The role of threonine 37 in flavin reactivity of the old yellow enzyme
AUTOR(ES)
Xu, Dong
FONTE
The National Academy of Sciences
RESUMO
Threonine 37 is conserved among all the members of the old yellow enzyme (OYE) family. The hydroxyl group of this residue forms a hydrogen bond with the C-4 oxygen atom of the FMN reaction center of the enzyme [Fox, K. M. & Karplus, P. A. (1994) Structure 2, 1089–1105]. The position of Thr-37 and its interaction with flavin allow for speculations about its role in enzyme activity. This residue was mutated to alanine and the mutant enzyme was studied and compared with the wild-type OYE1 to evaluate its mechanistic function. The mutation has different effects on the two separate half-reactions of the enzyme. The mutant enzyme has enhanced activity in the oxidative half-reaction but the reductive half-reaction is slowed down by more than one order of magnitude. The peaks of the absorption spectra for enzyme bound with phenolic compounds are shifted toward shorter wavelengths than those of wild-type OYE1, consistent with its lower redox potential. It is suggested that Thr-37 in the wild-type OYE1 increases the redox potential of the enzyme by stabilizing the negative charge of the reduced flavin through hydrogen bonding with it.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=22332Documentos Relacionados
- Biotransformation of Explosives by the Old Yellow Enzyme Family of Flavoproteins
- Old Yellow Enzyme Protects the Actin Cytoskeleton from Oxidative Stress
- Old Yellow Enzyme: Stepwise reduction of nitro-olefins and catalysis of aci-nitro tautomerization
- Old yellow enzyme: Reduction of nitrate esters, glycerin trinitrate, and propylene 1,2-dinitrate
- Hold On to That Flavin♦: Structural and Mechanistic Studies Reveal the Functional Role of Bicovalent Flavinylation in Berberine Bridge Enzyme