Radial paper chromatography and columnar chromatography of the chloroplast pigments of leaves.

Abstract

Abstract 1. 1. Analysis by radial paper chromatography indicates that the principal pigments of the leaves of cocklebur, wheat, oats, barley, violet and Elodea are chlorophylls a and b , lutein with or without zeaxanthin, violaxanthin, neoxanthin and carotene. Additional xanthophylls such as neozeaxanthin, lutein epoxide and eloxanthin were not detectable. These results were confirmed by column chromatography using a variety of adsorbents such as powdered sugar, cellulose, starch, ZnCO 3 and activated magnesia. The separability of the pigments and the chromatographic sequence varied with the adsorbent as well as with the solvent. Inseparability of neoxanthin and violaxanthin mixtures in columns of ZnCO 3 with benzene as the wash liquid may account for some reports that leaves contain lutein epoxide but not neoxanthin and violaxanthin. 2. 2. The chromatographic behavior of the epoxy carotenoid pigments varies with the adsorbent. With magnesia as the absorbent, the epoxy carotenoids were less sorbed than the parent pigments, consequently the epoxy groups are less sorbed than the double bonds that they replace. Conversely, with sugar as the adsorbent, the epoxy carotenoids are more sorbed than the parent pigments, hence, on sugar, the epoxy groups are more sorbed than the double bonds that they replace. When treated with acids, the epoxides were not reconverted to the parent carotenoid pigments. 3. 3. The postulation that O 2 evolution in photosynthetic organisms results from deoxygenation of xanthophyll epoxides is not supported by chemical experience and by the that fact epoxides do not occur in some autotrophic organisms. Accummulating evidence suggests a non-chemical role for the chloroplast pigments in photoxynthesis.