各種酵母よりのMitochrondira調製とその性質 : 酵母の呼吸系に関する研究(第2報)

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Cell walls of several kinds of yeasts, of 18 kinds tested, were found to be easily digested with snail gut juice by the addition of pretreatments with cysteine and a proteinase (Pronase). These yeasts were (Candida utilis, C. mycoderma, C. guilliermondii, Hansenula canadensis, S. cerevisiae and S. carlsbergensis), and well preserved mitochondria showing good respiratory control and a high P/O ratio were isolated from them. From a yeasts, Endomyces magnusii, which was not susceptible to the above digestion methods, good mitochondria were also isolated by mechanical disintegration of the cells using a "mill-type glass homogenizer" designed by us. The differene spectra of these mitochondira were measured by the split-beam spectrophotometer (Chance type) between 2 types of reduced states (brought about by anaeroiosis with succinate [2 mM]respiration, or by the addition of dithionite) and an oxidized state (aerobic state). The amounts of cytochrome a(+a_3) and cytochrome(c+c_1)of all mitochondria reduced by succinate respiration were similar to those reduced by dithionite. However, the amounts of b-type cytochromes brought about by succinate reduction were much smaller (1/3-2/3) than those by dithionite. This difference is supposed to be due to the fact that succinate can not reduce some parts of cytochrome b, b_2 and most of cytochrome b_T (and presumably some other unknown b-type cyrochromes, also), while dithionite can reduce all of them. Constitutions of the cytochromes in mitochondria, measured by succinate and dithoionite reduction, were compared with those in cells measured by reduction with endogenous repiration. The respiration proceses of the above mitochondria were recorded by an oxygen electrode apparatus. Mitochondria from Saccharomyces showed the same P/O ratio (1.7) in respiration with both succinate and NAD-linked substrates, while all other mitochondria tested (2 Candida, Hansenula, and Endomyces) showed a higher P/O ratio with NAD-linked substrates (2.1-2.5) than that with succinate (1.7). These results suggest that the phosphorylation site I (around NAD-dehydrogenase, FP_1 or FP_D) is absent from the respiratory system of Saccharomyces while other kinds of yeasts have all 3 phosphorylation sites. This suggestion is in accrodance with the sensitivity of various yeast mitochondria to rotenone. Mitochondria from Saccharomyces were insensitive to this inhibitor but the other mitochondria were allsensitive, as in the case of mammalian mitochondira. Numbers of the isoprenoid chain of coenzyme Q in various yeast mitochondria were determined, but no relation was found between the number and presence or absence of site I.
社団法人日本生物工学会の論文
1973-09-25

各種酵母よりのMitochrondira調製とその性質 : 酵母の呼吸系に関する研究(第2報)

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