title: Ultraviolet resonance Raman evidence for the absence of tyrosinate in octopus rhodopsin and the participation of Trp residues in the transition to acid metarhodopsin.
abstract: The ultraviolet (244 nm) resonance Raman spectra of octopus rhodopsin and its photoproduct, acid metarhodopsin, do not give any evidence for a tyrosinate. This finding excludes the possibility that Tyr-112 serves as the counter anion to the protonated Schiff base as does Glu-113 in bovine rhodopsin. Upon photoconversion from rhodopsin to acid metarhodopsin, Trp and Tyr Raman bands decrease in intensity and concomitantly a Trp band shifts in frequency. The changes of Trp Raman bands are ascribed to changes in hydrophobic interactions and conformation, suggesting a possible role of Trp in the photoconversion process of octopus rhodopsin.
authors.affiliation: Pharmaceutical Institute, Tohoku University, Aobayama, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Hashimoto
authors.forename: H
authors.initials: H
authors.lastname: Takeuchi
authors.forename: M
authors.initials: M
authors.lastname: Nakagawa
authors.forename: M
authors.initials: M
authors.lastname: Tsuda
mesh_terms: D000818:Animals; D006860:Hydrogen Bonding; D008968:Molecular Conformation; D049831:Octopodiformes / Q000737:chemistry*; D017433:Protein Structure, Secondary; D012243:Rhodopsin / Q000031:analogs & derivatives* / Q000737:chemistry*; D012545:Schiff Bases; D013059:Spectrum Analysis, Raman; D014364:Tryptophan / Q000737:chemistry*; D014443:Tyrosine / Q000737:chemistry*
chemical_list: D012545:Schiff Bases; D014443:Tyrosine; C013110:metarhodopsins; D014364:Tryptophan; D012243:Rhodopsin