Institut für Biologie II, Lehrstuhl für Genetik der Universität, Auf der Morgenstelle 28, D-7400, Tübingen, Federal Republic of Germany.
Planta. 1984 May;161(3):261-5. doi: 10.1007/BF00982923.
Precursor experiments and chromatographic studies indicate that the hydroxylation of flavanones in the 3-position to dihydroflavonols is blocked in special white-flowering mutants ofDahlia, Streptocarpus, Verbena andZinnia. The result of our investigations was confirmed in as much as the activity of the enzyme flavanone 3-hydroxylase, which catalyses the conversion of flavanones to dihydroflavonols, could readily be detected in flower extracts of cyanic strains of the four plant species. It was found to be, however, completely absent in flower extracts of the corresponding acyanic mutants. Thus, the interruption of the anthocyanin pathway in these mutants is clearly caused by a lack of this enzyme activity. Similar to the enzymes from other sources, the 3-hydroxylases ofDahlia, Streptocarpus, Verbena andZinnia are soluble enzymes; they belong to the 2-oxoglutarate-dependent dioxygenases and the reaction is inhibited by ethylenediaminetetraacetic acid, KCN and diethyldithiocarbamate.
前体实验和色谱研究表明，在大丽花、扭萼花属、马鞭草属和百日草的特殊白花突变体中，黄酮类化合物在 3-位的羟化作用被阻断。我们的研究结果得到了证实，因为催化黄酮类化合物转化为二氢黄酮醇的黄酮醇 3-羟化酶的活性在这四个植物物种的氰化物菌株的花提取物中很容易被检测到。然而，在相应的非氰化物突变体的花提取物中，这种酶的活性完全缺失。因此，这些突变体中花青素途径的中断显然是由于缺乏这种酶活性引起的。与其他来源的酶相似，大丽花、扭萼花属、马鞭草属和百日草的 3-羟化酶是可溶性酶；它们属于 2-氧戊二酸依赖性加氧酶，反应被乙二胺四乙酸、氰化钾和二乙基二硫代氨基甲酸盐抑制。
