title: Secondary structure analyses of protein films on gold surfaces by circular dichroism.
abstract: In order to analyze the secondary structures of protein molecules adsorbed on gold surfaces, circular dichroism (CD) spectra were measured and the secondary structure contents of protein ultra-thin films were estimated quantitatively. A disulfide group was introduced to cytochrome b(562) (cyt.b562), which is a water-soluble b-type heme protein. The cyt.b562 molecules self-assembled to form an ultra-thin protein film both on a gold substrate modified with 2,2(')-dithiodiacetic acid and on a bare gold surface. CD measurements were carried out both in solution and in air, and these results were compared. The protein denaturation was partially prevented, not only in solution but also in air, by both the modification of the substrate and the introduction of the anchor group to the protein molecule. The secondary structure contents of ultra-thin protein films on flat gold surfaces were observed for the first time both in solution and in air by CD spectra.
authors.affiliation: Department of Chemistry and Biotechnology, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 223-8522, Japan.
authors.forename: Masafumi
authors.initials: M
authors.lastname: Shimizu
authors.forename: Kazutoshi
authors.initials: K
authors.lastname: Kobayashi
authors.forename: Hisayuki
authors.initials: H
authors.lastname: Morii
authors.forename: Keita
authors.initials: K
authors.lastname: Mitsui
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Knoll
authors.forename: Teruyuki
authors.initials: T
authors.lastname: Nagamune
mesh_terms: D002942:Circular Dichroism; D003573:Cytochrome b Group / Q000737:chemistry; D004220:Disulfides / Q000737:chemistry; D006046:Gold / Q000737:chemistry*; D008958:Models, Molecular; D017433:Protein Structure, Secondary
chemical_list: D003573:Cytochrome b Group; D004220:Disulfides; D006046:Gold