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Abstract
Heme copper oxidase (HCO), which can reduce oxygen to water, is an indispensable substance in bioenergy production. The large molecular weight, difficult expression and spectral study of HCO are the bottlenecks restricting its mechanical research and application.
Through the genetic incorporation of the Tyr-His ligand and CuB site into myoglobin, we recapitulated important features of HCO into this small soluble protein, which exhibits selective O2 reduction activity while generating less than 6% ROS, at more than 1000 turnovers. These results support that Tyr-His crosslink is indeed important for HCO function, and creates the exciting opportunity to rapidly evolve better HCO model proteins to achieve higher activity and selectivity, which may be suitable as alternatives to precious metal catalyst in fuel cells.
By engineering more favorable electrostatic interactions between a functional oxidase model designed in sperm whale myoglobin and its native redox partner, cyt b5, resulting in a 400-fold electron transfer (ET) rate enhancement, with an O2 reduction rate (52 s-1) comparable to that of a native cytochrome (cyt) cbb3 oxidase (50 s-1) under identical conditions. Achieving high activity equivalent to that of native enzymes in a designed metalloenzyme offers deeper insight into the roles of tunable processes such as ET in oxidase activity and enzymatic function and may extend into applications such as more efficient oxygen reduction reaction catalysts for biofuel cells.
Recently, based on our previous works, with genetic encode technology, we have developed a photosensitizer protein (PSP) by incorporating an unnatural amino acid (Bpa) containing a benzophenone side chain into chromophore of fluorescent protein. When ligated with a CO2 reduction catalyst, the PSP can be used as a photoredox catalyst for CO2 reduction. Compare with small photoredox molecules, the photoredox protein has the following additional merits:
1. heavy-metal free; 2. can be easily introduced into various organisms; 3. having dramatically expanded abilities through rational design or directed evolution. |
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Biography
Xiaohong LIU/刘晓红
e-mail: liuxh@moon.ibp.ac.cn
http://www.ibp.cas.cn/kydw/ibpqchhy/201312/t20131216_3999517.html
The main interest is to design metalloenzymes that are easy to characterize, produce and optimize by using small, soluble protein scaffolds and genetic incorporation of non-natural amino acids. These metalloenzymes catalyze important reactions with efficiency/selectivity equal to or higher than natural systems.
Education-
Ph.D., Sep. 2002-Jul. 2005, Department of Chemistry, Tsinghua university, Organic Chemistry
M.S., Sep. 1999-Jul. 2002, Chemistry and Life Science College, Tianjin Normal University, Physical Chemistry
B.S., Sep. 1995-Jul. 1999, Chemistry and Life Science College, Tianjin Normal University, Physical Chemistry
Work Experience-
Jan.2015-Pre. Professor, Institute of Biophysics, CAS
Jan.2012-Dec.2014 Associate professor, Institute of Biophysics, CAS
May.2008-Dec.2011 Assistance Professor, Institute of Biophysics, CAS
Aug.2005-Mar.2008 Postdoctoral Fellow, Teikyo University of Science and Technology, Yamanashi Prefecture, Japan
Representative Publicaitions-
1) X.H. Liu, F.Y. Kang, C. Hu, L. Wang, Z Xu, D.D Zheng, J. Huang, Y. Lu, P.G. Schultz, J.Y. Wang. A genetically encoded photosensitizer protein facilitates the rational design of a miniature photocatalytic CO2 reducing enzyme. Nature Chemistry (2018) 10, 1201–1206.
2) Y. Yu1, C Cui1, X.H. Liu1, I. D. Petrik, J.Y. Wang, and Y. Lu. A Designed Metalloenzyme Achieving the Catalytic Rate of a Native Enzyme. Journal of the American Chemical Society, (2015) 137 (36), 11570–11573
3) X.H. Liu1, L Jiang1, J Li1, L Wang, Y Yu, Q Zhou, X Lv, W Gong, Y Lu, JY Wang. Significant Expansion of Fluorescent Protein Sensing Ability through the Genetic Incorporation of Superior Photo-Induced Electron-Transfer Quenchers Journal of the American Chemical Society, (2014)136(38), 13094-13097
4) X.H. Liu1, J.S. Li1, C. Hu, Q. Zhou, W. Zhang, M.R. Hu, J.Z. Zhou, J.Y. Wang. Significant Expansion of the Fluorescent Protein Chromophore through the Genetic Incorporation of a Metal-chelating Unnatural Amino Acid Angew Chem Intl Ed (2013) 52(18), 4805-4809
5) X.H. Liu1, J.S. Li1, J.S. Dong1, C. Hu, W.M. Gong, and J.Y. Wang. Genetic incorporation of a metal-chelating amino acid as a probe for protein electron transfer Angewandte Chemie International Edition (2012) ;51(41):10261-5
6) X.H. Liu1, Y. Yu1, C. Hu, W. Zhang, Y. Lu, and J.Y. Wang. Significant Increase of oxidase activity through the genetic incorporation of a Tyrosine-Histidine cross-link in a Myoglobin model of Heme-Copper oxidase Angewandte Chemie International Edition (2012);51(18):4312-6 |
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