title: Graphene oxide-induced conformation changes of glucose oxidase studied by infrared spectroscopy.
abstract: The adsorption of proteins on the surface of nanomaterials can induce changes in the structure and biological activity of the proteins. Although there have been a number of studies aimed at developing an understanding of the interactions of proteins with surfaces of nanomaterials, a detailed description of the actual state of the adsorbed proteins or the functional consequences of protein adsorption onto nanomaterials has yet to be reported. In this study, the conformation changes of glucose oxidase (GOx) induced by adsorption on graphene oxide (GO) sheets were investigated by quantitative second-derivative infrared analysis and two-dimensional infrared correlation spectroscopy (2D IR). The adsorption of GOx on GO sheets resulted in the conversion of α-helix to β-sheet structures and therefore led to substantial conformation changes of GOx, even the unfolding of the protein. These alterations in the conformation of GOx caused a significant decrease in the catalytic activity of the enzyme for glucose oxidation. This study demonstrates that nanomaterials can strongly influence the conformation and activity of adsorbed proteins. In addition to the importance of this effect in cases of the direct adsorption of proteins on nanomaterials, the results have implications for proteins adsorbed on materials with nanometer-scale surface roughness.
authors.affiliation: Jiangsu Key Laboratory of New Power Batteries, College of Chemistry and Materials Science, Nanjing Normal University, Nanjing 210097, PR China.
authors.forename: Qian
authors.initials: Q
authors.lastname: Shao
authors.forename: Yingdan
authors.initials: Y
authors.lastname: Qian
authors.forename: Ping
authors.initials: P
authors.lastname: Wu
authors.forename: Hui
authors.initials: H
authors.lastname: Zhang
authors.forename: Chenxin
authors.initials: C
authors.lastname: Cai
mesh_terms: D000327:Adsorption; D005949:Glucose Oxidase / Q000737:chemistry* / Q000378:metabolism; D006108:Graphite / Q000737:chemistry*; D008968:Molecular Conformation; D010087:Oxides / Q000737:chemistry*; D010316:Particle Size; D013055:Spectrophotometry, Infrared; D013499:Surface Properties
chemical_list: D010087:Oxides; D006108:Graphite; D005949:Glucose Oxidase