Key Laboratory of Chemical Biology of Natural Products, Ministry of Education, School of Pharmaceutical Sciences, Shandong University, Jinan 250012, China.
Key Laboratory of Chemical Biology of Natural Products, Ministry of Education, School of Pharmaceutical Sciences, Shandong University, Jinan 250012, China.
FEBS Lett. 2014 Jun 27;588(14):2307-14. doi: 10.1016/j.febslet.2014.05.023. Epub 2014 May 22.
FNS I is a 2-oxoglutarate dependent dioxygenase (2-ODD) found mainly in species of the Apiaceae family. Here, an FNS I cDNA sequence was isolated from the liverwort Plagiochasma appendiculatum (Aytoniaceae) and characterized. The recombinant protein exhibited high FNS I activity catalyzing the conversion of naringenin to apigenin and 2-hydroxynaringenin. The critical residue for flavanone-2-hydroxylation activity was Tyr240, as identified from homology modeling and site-directed mutagenesis. The recombinant protein also showed some flavonol synthase activity, as it can convert dihydrokaempferol to kaempferol. When the Leu311 residue was mutated to Phe, the enzyme's capacity to convert dihydrokaempferol to kaempferol was substantially increased. PaFNS I represents a 2-ODD in which a hydrophobic π-stacking interaction between the key residue and the naringenin A-ring determines 2-hydroxyflavanone formation.
FNS I 是一种 2-氧代戊二酸依赖性双加氧酶（2-ODD），主要存在于伞形科物种中。在这里，从叶苔科植物 Plagiochasma appendiculatum 中分离到 FNS I cDNA 序列并进行了表征。重组蛋白表现出较高的 FNS I 活性，可催化橙皮素转化为芹菜素和 2-羟基橙皮素。通过同源建模和定点突变确定 Tyr240 是黄酮酮-2-羟化活性的关键残基。重组蛋白还表现出一些黄酮醇合酶活性，因为它可以将二氢山奈酚转化为山奈酚。当 Leu311 残基突变为苯丙氨酸时，酶将二氢山奈酚转化为山奈酚的能力大大提高。PaFNS I 代表一种 2-ODD，其中关键残基与橙皮素 A 环之间的疏水 π-堆积相互作用决定了 2-羟基黄酮的形成。
