Succinoxidase Inactivation by a Lecithinase in Barley Seedlings

Abstract

RECENTLY, several investigators^1–6 have isolated mitochondrial fractions from plant tissues which are similar to animal mitochondria in that they are capable of oxidizing all the known substrates of the Krebs citric acid cycle, concomitantly synthesizing adenosine triphosphate from adenylate and inorganic phosphate. However, the oxidative and phosphorylative capacities of mitochondria from different plant tissues vary considerably. For example, mitochondria from oats show much less activity in the oxidation of Krebs-cycle acids than do those from the mung bean; while mitochondria from mung bean hypocotyls are more effective in oxidative phosphorylation than particles from leaves and roots of the same plant^2,3. Paquin (unpublished work) in our laboratory has also observed that the mitochondria from tomato leaves are considerably less active in the oxidation of succinic acid than are those from hypocotyls of the same plant, and that this is accompanied by a higher endogenous oxygen uptake in the former as compared to the latter.