SUPEROXIDE REDUCTION AS A MECHANISM OF ASCORBATE-STIMULATED OXYGEN-UPTAKE BY ISOLATED CHLOROPLASTS
SUPEROXIDE REDUCTION AS A MECHANISM OF ASCORBATE-STIMULATED OXYGEN-UPTAKE BY ISOLATED CHLOROPLASTS
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DOI：
10.1016/0006-291x(73)91016-4
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发表时间：
1973-01-01
影响因子：
3.1
通讯作者：
HALL, DO
中科院分区：
文献类型：
--
作者：
ALLEN, JF;HALL, DO
将 1m M 抗坏血酸添加到以甲基紫精 (MV) 作为电子受体的分离叶绿体中，可使摄氧速率增加三倍，并将 ADP O 比率降低至不存在抗坏血酸时的三分之一。抗坏血酸的这些作用可被超氧化物歧化酶 (SOD) 逆转，在没有抗坏血酸的情况下，SOD 对 O 2 吸收或 ADP O 比率几乎没有影响。检测到叶绿体相关 SOD 活性相当于 500 单位/毫克叶绿素。抗坏血酸和SOD 对O 2 吸收的影响在偶联和非偶联叶绿体中相似。结果与抗坏血酸通过超氧化物的还原刺激O 2 吸收的假设一致，超氧化物是由添加的电子受体(MV)的自氧化形成的，并且在不存在抗坏血酸的情况下发生歧化。抗坏血酸似乎不会通过替代水作为光系统 II 供体来刺激 O 2 的吸收。
Addition of 1m M ascorbate to isolated chloroplasts with methyl viologen (MV) as electron acceptor trebled the rate of oxygen uptake and decreased the ADP O ratio to a third of that with no ascorbate present. These effects of ascorbate were reversed by superoxide dismutase (SOD), which in the absence of ascorbate had little effect on O 2 uptake or ADP O ratio. A chloroplast-associated SOD activity equivalent to 500 units/mg chlorophyll was detected. The effects of ascorbate and SOD on O 2 uptake were similar in both coupled and uncoupled chloroplasts. The results are consistent with the hypothesis that ascorbate stimulates O 2 uptake by reduction of superoxide, which is formed by autoxidation of the added electron acceptor (MV), and which dismutates in the absence of ascorbate. Ascorbate does not seem to stimulate O 2 uptake by replacing water as the photosystem II donor.