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Spectroscopic and crystallographic characterization of "alternative resting" and "resting oxidized" enzyme forms of bilirubin oxidase: implications for activity and electrochemical behavior of multicopper oxidases.

ABSTRACT: While there is broad agreement on the catalytic mechanism of multicopper oxidases (MCOs), the geometric and electronic structures of the resting trinuclear Cu cluster have been variable, and their relevance to catalysis has been debated. Here, we present a spectroscopic characterization, complemented by crystallographic data, of two resting forms occurring in the same enzyme and define their interconversion. The resting oxidized form shows similar features to the resting form in Rhus vernicifera and Trametes versicolor laccase, characterized by "normal" type 2 Cu electron paramagnetic resonance (EPR) features, 330 nm absorption shoulder, and a short type 3 (T3) Cu-Cu distance, while the alternative resting form shows unusually small A(||) and high g(||) EPR features, lack of 330 nm absorption intensity, and a long T3 Cu-Cu distance. These different forms are evaluated with respect to activation for catalysis, and it is shown that the alternative resting form can only be activated by low-potential reduction, in contrast to the resting oxidized form which is activated via type 1 Cu at high potential. This difference in activity is correlated to differences in redox states of the two forms and highlights the requirement for efficient sequential reduction of resting MCOs for their involvement in catalysis.

SUBMITTER: Kjaergaard CH

PROVIDER: S-EPMC3339634 | biostudies-literature | 2012 Mar

REPOSITORIES: biostudies-literature

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Spectroscopic and crystallographic characterization of "alternative resting" and "resting oxidized" enzyme forms of bilirubin oxidase: implications for activity and electrochemical behavior of multicopper oxidases.

Kjaergaard Christian H CH Durand Fabien F Tasca Federico F Qayyum Munzarin F MF Kauffmann Brice B Gounel Sébastien S Suraniti Emmanuel E Hodgson Keith O KO Hedman Britt B Mano Nicolas N Solomon Edward I EI

Journal of the American Chemical Society 20120321 12

While there is broad agreement on the catalytic mechanism of multicopper oxidases (MCOs), the geometric and electronic structures of the resting trinuclear Cu cluster have been variable, and their relevance to catalysis has been debated. Here, we present a spectroscopic characterization, complemented by crystallographic data, of two resting forms occurring in the same enzyme and define their interconversion. The resting oxidized form shows similar features to the resting form in Rhus vernicifera ...[more]

PMID: 22413777

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Dataset Information

Spectroscopic and crystallographic characterization of "alternative resting" and "resting oxidized" enzyme forms of bilirubin oxidase: implications for activity and electrochemical behavior of multicopper oxidases.

Publications

Spectroscopic and crystallographic characterization of "alternative resting" and "resting oxidized" enzyme forms of bilirubin oxidase: implications for activity and electrochemical behavior of multicopper oxidases.

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