Thioctic Acid and Photosynthetic Fixation of Carbon Dioxide

Abstract

CALVIN and his co-workers¹ have suggested that 6,8-thioctic acid, the prosthetic group of pyruvic oxidase, is a key substance in photosynthesis, since the oxidized and reduced forms of this compound may control the distribution of the fixed carbon into the ‘true’ products of photosynthesis (for example, sugars) and the Krebs-cycle acids. It was proposed that thioctic acid is closely associated with the primary photochemical process², and experimental evidence was advanced in support of the contention that thioctic acid increases the quantum efficiency of the Hill reaction in Scenedesmus^3,4. This communication summarizes the results obtained in an investigation on whether the photosynthetic reduction of carbon dioxide also is stimulated by thioctic acid.