Telfer A, Dhami S, Bishop S M, Phillips D, Barber J
Wolfson Laboratories, Department of Biochemistry, Imperial College of Science, Technology and Medicine, London, U.K.
Biochemistry. 1994 Dec 6;33(48):14469-74. doi: 10.1021/bi00252a013.
By measuring time-resolved luminescence emission at 1270 nm, we have detected singlet oxygen formation by illuminated, reaction centers of photosystem II isolated from Pisum sativum, which is in agreement with earlier work (Macpherson, A. N., Telfer, A., Barber, J., & Truscott, T. G. (1993) Biochim. Biophys. Acta 1143, 301-309). In this paper we show that the yield of singlet oxygen is significantly increased if the number of beta-carotene molecules bound per isolated complex is reduced from two to one. We conclude, therefore, that beta-carotene can act as an effective quencher of singlet oxygen in the photosystem II reaction center. This conclusion is supported by the finding that the rate of light-induced irreversible bleaching of chlorins in the reaction center is increased with decreasing beta-carotene levels. The results demonstrate the direct intermediacy of singlet oxygen in causing photooxidative damage within a biological environment and are discussed, specifically, in terms of the role of beta-carotene in protecting photosystem II against photoinhibition.
通过测量1270纳米处的时间分辨发光发射，我们检测到了从豌豆中分离出的光系统II的光照反应中心产生的单线态氧，这与早期的研究结果一致（Macpherson, A. N., Telfer, A., Barber, J., & Truscott, T. G. (1993) Biochim. Biophys. Acta 1143, 301 - 309）。在本文中，我们表明，如果每个分离复合物结合的β - 胡萝卜素分子数量从两个减少到一个，单线态氧的产量会显著增加。因此，我们得出结论，β - 胡萝卜素可以作为光系统II反应中心中单线态氧的有效猝灭剂。这一结论得到了以下发现的支持：随着β - 胡萝卜素水平的降低，反应中心中叶绿素的光诱导不可逆漂白速率增加。这些结果证明了单线态氧在生物环境中引起光氧化损伤的直接中间作用，并特别讨论了β - 胡萝卜素在保护光系统II免受光抑制方面的作用。
