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Volume 148, 2011
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Channeling of electrons within SLAC, the small laccase from Streptomyces coelicolor

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Abstract

The reduction kinetics of the fluorescently labeled small laccase (SLAC) from Streptomyces coelicolor was studied by stopped flow kinetic measurements. The tryptophan fluorescence and the emission from a covalently attached label were used to selectively follow the progress of the reduction of the trinuclear copper center (TNC) and the type-1 (T1) Cu site in the enzyme as a function of time. A numerical analysis of the kinetic traces provided new insight into the midpoint potential difference between the T1 and the TNC site as the TNC becomes stepwise charged with electrons. The change in fluorescence of the TNC as the reduction of the TNC proceeds provided evidence that the type-3 dinuclear part of the TNC becomes charged prior to the reduction of the type-2 (T2) center of the TNC. The rate of reduction of the enzyme by dithionite (DT) appeared proportional to the square root of the DT concentration with a rate constant of kred = 0.28 ± 0.02 μM−1/2 s−1.

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Publication details

The article was received on 05 Feb 2010, accepted on 28 Apr 2010 and first published on 24 Sep 2010


Article type: Paper
DOI: 10.1039/C002585B
Citation: Faraday Discuss., 2011,148, 161-171
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    Channeling of electrons within SLAC, the small laccase from Streptomyces coelicolor

    A. W. J. W. Tepper, T. J. Aartsma and G. W. Canters, Faraday Discuss., 2011, 148, 161
    DOI: 10.1039/C002585B

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