title: Nanorheology measurement on single circularly permuted green fluorescent protein molecule.
abstract: The force measurement mode of an atomic force microscope (AFM) has enabled us to measure the mechanical properties of biological materials at the single molecular level. In a conventional quasi-static force measurement on a single circularly permuted green fluorescent protein (cpGFP), we could unfold it by unraveling several sub-domains in a distinct sawtooth pattern at a slow stretching speed. In order to elucidate more detailed conformational changes at each extension length, we further measured dynamic relax-stress response of cpGFP molecules. In this measurement, several cycles of sinusoidal movement were applied to the sample during the stretching process. We found the protein molecule showed in-phase response to the sinusoidal input in most case of measurements.
authors.affiliation: Local Spatio-Temporal Functions Laboratory, Frontier Research System, RIKEN, Wako, Saitama 351-0198, Japan.
authors.forename: Tong
authors.initials: T
authors.lastname: Wang
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Sakai
authors.forename: Ken
authors.initials: K
authors.lastname: Nakajima
authors.forename: Atsushi
authors.initials: A
authors.lastname: Miyawaki
authors.forename: Kohzo
authors.initials: K
authors.lastname: Ito
authors.forename: Masahiko
authors.initials: M
authors.lastname: Hara
mesh_terms: D049452:Green Fluorescent Proteins / Q000737:chemistry*; D018625:Microscopy, Atomic Force / Q000379:methods*; D012212:Rheology; D013997:Time Factors
chemical_list: C485192:green fluorescent protein, Aequorea victoria; D049452:Green Fluorescent Proteins