Coenzyme Coupling Boosts Charge Transport through Single Bioactive Enzyme Junctions

Xiaoyan Zhuang; Aihui Zhang; Siyao Qiu; Chun Tang; Shiqiang Zhao; Hongchun Li; Yonghui Zhang; Yali Wang; Binju Wang; Baishan Fang; Wenjing Hong

doi:10.1016/j.isci.2020.101001

Coenzyme Coupling Boosts Charge Transport through Single Bioactive Enzyme Junctions

iScience. 2020 Apr 24;23(4):101001. doi: 10.1016/j.isci.2020.101001. Epub 2020 Mar 21.

Authors

Xiaoyan Zhuang¹, Aihui Zhang¹, Siyao Qiu², Chun Tang³, Shiqiang Zhao³, Hongchun Li⁴, Yonghui Zhang⁵, Yali Wang¹, Binju Wang³, Baishan Fang⁶, Wenjing Hong⁷

Affiliations

¹ State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China; The Key Laboratory for Chemical Biology of Fujian Province, Key Lab for Synthetic Biotechnology of Xiamen City, Xiamen University, Xiamen 361005, China.
² Science & Technology Innovation Institute, Dongguan University of Technology, Dongguan 523018, China.
³ State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China.
⁴ Research Center for Computer-Aided Drug Discovery, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China.
⁵ College of Food and Biology Engineering, Jimei University, Xiamen 361005, China.
⁶ State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China; The Key Laboratory for Chemical Biology of Fujian Province, Key Lab for Synthetic Biotechnology of Xiamen City, Xiamen University, Xiamen 361005, China. Electronic address: fbs@xmu.edu.cn.
⁷ State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China. Electronic address: whong@xmu.edu.cn.

Abstract

Oxidation of formate to CO₂ is catalyzed via the donation of electrons from formate dehydrogenase (FDH) to nicotinamide adenine dinucleotide (NAD⁺), and thus the charge transport characteristics of FDH become essential but remain unexplored. Here, we investigated the charge transport through single-enzyme junctions of FDH using the scanning tunneling microscope break junction technique (STM-BJ). We found that the coupling of NAD⁺ with FDH boosts the charge transport by ∼2,100%, and the single-enzyme conductance highly correlates with the enzyme activity. The combined flicker noise analysis demonstrated the switching of the coenzyme-mediated charge transport pathway and supported by the significantly reduced HOMO-LUMO gap from calculations. Site-specific mutagenesis analysis demonstrated that FDH-NAD⁺ stably combined own higher bioactivity and boosts charge transport, and the coupling has been optimized via the natural selection. Our work provides evidence of hydrogen bond coupling in bioactivity but also bridges the charge transport through single-enzyme junctions and enzyme activities.

Keywords: Analytical Chemistry; Biotechnology; Molecular Biology.