title: Experimental Detection of the Intrinsic Difference in Raman Optical Activity of a Photoreceptor Protein under Preresonance and Resonance Conditions.
abstract: Raman optical activity (ROA) is an advanced technique capable of detecting structural deformations of light-absorbing molecules embedded in chromophoric proteins. Resonance Raman (RR) spectroscopy is widely used to enhance the band intensities. However, theoretical work has predicted that under resonance conditions the ROA spectrum resembles the shape of the RR spectrum. Herein, we use photoactive yellow protein (PYP) to measure the first experimental data on the effect of changing the excitation wavelength on the ROA spectra of a protein. We observe a close similarity between the shape of the RR spectrum and the resonance ROA spectrum of PYP. Furthermore, we experimentally verify the theoretical prediction concerning the ratio of the amplitudes of the ROA and Raman spectra. Our data demonstrate that selecting an appropriate excitation wavelength is a key factor for extracting structural information on a protein active site using ROA spectroscopy.
authors.affiliation: Department of Chemistry and Applied Chemistry, Graduate School of Science and Engineering, Saga University, Saga 840-8502 (Japan).
authors.forename: Shojiro
authors.initials: S
authors.lastname: Haraguchi
authors.affiliation: Department of Microbiology and Molecular Genetics, Oklahoma State University, Stillwater, OK 74078 (USA).
authors.forename: Miwa
authors.initials: M
authors.lastname: Hara
authors.affiliation: Department of Chemistry and Applied Chemistry, Graduate School of Science and Engineering, Saga University, Saga 840-8502 (Japan).
authors.forename: Takahito
authors.initials: T
authors.lastname: Shingae
authors.affiliation: Department of Microbiology and Molecular Genetics, Oklahoma State University, Stillwater, OK 74078 (USA).
authors.forename: Masato
authors.initials: M
authors.lastname: Kumauchi
authors.affiliation: Department of Microbiology and Molecular Genetics, Oklahoma State University, Stillwater, OK 74078 (USA).
authors.forename: Wouter D
authors.initials: WD
authors.lastname: Hoff
authors.affiliation: Department of Chemistry and Applied Chemistry, Graduate School of Science and Engineering, Saga University, Saga 840-8502 (Japan). unno@cc.saga-u.ac.jp.
authors.forename: Masashi
authors.initials: M
authors.lastname: Unno
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry*; D013059:Spectrum Analysis, Raman / Q000379:methods*
chemical_list: D001426:Bacterial Proteins
keywords: Raman spectroscopy; biophysics; chromophores; circular dichroism; structural biology