OXIDATIVE PHOSPHORYLATION BY PEA SEEDLING MITOCHONDRIA

Abstract

Using P32in combination with a procedure for quantitative separation of inorganic phosphorus a sensitive method for measuring phosphorylation was devised. It was employed to determine the effects of presoaking seed treatments, and of two inhibitors, 2,4-dinitrophenol (DNP) and malonate, on oxidative phosphorylation by pea seedling mitochondria. The addition of DNP to the reaction mixture resulted in typical uncoupling, but there was an unexpected increase in phosphorylation due to malonate. The length and weight of seedlings presoaked in aerated running water were higher than for those presoaked in standing water; however, mitochondrial preparations from seedlings presoaked in standing water gave higher phosphorylative and oxidative activities. These differences in results were regarded as evidence of 'physiological predetermination'.