Plant Physiology 71:112-117 (1983)
© 1983 American Society of Plant Biologists
Articles
Effect of Inhibitors on Ammonia-, 2-Oxoglutarate-, and Oxaloacetate-Dependent O2 Evolution in Illuminated Chloroplasts
K. C. Woo
Department of Environmental Biology, Research School of Biological Sciences, Australian National University, P. O. Box 475, Canberra City, A.C.T. 2601, Australia
The evolution of O2 in spinach chloroplasts in the presence of oxaloacetate (OAA) was inhibited by a wide range of dicarboxylates. In contrast, (ammonia, 2-oxoglutarate)-dependent O2 evolution was stimulated by malate, succinate, fumarate, glutarate, maleiate, and L-tartrate although OAA has little effect. This increase in O2 evolution was accompanied by a similar increase in 14C incorporation from [5-14C]oxoglutarate into amino acids which was sensitive to azaserine inhibition. Glutamate and aspartate inhibited (ammonia, 2-oxoglutarate)-dependent O2 evolution, but this inhibition was relieved by the addition of succinate, malate, or fumarate. OAA-dependent O2 evolution also was inhibited by glutamate and aspartate, but succinate, malate, or fumarate had little effect on this inhibition. Phthalonate and n-butyl malonate inhibited (ammonia, 2-oxoglutarate)-dependent O2 evolution competitively with respect to 2-oxoglutarate and uncompetitively with respect to malate. Both these inhibitors inhibited OAA-dependent O2 evolution competitively. This evidence suggests that different mechanisms might be involved in the transport of OAA, 2-oxoglutarate, and malate into the chloroplasts.
|
|
