title: Probing the structural basis and adsorption mechanism of an enzyme on nano-sized protein carriers.
abstract: Silica nanoparticles (SiNPs) are important nano-sized, solid-state carriers/hosts to load, store, and deliver biological or pharmaceutical cargoes. They are also good potential solid supports to immobilize proteins for fundamental protein structure and dynamics studies. However, precaution is necessary when using SiNPs in these areas because adsorption might alter the activity of the cargoes, especially when enzymes are loaded. Therefore, it becomes important to understand the structural basis of the cargo enzyme activity changes, if there is any. The high complexity and dynamics of the nano-bio interface present many challenges. Reported here is a comprehensive study of the structure, dynamics, and activity of a model enzyme, T4 lysozyme, upon adsorption to a few surface-modified SiNPs using several experimental techniques. Not surprisingly, a significant activity loss on each studied SiNP was found. The structural basis of the activity loss was identified based on results from a unique technique, the Electron Paramagnetic Resonance (EPR) spectroscopy, which probes structural information regardless of the complexity. Several docking models of the enzyme on SiNPs with different surfaces, at different enzyme-to-SiNP ratios are proposed. Interestingly, we found that the adsorbed enzyme can be desorbed via pH adjustment, which highlighted the potential to use SiNPs for enzyme/protein delivery or storage due to the high capacity. In order to use SiNPs as enzyme hosts, minimizing the enzymatic activity loss upon adsorption is needed. Lastly, the work outlined here demonstrate the use of EPR in probing structural information on the complex (inorganic)nano-bio interface.
authors.affiliation: Department of Chemistry and Biochemistry, North Dakota State University, Fargo, ND 58108, USA. zhongyu.yang@ndsu.edu.
authors.forename: Yanxiong
authors.initials: Y
authors.lastname: Pan
authors.affiliation: Department of Chemistry and Biochemistry, North Dakota State University, Fargo, ND 58108, USA. zhongyu.yang@ndsu.edu.
authors.forename: Sunanda
authors.initials: S
authors.lastname: Neupane
authors.affiliation: Department of Chemistry and Biochemistry, North Dakota State University, Fargo, ND 58108, USA. zhongyu.yang@ndsu.edu.
authors.forename: Jasmin
authors.initials: J
authors.lastname: Farmakes
authors.affiliation: Jules Stein Eye Institute, University of California, Los Angeles, CA 90025, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Bridges
authors.affiliation: Department of Physics, North Dakota State University, Fargo, ND 58108, USA.
authors.forename: James
authors.initials: J
authors.lastname: Froberg
authors.affiliation: Department of Plant Sciences, North Dakota State University, Fargo, ND 58108, USA.
authors.forename: Jiajia
authors.initials: J
authors.lastname: Rao
authors.affiliation: Department of Pharmaceutical Sciences, North Dakota State University, Fargo, ND 58108, USA.
authors.forename: Steven Y
authors.initials: SY
authors.lastname: Qian
authors.affiliation: Department of Chemistry and Biochemistry, North Dakota State University, Fargo, ND 58108, USA. zhongyu.yang@ndsu.edu.
authors.forename: Guodong
authors.initials: G
authors.lastname: Liu
authors.affiliation: Department of Physics, North Dakota State University, Fargo, ND 58108, USA.
authors.forename: Yongki
authors.identifier: http://orcid.org/0000-0001-8890-8344
authors.initials: Y
authors.lastname: Choi
authors.affiliation: Department of Chemistry and Biochemistry, North Dakota State University, Fargo, ND 58108, USA. zhongyu.yang@ndsu.edu.
authors.forename: Zhongyu
authors.identifier: http://orcid.org/0000-0002-3018-3608
authors.initials: Z
authors.lastname: Yang
mesh_terms: D000327:Adsorption; D004578:Electron Spin Resonance Spectroscopy; D062105:Molecular Docking Simulation; D009113:Muramidase / Q000737:chemistry*; D053758:Nanoparticles; D017434:Protein Structure, Tertiary; D012822:Silicon Dioxide
chemical_list: D012822:Silicon Dioxide; D009113:Muramidase