Earlier
in vivo
studies showed the involvement of IspH protein in the conversion of 1-hydroxy-2-methyl-2-(
E
)-butenyl 4-diphosphate into isopentenyl diphosphate (IPP) and dimethylallyl diphosphate (DMAPP). We have demonstrated now that cell extract of an
Escherichia coli
strain engineered for hyperexpression of the
ispH
(
lytB
) gene catalyzes the
in vitro
conversion of 1-hydroxy-2-methyl-2-(
E
)-butenyl 4-diphosphate into IPP and DMAPP. The reaction requires NADH, FAD, divalent cations (preferably Co
2+
), and probably one or more as-yet-unidentified proteins. The low intrinsic catalytic activities of wild-type
E. coli
cell extract and isolated chromoplasts of red pepper (
Capsicum annuum
) are enhanced by the addition of purified recombinant IspH protein.
早期的体内研究表明IspH蛋白参与将1-羟基-2-甲基-2-(E)-丁烯基4-二磷酸转化为异戊二烯二磷酸(IPP)和二甲基烯丙基二磷酸(DMAPP)。我们现在证明,经过高表达ispH(lytB)基因的大肠杆菌工程菌株的细胞提取物可以在体外催化1-羟基-2-甲基-2-(E)-丁烯基4-二磷酸转化为IPP和DMAPP。该反应需要NADH、FAD、双价阳离子(最好是Co2+)和可能还需要一个或多个尚未鉴定的蛋白质。野生型大肠杆菌细胞提取物和红辣椒(Capsicum annuum)的分离色素体的内在催化活性通过添加纯化的重组IspH蛋白得到增强。