Department of Biological Sciences, Purdue University, West Lafayette, IN 47906, USA.
Photosynth Res. 2010 Mar;103(3):195-209. doi: 10.1007/s11120-010-9537-9. Epub 2010 Mar 9.
The discovery and the rediscovery of plastoquinone (PQ) are described together with the definition of its structure as a 2,3-dimethyl 5 solanosyl benzoquinone. The discovery, by M. Kofler, was a result of a search for Vitamin K. Its rediscovery was made by me, when I was at The Enzyme Institute of the University of Wisconsin, analyzing animals and plants for the newly discovered coenzyme Q. In green plants, I found another lipophilic quinone in addition to coenzyme Q. Some misleading evidence suggested as if the new quinone had coenzyme Q activity in mitochondria, but improved methods gave negative results. When I found that the quinone was concentrated in chloroplasts, I considered a role for it in photosynthesis analogous to the role of coenzyme Q in mitochondria. After moving to the Chemistry Department, University of Texas at Austin, I used a plain light bulb and some spinach chloroplasts to show that PQ could be involved in photosynthetic redox reactions. This effect was supported by Norman Bishop's restoration of chloroplast electron transport after solvent extraction, with PQ and photoreduction studies by E. R. Redfern and J. Friend in R. A. Morton's laboratory in Liverpool, UK. We also found an additional analog of PQ in addition to a second analog found in Wisconsin. We called the new analogs PQB and PQC. Although we found some restoration effects with PQC, the discovery by W. T. Griffiths in Morton's laboratory, that PQB and PQC consisted of six forms of PQ each, made it more likely that the new analogs were breakdown products. Morton's group established the structure of the PQCs as a series of PQs, with a hydroxyl group on the prenyl side chain, and the PQB series as having fatty acids esterified to the hydroxyl groups of PQC. Possible functions of the analogs are also discussed in this article.
本文描述了质体醌（PQ）的发现和重新发现过程，并将其结构定义为 2,3-二甲基 5 螺甾基苯醌。其发现者是 M. Kofler，他在寻找维生素 K 的过程中发现了质体醌。我在威斯康星大学的酶研究所重新发现了质体醌，当时我正在分析动物和植物中的新发现的辅酶 Q。在绿色植物中，除了辅酶 Q 之外，我还发现了另一种亲脂性醌。一些误导性的证据表明，这种新的醌在线粒体中具有辅酶 Q 的活性，但改进的方法得出了否定的结果。当我发现这种醌在叶绿体中浓缩时，我认为它在光合作用中的作用类似于辅酶 Q 在线粒体中的作用。搬到奥斯汀的德克萨斯大学化学系后，我使用普通灯泡和一些菠菜叶绿体来证明 PQ 可能参与光合作用中的氧化还原反应。这一效应得到了 Norman Bishop 的支持，他在溶剂提取后恢复了叶绿体电子传递，E. R. Redfern 和 J. Friend 在英国利物浦的 R. A. Morton 实验室进行了 PQ 的光还原研究。我们还在威斯康星州发现的第二种类似物之外，发现了另一种 PQ 的类似物。我们将新的类似物称为 PQB 和 PQC。尽管我们发现 PQC 具有一些恢复作用，但 W. T. Griffiths 在 Morton 实验室的发现表明，PQB 和 PQC 各由六种形式的 PQ 组成，这使得新类似物更有可能是分解产物。Morton 的小组确定了 PQC 的结构为一系列 PQ，在侧链的异戊烯基上有一个羟基，而 PQB 系列则是在 PQC 的羟基上酯化了脂肪酸。本文还讨论了类似物的可能功能。
