The Biosynthesis of Carbon-14-Labelled Compounds I. Preparation of 14C-Labelled Starch, D-Glucose, D-Fructose and Sucrose by means of Photosynthesis

C14-labelled starch, D-glucose, D-fructose, and sucrose were prepared in a good yield by means of photosynthesis from a tobacco leaf exposed to an atmosphere of C O/ and to the light. In the preliminary work, some conditions of the photosynthesis method were re-examined and the optimum conditions determined. Following these conditions the tobacco leaf was allowed to perform the photosynthesis in the presence of 38.8 mc of C/sup 14/O/sub 2/. The leaf was killed and extracted with 80% ethanol. The starch of total activities 14.2 mc was extracted from the ethanol insoluble. The starch was then hydrolyzed to D-glucose by dissolving it in sufficient water to make a 0.2% solution, adding an equal volume of 2 N H/sub 2/SO/sub 4/ and refluxing the mixture for 8 hours in the oil bath (125 approximates 130 deg ). The reaction mixture yielded D-glucose. The mixture of D-glucose, D-fructose and sucrose in the 80% ethanol extracts was separated by cellulose column chromatography. After the removal of the ethanol and the chlorophyll, the solution was deionized through ion exchange resin. The deionized sugar solution was concentrated to a small volume in vacuo and added to the cellulose column. The column was developed with 95% n-butanol and then eluted the D-fructose and the D-glucose using the same solvent. After most of the D-glucose was eluted, the composition of the solvent was changed to elute the sucrose. Using this method pure 5.2 mc of D-fructose, 5.3 mc of D-glucose, and 6.8 mc of sucrose were obtained.