title: Reversible pH-driven conformational switching of tethered superoxide dismutase with gold nanoparticle enhanced surface plasmon resonance spectroscopy.
abstract: A new class of surface-immobilized protein nanomachines can be reversibly actuated by cycling the solution pH between 2.5 and 12.3, which induces a conformational change, thereby modulating the thickness of superoxide dismutase (SOD1) tethered to the Au thin film. By placing Au nanoparticles (AuNP) atop the immobilized SOD1 by means of a gold-thiol assembly, the nanoscale motion of SOD1 at the interface produces mechanical work to lift and then lower the AuNP from the Au substrate by a distance of ca. 3 nm and transduces this motion into an easily measurable reflectivity change in the surface plasmon resonance (SPR) spectrum. As-made supported conjugate consisting of SOD1 and AuNP is quite robust and stable, and its operation in response to pH variations, which mirrors the conformational changes of responsive SOD1 at the interface, is found to be highly reversible and reproducible. This is the first demonstration of the development of novel solid-state sensors and/or switching devices based on substrate-bound protein conformational changes and AuNP enhanced SPR spectroscopy.
authors.affiliation: College of Medicine and School of Chemical and Biological Engineering, Institute of Chemical Processes, Seoul National University, San 56-1, Shillim, Kwanak, Seoul 151-742, Korea.
authors.forename: Taewook
authors.initials: T
authors.lastname: Kang
authors.forename: Surin
authors.initials: S
authors.lastname: Hong
authors.forename: Inhee
authors.initials: I
authors.lastname: Choi
authors.forename: Jung Jun
authors.initials: JJ
authors.lastname: Sung
authors.forename: Younjung
authors.initials: Y
authors.lastname: Kim
authors.forename: Ji-Sook
authors.initials: JS
authors.lastname: Hahn
authors.forename: Jongheop
authors.initials: J
authors.lastname: Yi
mesh_terms: D004800:Enzymes, Immobilized / Q000737:chemistry*; D006046:Gold / Q000737:chemistry*; D006801:Humans; D053768:Metal Nanoparticles / Q000737:chemistry*; D018625:Microscopy, Atomic Force; D011487:Protein Conformation; D013482:Superoxide Dismutase / Q000737:chemistry*; D000072105:Superoxide Dismutase-1; D020349:Surface Plasmon Resonance / Q000379:methods
chemical_list: D004800:Enzymes, Immobilized; C000606290:SOD1 protein, human; D006046:Gold; D013482:Superoxide Dismutase; D000072105:Superoxide Dismutase-1