Knaff D B, Malkin R, Myron J C, Stoller M
Biochim Biophys Acta. 1977 Mar 11;459(3):402-11. doi: 10.1016/0005-2728(77)90041-x.
Extraction of Triton Photosystem II chloroplast fragments with 0.2% methanol in hexane for 3 h results in the removal of 90 to 95% of the plastoquinone in the original preparation. The extracted fragments (chlorophyll:plastoquinone ratio, 900: 1) showed no P-680 photooxidation at 15 K after a single laser flash. The extracted fragments also showed no light-induced C-550 absorbance change at 77 K. Reconstitution of the primary reaction of Photosystem II, as evidenced by restoration of low-temperature photooxidation of P-680, could be obtained by the addition of plastoquinone A but not by the addition of beta-carotene. The addition of beta-carotene plus plastoquinone A restored the C-550 absorbance change. These results indicate that plastoquinone functions as the primary electron acceptor of Photosystem II and that beta-carotene does not play a direct role in the primary photochemistry but is required for the C-550 absorbance change.
用0.2%甲醇的己烷溶液提取Triton光系统II叶绿体片段3小时，可使原始制剂中90%至95%的质体醌被去除。提取后的片段（叶绿素：质体醌比率为900:1）在单次激光闪光后，于15K时未显示P-680光氧化现象。提取后的片段在77K时也未显示光诱导的C-550吸光度变化。通过添加质体醌A可恢复光系统II的初级反应，这可由P-680低温光氧化的恢复来证明，而添加β-胡萝卜素则不能。添加β-胡萝卜素加质体醌A可恢复C-550吸光度变化。这些结果表明，质体醌作为光系统II的初级电子受体起作用，β-胡萝卜素在初级光化学中不发挥直接作用，但对C-550吸光度变化是必需的。
