Electronic Characterization of the Oxidized State of the Blue Copper Protein Rusticyanin by 1H NMR: Is the Axial Methionine the Dominant Influence for the High Redox Potential?

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• 作者：Antonio Donaire ; Beatriz Jimé ; nez ; José ; -Marí ; a Moratal ; John F. Hall ; and S. Samar Hasnain
• 刊名：Biochemistry
• 出版年：2001
• 出版时间：January 23, 2001
• 年：2001
• 卷：40
• 期：3
• 页码：837 - 846
• 全文大小：114K
• 年卷期：v.40,no.3(January 23, 2001)
• ISSN：1520-4995

文摘

The oxidized state of rusticyanin, the blue copper protein with the highest redox potential inits class, has been investigated through ¹H nuclear magnetic resonance applied to its cobalt(II) derivative.The assignment of the protons belonging to the coordinated residues has been performed. Many otheramino acids situated in the vicinity of the metal ion, including six hydrophobic residues (isoleucine140and five phenylalanines) have also been identified. The orientation of the main axes of the magneticsusceptibility tensor for the cobalt(II)-rusticyanin as well as its axial, _ax, and rhombic, _rh, magneticsusceptibility anisotropy components have been determined. A comparison of the present results withthose previously obtained for cobalt(II)azurin [Donaire, A., Salgado, J., Moratal, J. M. (1998) Biochemistry37, 8659-8673] allows us to provide further insights into the reasons for the high redox potential of thisprotein. According to our results, the interaction between the metal ion and the thioether S of the axialmethionine is not as influential as the strong destabilizing effect that the hydrophobic residues close tothe metal ion undergo in the oxidized state.