Catalytic mechanism of type 2 isopentenyl diphosphate:dimethylallyl diphosphate isomerase: verification of a redox role of the flavin cofactor in a reaction with no net redox change.
Type 2 isopentenyl diphosphate:dimethylallyl diphosphate isomerase requires redox co-enzymes, i.e., flavin mononucleotide (FMN) and NAD(P)H, for activity, although it catalyzes a non-redox reaction. Spectrometric studies and enzyme assays under anaerobic conditions indicate that FMN is reduced through the reaction and is sufficient for activity. The sole function of NAD(P)H appears to be the reduction of FMN since it could be replaced by an alternate reducing agent. When the enzyme was reconstructed with a flavin analogue, no activity was detected, suggesting that the isomerase reaction proceeds via a radical transfer mechanism.
Hemmi
Hisashi
H
Department of Biomolecular Engineering, Graduate School of Engineering, Tohoku University, Aoba-yama 07, Sendai, Miyagi 980-8579, Japan. hhemmi@seika.che.tohoku.ac.jp
Ikeda
Yosuke
Y
Yamashita
Satoshi
S
Nakayama
Toru
T
Nishino
Tokuzo
T
D019748:Carbon-Carbon Double Bond Isomerases / Q000378:metabolism*; D002384:Catalysis; D004227:Dithionite / Q000494:pharmacology; D005486:Flavin Mononucleotide / Q000378:metabolism; D005415:Flavins / Q000378:metabolism; D045782:Hemiterpenes; D007700:Kinetics; D009243:NAD / Q000378:metabolism; D009249:NADP / Q000378:metabolism; D010084:Oxidation-Reduction; D013053:Spectrophotometry
D005415:Flavins; D045782:Hemiterpenes; D009243:NAD; D004227:Dithionite; D009249:NADP; D005486:Flavin Mononucleotide; D019748:Carbon-Carbon Double Bond Isomerases; C021453:isopentenyldiphosphate delta-isomerase