title: Two-photon activation and excitation properties of PA-GFP in the 720-920-nm region.
abstract: This report covers the two-photon activation and excitation properties of the PA-GFP, a photoactivatable variant of the Aequorea victoria green fluorescent protein in the spectral region from 720 to 920 nm. It is known from this special form of the molecule that it has an increased level of fluorescence emission when excited at 488 nm after irradiation at lambda approximately 413 nm, under single-photon excitation conditions. Here, we show that upon two-photon irradiation, PA-GFP yields activation in the spectral region from 720 to 840 nm. After photoactivation, the excitation spectrum shifts maintaining the very same emission spectrum of the single-photon case for the native and photoactivated protein. Additionally, when comparing the conventional photoactivation at lambda = 405 nm with a two-photon one, a sharper and better controllable three-dimensional volume of activation is obtained.
authors.affiliation: INFM Genoa, Department of Physics, University of Genoa, Italy.
authors.forename: Marc
authors.initials: M
authors.lastname: Schneider
authors.forename: Sara
authors.initials: S
authors.lastname: Barozzi
authors.forename: Ilaria
authors.initials: I
authors.lastname: Testa
authors.forename: Mario
authors.initials: M
authors.lastname: Faretta
authors.forename: Alberto
authors.initials: A
authors.lastname: Diaspro
mesh_terms: D005456:Fluorescent Dyes; D049452:Green Fluorescent Proteins / Q000032:analysis* / Q000235:genetics / Q000378:metabolism* / Q000528:radiation effects; D006367:HeLa Cells; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D008027:Light; D036641:Microscopy, Fluorescence, Multiphoton / Q000379:methods*; D010777:Photochemistry / Q000379:methods*; D011994:Recombinant Proteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism / Q000528:radiation effects
chemical_list: D005456:Fluorescent Dyes; D011994:Recombinant Proteins; D049452:Green Fluorescent Proteins