title: Alteration of fluorescent protein spectroscopic properties upon cryoprotection.
abstract: Cryoprotection of a protein crystal by addition of small-molecule compounds may sometimes affect the structure of its active site. The spectroscopic and structural effects of the two cryoprotectants glycerol and ethylene glycol on the cyan fluorescent protein Cerulean were investigated. While glycerol had almost no noticeable effect, ethylene glycol was shown to induce a systematic red shift of the UV-vis absorption and fluorescence emission spectra. Additionally, ethylene glycol molecules were shown to enter the core of the protein, with one of them binding in close vicinity to the chromophore, which provides a sound explanation for the observed spectroscopic changes. These results highlight the need to systematically record spectroscopic data on crystals of light-absorbing proteins and reinforce the notion that fluorescent proteins must not been seen as rigid structures.
authors.affiliation: Structural Biology Group, European Synchrotron Radiation Facility, Grenoble, France. vonstett@esrf.fr
authors.forename: David
authors.initials: D
authors.lastname: von Stetten
authors.forename: Gaëlle O
authors.initials: GO
authors.lastname: Batot
authors.forename: Marjolaine
authors.initials: M
authors.lastname: Noirclerc-Savoye
authors.forename: Antoine
authors.initials: A
authors.lastname: Royant
mesh_terms: D000818:Animals; D003451:Cryoprotective Agents / Q000737:chemistry* / Q000378:metabolism; D018360:Crystallography, X-Ray; D019855:Ethylene Glycol / Q000737:chemistry / Q000378:metabolism; D005456:Fluorescent Dyes / Q000737:chemistry* / Q000378:metabolism; D005990:Glycerol / Q000737:chemistry / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000737:chemistry* / Q000378:metabolism; D037402:Hydrozoa / Q000737:chemistry* / Q000378:metabolism; D008958:Models, Molecular; D011485:Protein Binding; D011487:Protein Conformation; D013050:Spectrometry, Fluorescence; D013056:Spectrophotometry, Ultraviolet
chemical_list: D003451:Cryoprotective Agents; C485182:Cyan Fluorescent Protein; D005456:Fluorescent Dyes; D049452:Green Fluorescent Proteins; D019855:Ethylene Glycol; D005990:Glycerol