The binding of bicarbonate ions to washed chloroplast grana |
| |
Authors: | Alan Stemler |
| |
Institution: | Carnegie Institution of Washington, Department of Plant Biology, Stanford, Calif. 94305, U.S.A. |
| |
Abstract: | Radioactive labelling techniques show that isolated broken chloroplasts can take up HCO3? in the dark. There are two pools of binding sites for this ion on, or within, the thylakoid membranes. A smaller, high affinity pool exists at a concentration of one HCO3? bound per 380–400 chlorophyll molecules. Removal of HCO3? bound in this pool requires special conditions and results in greater than 90% inhibition of oxygen evolution. The inhibition is fully reversed when HCO3? is added back. HCO3? bound in the small pool does not necessarily exchange with free HCO3? in the dark or in light. Evidence presented suggests that this site is very near the site of action of 3-(3,4-dichlorophenyl)-1,1-dimethyl urea. A second, much larger, pool of HCO3? binding sites also exists in a concentration approaching that of the bulk chlorophyll. These sites have a much lower affinity for HCO3?, and their function has not yet been determined. |
| |
Keywords: | DCMU 3-(3′ 4′-dichlorophenyl)-1 1-dimethylurea SiMo sodium silico-12-molybdate |
本文献已被 ScienceDirect 等数据库收录! |
|