Design of a single protein that spans the entire 2-V range of physiological redox potentials

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 113; no. 2; pp. 262 - 267
• Main Authors: Hosseinzadeh, Parisa, Marshall, Nicholas M., Chacón, Kelly N., Yu, Yang, Nilges, Mark J., New, Siu Yee, Tashkov, Stoyan A., Blackburn, Ninian J., Lu, Yi
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences 12.01.2016; National Acad Sciences
• Series: From the Cover
• Subjects: Azurin - chemistry; Azurin - metabolism; Bacterial proteins; Biochemistry; Biophysics; Biotechnology; Electrochemical Techniques; Electron Spin Resonance Spectroscopy; Gram-positive bacteria; Models, Molecular; Mutation - genetics; Oxidation-Reduction; Physical Sciences; Physiology; Protein Engineering; Spectrometry, X-Ray Emission; Spectrophotometry, Ultraviolet; Spectrum analysis; secondary coordination sphere; cupredoxins; electron transfer; reduction potential; azurin
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.1515897112

The reduction potential (Eo′) is a critical parameter in determining the efficiency of most biological and chemical reactions. Biology employs three classes of metalloproteins to cover the majority of the 2-V range of physiological Eo′s. An ultimate test of our understanding of Eo′ is to find out the minimal number of proteins and their variants that can cover this entire range and the structural features responsible for the extreme Eo′. We report herein the design of the protein azurin to cover a range from +970 mV to −954 mV vs. standard hydrogen electrode (SHE) by mutating only five residues and using two metal ions. Spectroscopic methods have revealed geometric parameters important for the high Eo′. The knowledge gained and the resulting water-soluble redox agents with predictable Eo′s, in the same scaffold with the same surface properties, will find wide applications in chemical, biochemical, biophysical, and biotechnological fields.