At the Ciba Symposium On Quinones in Electron Transport (Wolstenholme and O’Connor 1961), the question of names came up SU5402 which led the IUPAC–IUB (International Union of Pure and Applied Chemistry–International Union of Biochemistry) to
appoint a committee to approve STA-9090 concentration suitable names (see IUPAC–IUB Commission on Biochemical Nomenclature 1965); among the names used, the committee chose ubiquinone with a secondary choice of coenzyme Q. They selected plastoquinone over koflerquinone. Advances in equipment and techniques were important factors in our discovery of coenzyme Q and the rediscovery of PQ. In 1956, David Green’s laboratory acquired a recording absorption spectrophotometer which made it possible to record the absorption spectrum from chromatography samples,
just in minutes instead of the hours, as was done earlier when we were plotting the data point by point, obtained from a hand-operated machine. Chromatographic identification selleck inhibitor of the compounds was greatly improved by the development of greasy paper chromatography for separation of coenzyme Q analogs (Lester and Ramasarma 1959). An original chromatogram is seen in Fig. 4 (left panel). Even better resolution was achieved with thin layer chromatography on silica gel coated plates (Fig. 4, right panel; see Crane et al. 1966; Griffiths et al. 1966). Fig. 4 Left panel An original chromatogram is shown here for historical reasons; for further information, write to the author. Right panel Chromatographic separation of lipophilic quinones on paraffin impregnated paper showing separation of plastoquinones A, B, and C. Plastoquinone D is now considered as one of the plastoquinone C group. Other quinones shown are Q10 (coenzyme Q10). K1 (Vitamin K1), PQA20 (Plastoquinone homolog with 20 carbon prenyl side chain), α, β, and γ TQ (Tocopherylquinones). Developed in water:NN-dimethylformamide (2.5/97.5); detection of oxidized quinones was Fenbendazole by leucomethylene blue. (After Crane et al. 1966) Role of plastoquinone in photosynthesis
The study of PQ function by solvent extraction and restoration has the disadvantage that the solvent may modify membranes or create artificial alternative electron transport systems. We measured the effect of light on the redox state of PQ in chloroplasts. We exposed chloroplasts to various intensity of tungsten light and extracted chloroplasts with acidified isooctane to decrease quinol reoxidation. Exposure to low light (600 foot-candles) caused as much as 80% reduction of the endogenous quinones when measured at 255 nm (Table 3). As a further assay, we measured reductant in the extract by the reduction of ferric ions (ferric chloride-dipyridyl). Clearly, PQ was available to electrons from illuminated chloroplasts (Crane et al. 1960). Redfearn and Friend (1961a, b) and Friend and Redfearn (1963) conducted a more extensive study in which they obtained only 15% reduction in light, compared to as much as 80% reduction in our study.