title: Application of a sensitive near-field microwave microprobe to the nondestructive characterization of microbial rhodopsin.
abstract: We study the opto-electrical properties of Natronomonas pharaonis sensory rhodopsin II (NpSRII) by using a near-field microwave microprobe (NFMM) under external light illumination. To investigate the possibility of application of NFMM to biological macromolecules, we used time dependent properties of NPSRII before/after light activation which has three distinct states - ground-state, M-state, and O-state. The diagnostic ability of NFMM is demonstrated by measuring the microwave reflection coefficient (S(11)) spectrum of NpSRII under steady-state illumination in the wavelength range of 350-650 nm. Moreover, we present microwave reflection coefficient S(11) spectra in the same wavelength range for two fast-photocycling rhodopsins: green light-absorbing proteorhodopsin (GPR) and Gloeobacter rhodopsin (GR). In addition the frequency sweep shift can be detected completely even for tiny amounts of sample (∼10(-3) OD of rhodopsin). Based on these results NFMM shows both very high sensitivity for detecting conformational changes and produces a good time-resolved spectrum.
authors.affiliation: Department of Physics, Kunsan National University, Gunsan 573-701, Korea.
authors.forename: Songhui
authors.initials: S
authors.lastname: Kim
authors.forename: Youngwoon
authors.initials: Y
authors.lastname: Yoon
authors.forename: Hanju
authors.initials: H
authors.lastname: Lee
authors.forename: Ah Reum
authors.initials: AR
authors.lastname: Choi
authors.forename: Kwang-Hwan
authors.initials: KH
authors.lastname: Jung
authors.forename: Arsen
authors.initials: A
authors.lastname: Babajanyan
authors.forename: Tigran
authors.initials: T
authors.lastname: Abrahamyan
authors.forename: Hyungkeun
authors.initials: H
authors.lastname: Yoo
authors.forename: Jung-Ha
authors.initials: JH
authors.lastname: Lee
authors.forename: Deokjoon
authors.initials: D
authors.lastname: Cha
authors.forename: Gerard
authors.initials: G
authors.lastname: Berthiau
authors.forename: Barry
authors.initials: B
authors.lastname: Friedman
authors.forename: Kiejin
authors.initials: K
authors.lastname: Lee
mesh_terms: D025602:Halorhodopsins / Q000737:chemistry / Q000528:radiation effects; D008872:Microwaves; D008962:Models, Theoretical; D055096:Optical Devices; D055620:Optical Phenomena; D011487:Protein Conformation; D055550:Protein Stability; D012243:Rhodopsin / Q000737:chemistry / Q000528:radiation effects; D025604:Rhodopsins, Microbial / Q000737:chemistry* / Q000528:radiation effects; D025603:Sensory Rhodopsins / Q000737:chemistry / Q000528:radiation effects; D013053:Spectrophotometry
chemical_list: D025602:Halorhodopsins; D025604:Rhodopsins, Microbial; D025603:Sensory Rhodopsins; C413548:proteorhodopsin; C061508:sensory rhodopsin II protein, archaeal; D012243:Rhodopsin