Department of Biochemistry and Biophysics, Iowa State University, Ames, Iowa 50010.
Plant Physiol. 1972 Jun;49(6):991-3. doi: 10.1104/pp.49.6.991.
Free flavins have been extracted from shoots of etiolated corn (Zea mays L., var. Burpee Snowcross) and from yeast cells and separated from other substances by absorption on resorcinol-formaldehyde resin and talc columns and by thin layer chromatography. Riboflavin was the only free flavin present. Extracts of etiolated shoots of oats (Avena sativa L., var. Multiline E-69 and Clinford) yielded riboflavin plus a second free flavin previously demonstrated in oats. The areas of the chromatograms expected to contain lumichrome were completely clear. After illumination of any of the three organisms with artificial light (1100 ft-c) or sunlight for 6 hours, lumichrome (7,8-dimethylalloxazine) was found. In corn shoots after irradiation by sunlight, the amount of lumichrome present was equivalent to 2.5% of the total free flavin. Lumichrome was identified by thin layer chromatography in six solvent systems (including two two-dimensional systems), by its characteristic fluorescence in acetic acid, by its absorption spectrum, and by formation of a characteristic hydrate in ammonia-containing solutions. A comparison was made with in vitro photolysis of riboflavin and the possible role of photolysis of riboflavin (either free or bound) and of lumichrome formation in photo-responses of plants is discussed. Placing the shoots in the dark for 4 hours after irradiation in sunlight for 6 hours led to no detectable loss of the lumichrome which had been formed.
游离核黄素已从玉米（Zea mays L.，变种 Burpee Snowcross）黄化苗和酵母细胞中提取出来，并通过用间苯二酚-甲醛树脂和滑石粉柱吸附以及薄层色谱法从其他物质中分离出来。核黄素是唯一存在的游离黄素。燕麦（Avena sativa L.，变种 Multiline E-69 和 Clinford）黄化苗的提取物中，除了核黄素之外，还含有第二种游离黄素，该黄素以前在燕麦中已被证明存在。预计含有光黄素的色谱图区域完全清晰。用人工光（1100 英尺烛光）或阳光照射这三种生物 6 小时后，发现了光黄素（7,8-二甲基别嘌呤）。在阳光照射后的玉米苗中，存在的光黄素量相当于总游离黄素的 2.5%。通过在六种溶剂系统（包括两个二维系统）中的薄层色谱法、在醋酸中的特征荧光、吸收光谱以及在含氨溶液中形成特征水合物，对光黄素进行了鉴定。还对体外核黄素光解进行了比较，并讨论了核黄素（无论是游离的还是结合的）光解和光黄素形成在植物光反应中的可能作用。在阳光照射 6 小时后，将苗置于黑暗中 4 小时，不会导致已形成的光黄素发生可检测到的损失。
