各種酵母生菌のCytochrome組成の分析 : 酵母の呼吸系に関する研究(第1報)

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A method and several problems are presented for analysing the contents of cytochromes in a respiratory system inside intact yeast cells. The split-beam spectrophotometer designed by Chance's group was used to measure absolute and difference spectra of a yeast suspension. Absolute spectra in aerobic and anaerobic suspensions of yeasts were useful for detecting the presence of pigments insensitive to O_2 and of yeast hemoglobin (y-Hb). Depending on the conditions of culture and the sotrage time of the yeast cells, all or part of the respiratory cytochromes became insensitive to O_2 and remained in an oxidized form even in an anaerobic state. The absolute spectra were also useful in detecting the above phenomenon. In most of the cases where the respiratory cytochromes are reactive to O_2,the difference spectra between the anaerobic and aerobic states in much more useful for the determination of the cytochromes than is the absoluet spectra. In determining cytochromes from the spectra, correction for the effect of multiple reflection due to yeast cells was neccesary, and the correction curve is presented. The presence of y-Hb disturbed the assay of the cytochromes from the difference spectra, but this effect could be compensated for by subtracting a suitable magnitude of "y-Hb・O_2-y-Hb" difference spectrum. Typical examples of the above correction method are presented. In a certain kind of yeast, the constitution of the respiratory cytochromes changed extremely during cultivation, but they are nearly constant in some other yeasts. In determning the cytochrome content, there are still many problems; cytochromes a, b, and c calculated from the difference spectra very likely contain cyt. a_3,cyt. b_2 and other b-type cytochromes, and cyt. c_1,respectively. Therefore, the cytochrome contens were expressed divided into cyt. a(+a_3), b-type cyt., and cyt.c+c_1,in the present investigation and E_<604>-E<630>nm (ε=21mM^<-1>), E_<562>-E_<575>nm (ε=18mM^<-1> cm^<-1>), and E_<551>-E_<540nm> (ε=19mM^<-1> cm^<-1>) were used respectively for the calculation. Fourteen kinds (Saccharomyces 2,Hansenula 2,and Candida 10) of yeasts were cultured under the same conditions until the stationary phase, and the cytochrome contents were analysed. Typical examples of the spectra of respiratory cytochromes are presented. The cytochrome contents, especially those of cyt.a (+a_3), varied considerably and the ratios of cyt. a(+a_3), b-type cyt., and cyt. c+c_1 are generally different with different kinds of yeasts.
社団法人日本生物工学会の論文
1973-09-25

各種酵母生菌のCytochrome組成の分析 : 酵母の呼吸系に関する研究(第1報)

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