Influence of graphene oxide and reduced graphene oxide on the activity and conformation of lysozyme.
The dramatically different bio-effects of graphene and graphene oxide (GO) have been widely observed in diverse biological systems, which determine the applications and toxicity of graphene materials. To elucidate the mechanism at molecular level, it is urgent to investigate the enzyme-graphene interaction and its consequences. In this study, we comparatively studied the influence of GO and reduced GO (RGO) on the activity and conformation of lysozyme to provide better understandings of their different bio-effects. Both GO and RGO adsorbed large quantities of lysozyme after incubation. GO inhibited lysozyme activity seriously, while RGO nearly had no influence on the enzyme activity. The different inhibitions of enzyme activity could be explained by the lysozyme conformational changes, where GO induced more changes to the protein conformation according to UV-vis absorbance, far-UV circular dichroism spectra, intrinsic fluorescence quenching, and infrared spectra. Based on the spectroscopic changes of lysozyme, GO induced the loss of secondary structure and exposed the active site of lysozyme more to the aqueous environment. In addition, neither GO nor RGO induced the fibrillation of lysozyme after 12d incubation. The results collectively indicated that the oxidation degree significantly impacted the enzyme-graphene interaction. The implications to the designs of enzyme-graphene system for bio-related applications and the toxicological effects of graphene materials are discussed.
College of Chemistry and Environment Protection Engineering, Southwest Minzu University, Chengdu 610041, China.
Yitong
Y
Bai
College of Chemistry and Environment Protection Engineering, Southwest Minzu University, Chengdu 610041, China.
Zhu
Z
Ming
Institute of Nanochemistry and Nanobiology, Shanghai University, Shanghai 200444, China.
Yuye
Y
Cao
College of Chemistry and Environment Protection Engineering, Southwest Minzu University, Chengdu 610041, China.
Shicheng
S
Feng
College of Chemistry and Environment Protection Engineering, Southwest Minzu University, Chengdu 610041, China.
Hua
H
Yang
College of Chemistry and Environment Protection Engineering, Southwest Minzu University, Chengdu 610041, China.
Lingyun
L
Chen
College of Chemistry and Environment Protection Engineering, Southwest Minzu University, Chengdu 610041, China. Electronic address: yangst@pku.edu.cn.
Sheng-Tao
ST
Yang
D000327:Adsorption; D000818:Animals; D002942:Circular Dichroism; D004800:Enzymes, Immobilized / Q000737:chemistry / Q000378:metabolism; D006108:Graphite / Q000737:chemistry*; D009113:Muramidase / Q000737:chemistry* / Q000378:metabolism*; D010084:Oxidation-Reduction; D011487:Protein Conformation; D013050:Spectrometry, Fluorescence; D013056:Spectrophotometry, Ultraviolet
D004800:Enzymes, Immobilized; D006108:Graphite; D009113:Muramidase
Adsorption; Bio-effect of nanomaterials; Enzyme activity; Graphene; Protein conformation