Threlfall D R, Griffiths W T, Goodwin T W
Biochem J. 1967 Jun;103(3):831-51. doi: 10.1042/bj1030831.
The incorporation of (14)C by etiolated maize and barley shoots exposed to light of (14)CO(2) and [2-(14)C]mevalonic acid into phylloquinone, plastoquinone, ubiquinone, alpha-tocopherolquinone and alpha-tocopherol was examined. In maize (the principal tissue studied) it was demonstrated that (14)C from [2-(14)C]mevalonic acid is incorporated into phylloquinone, plastoquinone and ubiquinone. alpha-Tocopherol and alpha-tocopherolquinone, although undoubtedly labelled from this substrate, were not purified completely. As expected, (14)C from (14)CO(2) was incorporated into all components examined. Ozonolytic degradation studies showed that (14)C from [2-(14)C]mevalonic acid was incorporated specifically into the prenyl side chains of plastoquinone and ubiquinone, and from this it was inferred that mevalonic acid can be regarded as the specific distal precursor to the prenyl portions of all terpenoid quinones occurring in plant tissues. From a comparison of the relative incorporation of (14)C from (14)CO(2) and [2-(14)C]mevalonic acid into the intra- and extra-chloroplastidic terpenoids evidence was obtained consistent with the tenet that the prenyl portions of the chloroplastidic quinones phylloquinone and plastoquinone, along with beta-carotene, are biosynthesized within the confines of the chloroplast, the side chain of the extraplastidic ubiquinone and phytosterols being synthesized elsewhere within the cell. The results obtained for the incorporation of (14)C from (14)CO(2) and [2-(14)C]mevalonic acid into alpha-tocopherol and alpha-tocopherolquinone were not readily interpretable with regard to the site of synthesis of these compounds.
研究了黄化玉米和大麦幼苗在暴露于(^{14}CO_2)和([2-^{14}C])甲羟戊酸的光照下，(^{14}C)掺入叶醌、质体醌、泛醌、α-生育酚醌和α-生育酚的情况。在玉米（主要研究的组织）中，已证明来自([2-^{14}C])甲羟戊酸的(^{14}C)掺入叶醌、质体醌和泛醌中。α-生育酚和α-生育酚醌虽然无疑也由该底物标记，但未完全纯化。正如预期的那样，来自(^{14}CO_2)的(^{14}C)掺入了所有检测的成分中。臭氧分解降解研究表明，来自([2-^{14}C])甲羟戊酸的(^{14}C)特异性地掺入质体醌和泛醌的异戊烯侧链中，据此推断甲羟戊酸可被视为植物组织中所有萜类醌的异戊烯部分的特定远端前体。通过比较来自(^{14}CO_2)和([2-^{14}C])甲羟戊酸的(^{14}C)相对掺入叶绿体和叶绿体外部萜类化合物的情况，获得的证据与以下原则一致：叶绿体醌叶醌和质体醌的异戊烯部分以及β-胡萝卜素在叶绿体内合成，叶绿体外部泛醌和植物甾醇的侧链在细胞内的其他地方合成。关于这些化合物的合成位点，从(^{14}CO_2)和([2-^{14}C])甲羟戊酸的(^{14}C)掺入α-生育酚和α-生育酚醌的结果不易解释。
