O-18 AND (UC)-C-13 LABELING OF PHOTOSYNTHETIC AND RELATED QUINONES AND THEIR PURIFICATION BY HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY

Different photosynthetic quinones have been labeled on the carbonyl groups by oxygen exchange with (H2O)-O-18 and purified by high performance liquid chromatography on normal phase column with non aqueous solvent mixtures. (UC)-C-13 quinones have been extracted from Spirulina maxima, Synechocystis 6803 and E. coli, grown on C-13 labeled medium and purified on reversed phase columns. Vitamin K-1, plastoquinone PQA(45), ubiquinone Q(8) have been obtained in mg amounts, while different other quinones (menaquinone MK(8), ubiquinones Q(2), Q(7), Q(9), Q(11), plastoquinones A) were present only in trace amounts. Several of these quinones have been used in the reconstitution of the photosynthetic reaction centers, in order to assign the quinone bands in the light-induced Fourier transformed infrared difference spectra of the photoreduction of the primary quinone acceptor.