Associate Professor Guangnan Ou
Jimei University, China
Title: Construction of artificial metalloenzymes by protein refolding
Abstract:
Metalloenzymes contain a metal cofactor in a protein scaffold, which are involved in many biological processes such as nitrogen fixation, respiration, hydrocarbon oxidation, and oxygenic photosynthesis. Based on the function and mechanism of natural enzymes, in 2001, we proposed three catalytic action modes that for the best one the negative charge centers seem to be the active site for reactants or products, while the positive one seems to be the active site for transition states, resulting in great decrease in the activation energy. To meet the above requirements, artificial metalloenzymes (ArMs) can be constructed by anchoring a metal complex of positive charge on the pocket of a protein which periphery has negative charges.
To find a simple and versatile method for the incorporation of metal complexes within the protein host, lessons can be learned from protein folding. The protein folding forces include hydrophobic, electrostatic, hydrogen bond, and van der Waals interactions. In the case of metalloproteins, there is an additional folding force, ligand-metal interactions. It was reported that there is a direct relationship between folding and metal coordination. Inspired by metal-induced protein folding, we report here a simple and versatile method for the incorporation of metal complexes within the protein host by protein refolding,
The as-prepared artificial hemeprotein was characterized by UV-vis, CD, and MALDI-TOF-MS, which exhibited peroxidase-like activities with an optical pH at pH 7.0 and an optical temperature at 65°C. The Michaelis-Menten constant (Km) and maximum velocity (Vm) with guaiacol for the as-prepared hemeprotein was calculated to be 0.131 mM and 0.166 mM/s, which was significantly lower compared with the value of 39.7 mM and 44.4 mM/s of native horseradish peroxidase. The artificial hemeprotein had much more affinity to the guaiacol than HRP, and had lower guaiacol oxidation efficiency than HRP.
Biography:
Guangnan Ou, obtained his B.S. in chemistry at Sun Yat-sen University, China, in 1985, and his Ph.D. in physical chemistry at Xiamen University, China, in 2007. In 1991, he joined the faculty of Jimei University, China, where he is now associate professor of chemistry. He worked as an Academic Visitor under the supervision of Prof. Peter Halling at the University of Strathclyde for the period 1 September 2013 to 31 August 2014. His research interests focus on nonaqueous enzymatic catalysis, ionic liquid, chemical protein modification, and artificial enzyme.
Representative Publications
Book chapters
G. N. Ou. Chapter 17 Enzymatic Catalysis In Buffered Ionic Liquids. In: Handbook of Ionic Liquids. Editor: Jihoon Mun and Haeun Sim. New York: Nova Science Publishers, Inc. 2012.
Articles
1. G. N. Ou, B. Y. He and P. Halling. Ionization basis for activation of enzymes soluble in ionic liquids. Biochim. Biophys. Acta, Gen. Subj. 2016, 1860, 1404-1408.
2. G. N. Ou, B. Y. He and Y. Z. Yuan. Design of biosolvents through hydroxyl-functionalization of compounds with high dielectric constant. Appl. Biochem. Biotechnol. 2012, 166, 1472-1479.
3. G. N. Ou, B. Y. He and Y. Z. Yuan. Lipases are soluble and active in glycerol carbonate as a novel biosolvent. Enzyme Microb Technol. 2011, 49(2): 167-170.
4. G. N. Ou, J. Yang, B. Y. He and Y. Z. Yuan. Buffer-mediated activation of Candida antarctica lipase B dissolved in hydroxyl-functionalized ionic liquids. J. Mol. Catal. B: Enzym. 2011, 68 (1): 66-70.
5. G. N. Ou, L. Xu, B. Y. He and Y. Z. Yuan. Enhanced stability of charged dendrimer-encapsulated Pd nanoparticles in ionic liquids. Chem. Comm. 2008, 4210-4212.
6. G. N. Ou, M. X. Zhu, J. R. She and Y. Z. Yuan. Ionic liquid buffers: a new class of chemicals with potential for controlling pH in non-aqueous media. Chem. Comm. 2006, 4626-4628.