Role of Aldolase in Photosynthesis. I. Enzyme Studies With Photosynthetic Organisms With Special Reference to Blue-Green Algae

Abstract

Several enzymes involved in carbohydrate metabolism were assayed in extracts of blue-green (Anacystis nidulans. Anabaena variabilis, Nostoc muscorum), green (Chlorella pyrenoidosa, Scenedesmus obliquus). red (Chondruscrispus. Porphyridium cruentum) and brown (Ochromonas malhamensis) algae, the photo synthetic bacterium Rhodospirillum rubrum. and spinach. Aldolase was absent from the blue-greens but could be detected in all the other organisms. Glucose-6-phosphate and gluconate-6-phosphate dehydrogenases were especially active in the 3 blue-greens examined and it is suggested that the pentose phosphate pathway is the main method of hexose dissimilation in these organisms. These dehydrogenases were low in the red alga Chondrus crispus but a nonspecific glucose oxidase was very active. It is suggested that the apparent absence of aldolase from some photo-autotrophic organisms makes it likely that the formation of hexoses during photosynthesis does not necessarily proceed by the condensation of 2 molecules of triose phosphate.