Kinetic and spectroscopic characterization of type II isopentenyl diphosphate isomerase from Thermus thermophilus: evidence for formation of substrate-induced flavin species.

ABSTRACT: Type II isopentenyl diphosphate (IPP) isomerase catalyzes the interconversion of IPP and dimethylallyl diphosphate (DMAPP). Although the reactions catalyzed by the type II enzyme and the well-studied type I IPP isomerase are identical, the type II protein requires reduced flavin for activity. The chemical mechanism, including the role of flavin, has not been established for type II IPP isomerase. Recombinant type II IPP isomerase from Thermus thermophilus HB27 was purified by Ni2+ affinity chromatography. The aerobically purified enzyme was inactive until the flavin cofactor was reduced by NADPH or dithionite or photochemically. The inactive oxidized flavin-enzyme complex bound IPP in a Mg2+-dependent manner for which KD approximately KmIPP, suggesting that the substrate binds to the inact

SUBMITTER: Rothman SC 

PROVIDER: S-EPMC2516918 | biostudies-literature | 2007 May

REPOSITORIES: biostudies-literature