47(P-11) ウンデカプレニル二リン酸合成酵素の基質特異性(2)(ポスター発表の部)

概要

論文の詳細を見る
Undecaprenyl diphosphate synthase (UPS) catalyzes the condensation of isopentenyl diphophate (IPP) with E,E-farnesyl diphosphate (FPP) to yield undecaprenyl diphosphate (UPP) with E, Z mixed stereochemistry. UPS is classified as one of Z-type prenyltransferases. The comparison of animo acid sequnces of this enzyme with E-prenyltransferases revealed that UPS does not have any similar conserved regions found in E-type prenyltrasferases. The comparison of substrate specificity of this enzyme is of very interest. We have studied the substrate specificity of UPS from Micrococcus luteus B-P 20 using a number of substrate analogs 1-21 and compared with those of farnesyl diphosphate synthase (FPS). The analogs 1-5,17,18,20 and 21, which have similar structural features to that of FPP showed the high enzymatic activities. Especially, the analog 5 having just same chain length as one of FPP, showed the highest reactivity among the analogs tested here. The analogs with shoter or longer chain than one of 5 showed less rectivities. These results indicated that the chain length of substrate is very important. On the other hand, the analogs 6-12, which have oxygen atom in their side chain showed less reactivity. Among the low reactive analogs studied here, the analogs 14, 15 and 1 9, which have no 3-methyl group of the allylic diphosphates, GPP, FPP and GGPP respectively, showed the inhibitory effects to UPS. The same effects were observed in BST-FPS reaction. The findings suggested that UPS reaction proceeds through the "ionization-condensation-elimination" mechanism just found in the FPS reaction. The 3-methyl group of allylic substrates is proved to be crucial due to the size and the electronic effect. The analyses of products were carried out by using the reversed phase thin layer chromatography (LKC-18). The products were identified by comparing the Rf values with one of UPP. The results implied that the anlogs 1,3,4,5,17, and 21 give the similar products as UPP, respectively. In summary, UPS from Micrococcus luteus B-P 20 is shown to be more stringent than that of FPS. Namely UPS can hardly accept the analogs having oxygen atom in their chain and 3-desmethyl allylic analogs are the effective inhibitors for UPS. The latter finding strongly indicates that the methyl group at 3-position of allylic is very important for the substrate recognition of UPS.
天然有機化合物討論会の論文
2000-10-01

47(P-11) ウンデカプレニル二リン酸合成酵素の基質特異性(2)(ポスター発表の部)

スポンサーリンク

概要

著者

関連論文

スポンサーリンク