Kiyoshi Sugahara

The nucleic acid content of chloroplasts isolated from spinach and tobacco leaves.

Purified chloroplasts of spinach and tobacco leaf were obtained using differential centrifugation. These preparations were found to be entirely free from the subcellular particles smaller than chloroplasts under microscope, though all of the nuclear fragments could not be removed. The ratio of nuclear contaminants to chloroplasts in purified preparation was reduced to about 1:600 in both spinach and tobacco. The analyses of the isolated chloroplasts for nitrogen, dry weight, chlorophylls, and nucleic acid P were performed. It was found that RNA and DNA were preferentially extracted from purified chloroplasts with 0.5 N perchloric acid at 70 °C. and 2 N perchloric acid at 70 °C., respectively. By these modified methods of Ogur and Rosen (11), the values for total nucleic acid, which are about 6–10 times higher than those reported by Jagendorf and Wildman (3), were obtained.