Structural Characterization of the Copper Site in Galactose Oxidase Using X-ray Absorption Spectroscopy

Kimber Clark, James E. Penner-Hahn, Mei Whittaker, James W. Whittaker

Research output: Contribution to journalArticle

42 Scopus citations

Abstract

X-ray absorption spectroscopy has been used to characterize the local structural environment of the Cu ion in the reductively inactivated, oxidatively activated, and active+substrate oxidation state derivatives of galactose oxidase. In all three cases, the local environment of the Cu is best modeled by a single shell of low-Z (N or O) scatterers. This is generally consistent with the structure determined crystallographically, although the EXAFS bond lengths are slightly, but significantly, shorter than those found crystallographically. The best-fit average bond lengths are 1.97, 1.95, and 1.98 Å for inactive, active, and active+substrate, respectively. The CuII ion in the active and inactive derivatives has an apparent coordination number of 4, consistent with the equatorial ligation seen crystallographically. The CuI ion in the reduced+substrate derivative appears to have either a lower coordination number or a significantly more distorted local environment. The observed CuI-N/O) bond length favors a model where the Cu becomes 3-coordinate in the substrate-reduced complex.

Original languageEnglish (US)
Pages (from-to)12553-12557
Number of pages5
JournalBiochemistry
Volume33
Issue number42
DOIs
StatePublished - Oct 1 1994

ASJC Scopus subject areas

  • Biochemistry

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