Abstract
A method for the isolation and assay for particle-associated succinoxidase and cytochrome oxidase from barley roots is described. Some critical factors for the successful isolation of succinoxidase are the incorporation of cysteine into the homogenizing medium, maintenance of the pH near 7 during extraction and assay, and the avoidance of a dilute particle suspension in the assay. Although cytochrome oxidase is relatively easy to demonstrate, the final concentration of particles in the assay is important. An inhibitor of cytochrome oxidase which is retained even with the washed preparations was found to be associated with the particles. In contrast to previous reports of unsuccessful attempts to demonstrate cytochrome oxidase in barley roots, cytochrome oxidase and also succinoxidase have been isolated from roots of both 2- and 10-day-old seedlings of Cape barley.