| Autor: |
Ravichandran KR, Zong AB; Department of Biochemistry and Biophysics, University of Pennsylvania Perelman School of Medicine , Philadelphia, Pennsylvania 19104, United States., Taguchi AT, Nocera DG; Department of Chemistry and Chemical Biology, Harvard University , 12 Oxford Street, Cambridge, Massachusetts 02138, United States., Stubbe J, Tommos C; Department of Biochemistry and Biophysics, University of Pennsylvania Perelman School of Medicine , Philadelphia, Pennsylvania 19104, United States. |
| Jazyk: |
angličtina |
| Zdroj: |
Journal of the American Chemical Society [J Am Chem Soc] 2017 Mar 01; Vol. 139 (8), pp. 2994-3004. Date of Electronic Publication: 2017 Feb 21. |
| DOI: |
10.1021/jacs.6b11011 |
| Abstrakt: |
Redox-active tyrosines (Ys) play essential roles in enzymes involved in primary metabolism including energy transduction and deoxynucleotide production catalyzed by ribonucleotide reductases (RNRs). Thermodynamic characterization of Ys in solution and in proteins remains a challenge due to the high reduction potentials involved and the reactive nature of the radical state. The structurally characterized α 3 Y model protein has allowed the first determination of formal reduction potentials (E°') for a Y residing within a protein (Berry, B. W.; Martı́nez-Rivera, M. C.; Tommos, C. Proc. Natl. Acad. Sci. U. S. A. 2012, 109, 9739-9743). Using Schultz's technology, a series of fluorotyrosines (F n Y, n = 2 or 3) was site-specifically incorporated into α 3 Y. The global protein properties of the resulting α 3 (3,5)F 2 Y, α 3 (2,3,5)F 3 Y, α 3 (2,3)F 2 Y and α 3 (2,3,6)F 3 Y variants are essentially identical to those of α 3 Y. A protein film square-wave voltammetry approach was developed to successfully obtain reversible voltammograms and E°'s of the very high-potential α 3 F n Y proteins. E°'(pH 5.5; α 3 F n Y(O•/OH)) spans a range of 1040 ± 3 mV to 1200 ± 3 mV versus the normal hydrogen electrode. This is comparable to the potentials of the most oxidizing redox cofactors in nature. The F n Y analogues, and the ability to site-specifically incorporate them into any protein of interest, provide new tools for mechanistic studies on redox-active Ys in proteins and on functional and aberrant hole-transfer reactions in metallo-enzymes. The former application is illustrated here by using the determined α 3 F n Y ΔE°'s to model the thermodynamics of radical-transfer reactions in F n Y-RNRs and to experimentally test and support the key prediction made. |
| Databáze: |
MEDLINE |
| Externí odkaz: |
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