Characterization of covalently bonded proteins on poly(methyl methacrylate) by X-ray photoelectron spectroscopy

• Published in: Colloids and surfaces, B, Biointerfaces Vol. 78; no. 1; pp. 61 - 68
• Main Authors: Nelson, Geoffrey W., Perry, Megan, He, Shu-Mei, Zechel, David L., Horton, J. Hugh
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 15-06-2010
• Subjects: Amino Acid Sequence; Bacterial Proteins - chemistry; Bacterial Proteins - metabolism; beta-Glucosidase - chemistry; beta-Glucosidase - metabolism; Biosensor; Bonding; Covalence; Crystallography, X-Ray; Elements; Molecular Sequence Data; Photoelectron Spectroscopy; Poly(methylmethacrylate); Polymethyl Methacrylate - chemistry; Polymethyl Methacrylate - metabolism; Polymethyl methacrylates; Proteins; Surface modification; Surface Properties; Terminals; Thermotoga maritima; Thermotoga maritima - enzymology; X-ray photoelectron spectroscopy; X-rays; XPS; Poly(methylmethacrylate); Proteins; Surface modification; XPS; Biosensor
• ISSN: 0927-7765; 1873-4367
• DOI: 10.1016/j.colsurfb.2010.02.012

X-ray photoelectron spectroscopy (XPS) has been used to characterize a poly(methyl methacrylate) (PMMA) surface with covalently attached proteins. The PMMA surfaces were first aminated using hexamethyldiamine; the resulting –NH
2 sites were reacted with the hetero-bifunctional cross-linker Sulfo-EMCS to form a maleimide-terminated surface. The N-hydroxysuccinimide ester terminal and maleimide terminal groups of Sulfo-EMCS reacts with amine and sulfhydryl groups, respectively, exposed on the surface of the proteins. This study characterizes
Thermotoga maritima β-glucosidase 1 (TmGH1), which belongs to a family of proteins that facilitate hydrolysis of glucose-related monomers with retention of conformation. The surfaces were characterized by XPS to monitor surface composition, and to elucidate protein orientation on the surface. Results suggest that a covalently bonded surface of TmGH1 on PMMA has been obtained. These results demonstrate the feasibility of using XPS to study protein surface chemistry and demonstrate a useful method to anchor cysteine-terminated proteins for the purposes of creating biosensors or platforms for mechanical force experiments to investigate protein structure.