title: Structure of a novel flavin chromophore from Avena coleoptiles, the possible 'blue light' photoreceptor.
abstract: A yellow chromophore has been isolated from Avena coleoptiles grown in the dark. It had previously been shown by Zenk [Zenk, M. H. (1967) Z. Pflanzenphysiol. 56, 122 - 140] to be a flavin of still unidentified structure, and had been suggested to be the 'blue light' photoreceptor in this organism. The structure of this flavin (F1-X) has been identified as 5'-malonylriboflavin by a combination of physicochemical techniques, and by its identity with a sample obtained synthetically. The 5'-malonylester linkage is relatively labile towards hydrolysis and photolysis, it isomerizes to an equilibrium mixture containing probably the 4' isomer. The electronic spectra of 5'-malonylriboflavin (absorption and fluorescence) are practically identical to those of normal riboflavin (vitamin B2).
mesh_terms: D002352:Carrier Proteins; D055598:Chemical Phenomena; D002621:Chemistry; D002627:Chemistry, Physical; D002523:Edible Grain / Q000032:analysis*; D007536:Isomerism; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D026901:Membrane Transport Proteins; D010786:Photoreceptor Cells / Q000032:analysis*; D012256:Riboflavin / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000302:isolation & purification; D013057:Spectrum Analysis
chemical_list: D002352:Carrier Proteins; D026901:Membrane Transport Proteins; C019079:riboflavin-binding protein; C040712:5'-malonylriboflavin; D012256:Riboflavin