R. Moore, Spies, M. Culpepper
Aug 23, 2007
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0
Influential Citations
15
Citations
Journal
Journal of the American Chemical Society
Abstract
The biogenesis of the topaquinone (TPQ) cofactor of copper amine oxidase (CAO) is self-catalyzed and requires copper and molecular oxygen. A dopaquinone intermediate has been proposed to undergo 1,4-addition of a copper-associated water molecule to form the reduced form of TPQ (TPQred), followed by facile oxidation by O2 to yield the mature TPQ (TPQox). In this study, we have incorporated a lysine residue in the active site of Arthrobacter globiformis CAO (AGAO) by site-directed mutagenesis to produce D298K-AGAO. The X-ray crystal structure of D298K-AGAO at 1.7-A resolution revealed that a covalent linkage formed between the e-amino side chain of Lys298 and the C2 position of a dopaquinone derived from Tyr382, a precursor to TPQox. We assigned the species as an iminoquinone tautomer (LTI) of lysine tyrosylquinone (LTQ), the organic cofactor of lysyl oxidase (LOX). The time course of the formation of LTI at pH 6.8 was followed by UV/vis and resonance Raman spectroscopies. In the early phase of the reaction...