Johnson Research Foundation, University of Pennsylvania, Philadelphia, Pennsylvania 19104.
Plant Physiol. 1971 Feb;47(2):282-8. doi: 10.1104/pp.47.2.282.
The oxidation-reduction potentials of the cytochromes of the respiratory chain of mung bean (Phaseolus aureus) mitochondria have been measured under strictly anaerobic conditions with a combined spectrophotometric/potentiometric method. The midpoint potentials at pH 7.2 are as follows: cytochrome a: +190 millivolts; a(3): +380 millivolts; b(553): +75 millivolts; b(557): +42 millivolts; b(562): -77 millivolts; c(547) and c(549): +235 millivolts. (The subscripts refer to the difference absorbance maxima observed for these cytochromes in reduced-minus-oxidized difference spectra recorded at 77 K.) The same values of midpoint potentials at pH 7.2 are obtained with mitochondria depleted of energy by aerobic incubation with ADP and uncoupler in the presence of inorganic phosphate, or with coupled mitochondria energized with ATP in the absence of inorganic phosphate. Coupling site II is placed between b(553)/b(557) and c(549)/c(547) in these mitochondria, and coupling site III is placed between a and a(3).
在严格的厌氧条件下，使用分光光度法/电位法测量了绿豆（Phaseolus aureus）线粒体呼吸链细胞色素的氧化还原电位。在 pH 7.2 时的中点电位如下：细胞色素 a：+190 毫伏；a(3)：+380 毫伏；b(553)：+75 毫伏；b(557)：+42 毫伏；b(562)：-77 毫伏；c(547)和 c(549)：+235 毫伏。（下标是指在 77 K 下记录的还原-氧化差示光谱中观察到这些细胞色素的还原差示吸收最大值的差异。）在有氧条件下用 ADP 和解偶联剂孵育耗尽能量的线粒体，或在没有无机磷酸盐的情况下用 ATP 使耦联线粒体供能，在 pH 7.2 时也得到相同的中点电位值。在这些线粒体中，结合位点 II 位于 b(553)/b(557)和 c(549)/c(547)之间，结合位点 III 位于 a 和 a(3)之间。
