期刊
BIOORGANIC & MEDICINAL CHEMISTRY
卷 14, 期 19, 页码 6555-6559出版社
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.bmc.2006.06.011
关键词
type 2 isopentenyl diphosphate isomerase; reaction mechanism; archaea; inhibitor
Type 2 isopentenyl diphosphate:dimethylallyl diphosphate isomerase (IDI-2, EC 5.3.3.2) is a flavoprotein, which requires FMN, NADPH, and Mg2+ for the activity to convert isopentenyl diphosphate to dimethylallyl diphosphate. For investigation of the reaction mechanism of IDI-2, 3,4-epoxy-3-methylbutyl diphosphate (EIPP), a mechanism-based inhibitor of type 1 IDI (IDI-1), was treated with the overexpressed IDI-2 (MjIDI) from methanogenic archaeon Methanocaldococcus jannaschii. EIPP showed the time- and concentration-dependent inhibition (K-I; 56.5 mM, k(inact); 0.10 s(-1), k(inact)/K-I; 1.76 s(-1) M-1) and the UV-vis spectrum of MjIDI after treatment with EIPP was apparently different from that of the untreated MjIDI. These results indicated that EIPP modified FMN through a covalent bond in the active site of MjIDI. The formed EIPP-FMN complex was separated from the reaction mixture and the spectrometric analysis of the complex suggested that the reduced form of FMN bound to EIPP at the N5 position. These results may suggest that the IDI-2 reaction is similar to IDI-1, which proceeds via carbocation-type intermediate. (c) 2006 Elsevier Ltd. All rights reserved.
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