The formation of phosphopyruvate in washed particles of kidney and liver

Abstract

Respiring "cyclophorase" preparations of sheep kidney, rat liver or pigeon liver form phosphopyruvate from citrate, alpha-oxoglutarate, succinate, fumarate or malate. The most active tissue was pigeon liver and the highest yields were obtained from fumarate or malate. Under anaerobic conditions phosphopyruvate was formed from oxaloacetate, but not from malate or fumarate; under aerobic conditions malate and fumarate formed phos-phopyruvate more rapidly than oxaloacetate. The formation of phosphopyruvate from malate was not abolished by semicarbazide (0.08 [image]), hydroxylamine (0.005 [image]) or cyanide (0.01 [image]). The major part of the malate used under these conditions was recovered as phosphopyruvate. Phosphopyruvate was not formed from oxaloacetate under these conditions. The interpretation of these facts is discussed. Phosphomalate does not incorporate p32O4 in preparations forming phosphopyruvate and thus is not an intermediate in phosphopyruvate formation from malate. Phosphate esters other than phosphopyruvate accumulate on prolonged incubation; these esters behave chromatographically like 2- and 3-phosphoglyceric acids. The formation of the esters is accounted for by the presence of a fluoride-sensitive enolase in the cyclophorase preparation. Under anaerobic conditions the cyclophorase preparations form small quantities of malate from phosphopyruvate or 3-phosphoglyceric acid.