title: Tuning the electronic absorption of protein-embedded all-trans-retinal.
abstract: Protein-chromophore interactions are a central component of a wide variety of critical biological processes such as color vision and photosynthesis. To understand the fundamental elements that contribute to spectral tuning of a chromophore inside the protein cavity, we redesigned human cellular retinol binding protein II (hCRBPII) to fully encapsulate all-trans-retinal and form a covalent bond as a protonated Schiff base. This system, using rational mutagenesis designed to alter the electrostatic environment within the binding pocket of the host protein, enabled regulation of the absorption maximum of the pigment in the range of 425 to 644 nanometers. With only nine point mutations, the hCRBPII mutants induced a systematic shift in the absorption profile of all-trans-retinal of more than 200 nanometers across the visible spectrum.
authors.affiliation: Department of Chemistry, Michigan State University, East Lansing, MI 48824, USA.
authors.forename: Wenjing
authors.initials: W
authors.lastname: Wang
authors.forename: Zahra
authors.initials: Z
authors.lastname: Nossoni
authors.forename: Tetyana
authors.initials: T
authors.lastname: Berbasova
authors.forename: Camille T
authors.initials: CT
authors.lastname: Watson
authors.forename: Ipek
authors.initials: I
authors.lastname: Yapici
authors.forename: Kin Sing Stephen
authors.initials: KS
authors.lastname: Lee
authors.forename: Chrysoula
authors.initials: C
authors.lastname: Vasileiou
authors.forename: James H
authors.initials: JH
authors.lastname: Geiger
authors.forename: Babak
authors.initials: B
authors.lastname: Borhan
mesh_terms: D000042:Absorption; D004583:Electrons; D006801:Humans; D016296:Mutagenesis; D017354:Point Mutation; D012172:Retinaldehyde / Q000031:analogs & derivatives* / Q000737:chemistry; D054840:Retinol-Binding Proteins, Cellular / Q000737:chemistry* / Q000235:genetics; D055672:Static Electricity
chemical_list: D054840:Retinol-Binding Proteins, Cellular; C525876:retinal dimer; D012172:Retinaldehyde