Metalloproteins Diversified: The Auracyanins Are a Family of Cupredoxins That Stretch the Spectral and Redox Limits of Blue Copper Proteins

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• 作者：Jeremy D. King ; Chelsea L. McIntosh ; Christopher M. Halsey ; Bryan M. Lada ; Dariusz M. Niedzwiedzki ; Jason W. Cooley ; Robert E. Blankenship
• 刊名：Biochemistry
• 出版年：2013
• 出版时间：November 19, 2013
• 年：2013
• 卷：52
• 期：46
• 页码：8267-8275
• 全文大小：540K
• 年卷期：v.52,no.46(November 19, 2013)
• ISSN：1520-4995

文摘

The metal sites of electron transfer proteins are tuned for function. The type 1 copper site is one of the most utilized metal sites in electron transfer reactions. This site can be tuned by the protein environment from +80 mV to +680 mV in typical type 1 sites. Accompanying this huge variation in midpoint potentials are large changes in electronic structure, resulting in proteins that are blue, green, or even red. Here, we report a family of blue copper proteins, the auracyanins, from the filamentous anoxygenic phototroph Chloroflexus aurantiacus that display the entire known spectral and redox variations known in the type 1 copper site. C. aurantiacus encodes four auracyanins, labeled A鈥揇. The midpoint potentials vary from +83 mV (auracyanin D) to +423 mV (auracyanin C). The electronic structures vary from classical blue copper UV鈥搗is absorption spectra (auracyanin B) to highly perturbed spectra (auracyanins C and D). The spectrum of auracyanin C is temperature-dependent. The expansion and divergent nature of the auracyanins is a previously unseen phenomenon.