Frerichs-Deeken_2005_Curr.Microbiol_51_344

Reference

Title : Dioxygenases without requirement for cofactors: identification of amino acid residues involved in substrate binding and catalysis, and testing for rate-limiting steps in the reaction of 1H-3-hydroxy-4-oxoquinaldine 2,4-dioxygenase - Frerichs-Deeken_2005_Curr.Microbiol_51_344
Author(s) : Frerichs-Deeken U , Fetzner S
Ref : Curr Microbiol , 51 :344 , 2005
Abstract :

1H-3-Hydroxy-4-oxoquinaldine 2,4-dioxygenase (Hod), catalyzing cleavage of its heteroaromatic substrate to form carbon monoxide and N-acetylanthranilate, belongs to the alpha/beta hydrolase fold family of enzymes. Analysis of protein variants suggested that Hod has adapted active-site residues of the alpha/beta hydrolase fold for the dioxygenolytic reaction. H251 was recently shown to act as a general base to abstract a proton from the organic substrate. Residue S101, which corresponds to the nucleophile of the catalytic triad of alpha/beta-hydrolases, presumably participates in binding the heteroaromatic substrate. H102 and residues located in the topological region of the triad's acidic residue appear to influence O2 binding and reactivity. A tyrosine residue might be involved in the turnover of the ternary complex [HodH+-3,4-dioxyquinaldine dianion-O2]. Absence of viscosity effects and kinetic solvent isotope effects suggests that turnover of the ternary complex, rather than substrate binding, product release, or proton movements, involves the rate-determining step in the reaction catalyzed by Hod.

PubMedSearch : Frerichs-Deeken_2005_Curr.Microbiol_51_344
PubMedID: 16187153
Gene_locus related to this paper: artsp-hod

Citations formats

Frerichs-Deeken U, Fetzner S (2005)
Dioxygenases without requirement for cofactors: identification of amino acid residues involved in substrate binding and catalysis, and testing for rate-limiting steps in the reaction of 1H-3-hydroxy-4-oxoquinaldine 2,4-dioxygenase
Curr Microbiol 51 :344

Frerichs-Deeken U, Fetzner S (2005)
Curr Microbiol 51 :344