From a comparative biochemical standpoint, it is important to know if plants in general possess subcell particles which, like animal mitochondria, catalyze the reactions of the tricarboxylic acid (TCA) cycle. An understanding of such pathways of carbohydrate metabolism in plants is a prerequisite to a high degree of prediction and control of plant development. A number of workers have obtained subcell fractions, from plants, which were able to catalyze the reactions of the TCA cycle. Millerd et al (14) obtained enzyme particles from etiolated mung bean seedlings, Phaseolus aureus, and from avocado fruit (15), Persea americana. Davies (6) obtained active particles from etiolated pea seedlings, Pisum sativum; Laties (12') reported similar results for particles from cauliflower buds, Brassica oleracea; and Ohmura (16) found TCA cycle activity in particles from green spinach leaves, Spinacia oleracea. Brummond and Burris (4) traced the TCA cycle reactions taking place in particulate fractions from lupine tissue, Lupinus albus. Conn and Young (5) also prepared active particles from etiolated lupine cotyledons. All of the workers mentioned above used sand with a mortar and pestle, as did Kennedy and Lehninger (10), to comminute the tissues being studied. Beaudreau and Remmert (3), using a blendor for homogenization of their plant material, obtained active particles from Black Valentine beans, Phaseolus vulgaris. This blendor method was reported to be superior in some respects as a routine method for the isolation of certain subcell particles from plants. The work described in this paper was an attempt to show that subcell particles, possessing the entire component of TCA cycle enzymes, could be isolated from a number of plant species by using the blendor method. The rates of 02 uptake per unit of nitrogen as well as the percentages of oxidation of added substrates were determined.