Factors Concerned with the Oxidation of Reduced Coenzymes, and the Reduction of Cytochrome c in Pea Seedlings

Abstract

IN 1939, Lockhart¹ described a diaphorase I from the stems and roots of 12-day old pea and bean seedlings; this preparation, like Straub's heart diaphorase², catalysed the transfer of hydrogen from reduced coenzyme I to methylene blue. It was obtained as a suspension in phosphate buffer and was not purified further because it was extremely unstable, and no activity remained after two days storage. Soluble, stable preparations of a catalyst with certain properties similar to those of Lockhart's diaphorase have been obtained by the method described below. In this work, whole 6-day old pea seedlings were chosen because it is at this point of germination that the flavin level is highest³. The preparations so obtained, unlike Lockhart's, also showed catalytic activity in the transfer of hydrogen from reduced coenzyme II to methylene blue; diaphorase II has been found in the leaves of chickweed by Whatley⁴. In addition, these pea preparations will catalyse the reduction of ferricytochrome c by either reduced coenzyme I or reduced coenzyme II; these activities have not been reported previously in higher plants.