Hirooka K, Kato T, Matsu-ura J, Hemmi H, Nishino T
Department of Biochemistry and Engineering, Tohoku University, Aoba Aramaki 07, Aoba-ku, Sendai 980-8579, Japan.
FEBS Lett. 2000 Sep 8;481(1):68-72. doi: 10.1016/s0014-5793(00)01972-4.
Sulfolobus acidocaldarius geranylgeranyl diphosphate synthase yields (all-E)-C(20) prenyl diphosphate as a final product. The three-dimensional model of the enzyme suggested that removing two bulky residues at 77 and 114 would allow additional prenyl-chain elongation. To test this, we examined several mutants with substitutions at 77 and/or 114. As a result, the mutants, F77G, F77G and H114A, F77G and H114G, H114A, and H114G gave C(30), C(45), C(50), C(30) and C(40) as the main long product, respectively. These observations indicate that histidine-114 plays a crucial role in chain-length determination along with phenylalanine-77.
嗜酸热硫化叶菌香叶基香叶基二磷酸合酶产生（全 - E）-C₂₀ 异戊二烯基二磷酸作为最终产物。该酶的三维模型表明，去除 77 位和 114 位的两个大体积残基将允许额外的异戊二烯链延长。为了验证这一点，我们检测了几个在 77 位和/或 114 位有替换的突变体。结果，突变体 F77G、F77G 和 H114A、F77G 和 H114G、H114A 以及 H114G 分别产生 C₃₀、C₄₅、C₅₀、C₃₀ 和 C₄₀ 作为主要的长链产物。这些观察结果表明，组氨酸 - 114 与苯丙氨酸 - 77 一起在链长确定中起关键作用。
