title: Optimized and far-red-emitting variants of fluorescent protein eqFP611.
abstract: Fluorescent proteins (FPs) emitting in the far-red region of the spectrum are highly advantageous for whole-body imaging applications because scattering and absorption of long-wavelength light is markedly reduced in tissue. We characterized variants of the red fluorescent protein eqFP611 with bright fluorescence emission shifted up to 639 nm. The additional red shift is caused by a trans-cis isomerization of the chromophore. The equilibrium between the trans and cis conformations is strongly influenced by amino acid residues 143 and 158. Pseudo monomeric tags were obtained by further genetic engineering. For the red chromophores of eqFP611 variants, molar extinction coefficients of up to approximately 150,000 were determined by an approach that is not affected by the presence of molecules with nonfunctional red chromophores. The bright fluorescence makes the red-shifted eqFP611 variants promising lead structures for the development of near-infrared fluorescent markers. The red fluorescent proteins performed well in cell biological applications, including two-photon imaging.
authors: Institute of General Zoology and Endocrinology, University of Ulm, 89069 Ulm, Germany.
authors: Simone
authors: S
authors: Kredel
authors: Karin
authors: K
authors: Nienhaus
authors: Franz
authors: F
authors: Oswald
authors: Michael
authors: M
authors: Wolff
authors: Sergey
authors: S
authors: Ivanchenko
authors: Florian
authors: F
authors: Cymer
authors: Andreas
authors: A
authors: Jeromin
authors: Francois J
authors: FJ
authors: Michel
authors: Klaus-Dieter
authors: KD
authors: Spindler
authors: Ralf
authors: R
authors: Heilker
authors: G Ulrich
authors: GU
authors: Nienhaus
authors: Jörg
authors: J
authors: Wiedenmann
mesh_terms: D000042:Absorption; D015415:Biomarkers / Q000737:chemistry / Q000378:metabolism; D019281:Dimerization; D005453:Fluorescence; D006367:HeLa Cells; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008027:Light; D008164:Luminescent Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D050505:Mutant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D020836:Protein Structure, Quaternary; D013997:Time Factors; D000097573:Red Fluorescent Protein
chemical_list: D015415:Biomarkers; D008164:Luminescent Proteins; D050505:Mutant Proteins; D000097573:Red Fluorescent Protein