Models for the redox active site in galactose oxidase

Mei M. Whittaker, Yao Yuan Chuang, James Whittaker

Research output: Contribution to journalArticle

102 Citations (Scopus)

Abstract

Modeling approaches have been used to develop insight into the nature of the redox active site of the free-radical-containing copper metalloenzyme galactose oxidase. The optical spectrum of the free radical generated by low-temperature UV irradiation of (methylthio)cresol is nearly identical to that observed for the free-radical site in metal-free apo galactose oxidase, supporting the assignment of the protein radical to a novel tyrosine-cysteine covalent cross-link structure recently reported from X-ray crystallographic studies. Basic characterization of the chemistry for this new type of biological redox group includes measurements of the substituent effects on phenolic proton acidic and observation of the oxygenation of (methylthio)cresol with peroxides. The latter reaction models a possible inactivation pathway for the enzyme. Low-temperature absorption and EPR spectra were obtained for free radicals formed from the methylthio and methylsulfinyl derivatives that are most important as models for the biological active site for comparison with the parent cresol radical. A series of simple copper complexes has been prepared with cresol, (methylthio) cresol, and (methylsulfinyl)cresol ligands to explore the effect of substitution on coordination chemistry. Structural and spectroscopic data obtained for these inorganic models contribute to an understanding of the active site metal interactions, providing evidence that the thio ether sulfur of the protein redox group is noncoordinating in the crystallographically defined enzyme complex.

Original languageEnglish (US)
Pages (from-to)10029-10035
Number of pages7
JournalJournal of the American Chemical Society
Volume115
Issue number22
StatePublished - 1993
Externally publishedYes

Fingerprint

cresol
Galactose Oxidase
Free radicals
Oxidation-Reduction
Catalytic Domain
Free Radicals
Enzymes
Proteins
Copper
Oxygenation
Peroxides
Metals
Telecommunication links
Paramagnetic resonance
Biological Models
Protons
Temperature
Substitution reactions
Ligands
Irradiation

ASJC Scopus subject areas

  • Chemistry(all)

Cite this

Whittaker, M. M., Chuang, Y. Y., & Whittaker, J. (1993). Models for the redox active site in galactose oxidase. Journal of the American Chemical Society, 115(22), 10029-10035.

Models for the redox active site in galactose oxidase. / Whittaker, Mei M.; Chuang, Yao Yuan; Whittaker, James.

In: Journal of the American Chemical Society, Vol. 115, No. 22, 1993, p. 10029-10035.

Research output: Contribution to journalArticle

Whittaker, MM, Chuang, YY & Whittaker, J 1993, 'Models for the redox active site in galactose oxidase', Journal of the American Chemical Society, vol. 115, no. 22, pp. 10029-10035.
Whittaker MM, Chuang YY, Whittaker J. Models for the redox active site in galactose oxidase. Journal of the American Chemical Society. 1993;115(22):10029-10035.
Whittaker, Mei M. ; Chuang, Yao Yuan ; Whittaker, James. / Models for the redox active site in galactose oxidase. In: Journal of the American Chemical Society. 1993 ; Vol. 115, No. 22. pp. 10029-10035.
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