3tmr | pdb_00003tmr

IrisFP, planar chromophore

spinqualitylabelsall models 3tmr, resolution 2.00Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 3tmr is a 4 chain structure with sequence from Lobophyllia hemprichii. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: SO3, SO4 NonStd Res: CR8 Related: 2vvh, 2vvi, 2vvj, 1zux, 2btj, 3tmt Resources: FirstGlance, OCA, RCSB, PDBsum Publication Abstract from PubMed Fluorescent proteins (FPs) of the green fluorescent protein family blink and bleach like all fluorophores. However, contrary to organic dyes, the mechanisms by which transient losses of fluorescence occur in FPs have received little attention. Here, we focus on the photoactivatable IrisFP, for which a transient non-fluorescent chromophoric state with distorted geometry was recently reported (Adam, V.; et al. J. Am. Chem. Soc.2009, 131, 18063). We investigated the chemical nature of this blinked state by employing quantum chemical/molecular mechanical calculations. Our findings suggest two previously unidentified dark states that display similar distorted chromophores with a transiently ruptured pi-electron system. Both are protonated at atom C(alpha) of the chromophore methylene bridge. Transient protonation may occur via proton transfer from the nearby Arg66 either in the triplet state T(1) after intersystem crossing or in an anionic radical (doublet) ground state. As Arg66 is conserved in green-to-red photoconvertible FPs, these dark states are predicted to be common to all these proteins. We also suggest that C(alpha) protonated dark states may accelerate photobleaching by favoring decarboxylation of the fully conserved Glu212. The Nature of Transient Dark States in a Photoactivatable Fluorescent Protein.,Roy A, Field MJ, Adam V, Bourgeois D J Am Chem Soc. 2011 Oct 31. PMID:22039963 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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