Quercetin 2,4-Dioxygenase Activates Dioxygen in a Side-On O2-Ni Complex.
Angew Chem Int Ed Engl
; 55(10): 3281-4, 2016 Mar 01.
Article
en En
| MEDLINE
| ID: mdl-26846734
ABSTRACT
Quercetin 2,4-dioxygenase (quercetinase) from Streptomyces uses nickel as the active-site cofactor to catalyze oxidative cleavage of the flavonol quercetin. How this unusual active-site metal supports catalysis and O2 activation is under debate. We present crystal structures of Ni-quercetinase in three different states, thus providing direct insight into how quercetin and O2 are activated at the Ni(2+) ion. The Ni(2+) ion is coordinated by three histidine residues and a glutamate residue (E(76)) in all three states. Upon binding, quercetin replaces one water ligand at Ni and is stabilized by a short hydrogen bond through E(76) , the carboxylate group of which rotates by 90°. This conformational change weakens the interaction between Ni and the remaining water ligand, thereby preparing a coordination site at Ni to bind O2. O2 binds side-on to the Ni(2+) ion and is perpendicular to the C2-C3 and C3-C4 bonds of quercetin, which are cleaved in the following reaction steps.
Palabras clave
Texto completo:
1
Bases de datos:
MEDLINE
Asunto principal:
Oxígeno
/
Proteínas Bacterianas
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Dioxigenasas
/
Níquel
Idioma:
En
Revista:
Angew Chem Int Ed Engl
Año:
2016
Tipo del documento:
Article
País de afiliación:
Alemania