Sokolove P M, Marsho T V
Biochim Biophys Acta. 1976 May 14;430(2):321-6. doi: 10.1016/0005-2728(76)90088-8.
Slow (greater 1 s) light-induced absorbance changes in the 475-5300 nm spectral region were examined in Type A chloroplasts from spinach. The most prominent absorption change occurred at 505 nm. The difference spectrum for this light-induced increase, its absence in osmotically shocked chloroplasts and restoration by ascorbate, and its sensitivity to dithiothreitol indicate that the absorption change is due to carotenoid de-epoxidatiion. The reaction in intact chloroplasts is characterized by its independence of exogenous ascorbate and a rate constant 3- to 8-fold higher than that reported previously for chloroplasts supplemented with ascorbate. The relevance of carotenoid de-epoxidation to other photosynthetic processes was examined by comparing their sensitivities to dithiothreitol. Levels of dithiothreitol that eliminate the 505 nm shift are without effect on saturated rates of CO2 fixation and do not appreciably inhibit fluorescence quenching. We conclude that carotenoid de-epoxidation is not directly involved in the reactions of photosynthesis or in the regulation of excitation allocation between the photosystems.
对菠菜A型叶绿体在475 - 5300 nm光谱区域中缓慢（大于1秒）的光诱导吸光度变化进行了研究。最显著的吸收变化发生在505 nm处。这种光诱导增加的差示光谱、其在渗透休克叶绿体中的缺失以及抗坏血酸的恢复作用，以及其对二硫苏糖醇的敏感性表明，吸收变化是由于类胡萝卜素脱环氧化作用引起的。完整叶绿体中的反应具有不依赖外源抗坏血酸的特点，其速率常数比先前报道的添加抗坏血酸的叶绿体高3至8倍。通过比较类胡萝卜素脱环氧化作用与其他光合过程对二硫苏糖醇的敏感性，研究了类胡萝卜素脱环氧化作用与其他光合过程的相关性。消除505 nm位移的二硫苏糖醇水平对二氧化碳固定的饱和速率没有影响，也不会明显抑制荧光猝灭。我们得出结论，类胡萝卜素脱环氧化作用不直接参与光合作用反应或光系统之间激发分配的调节。
