1uhh

Crystal structure of cp-aequorin

spinqualitylabelsall models 1uhh, resolution 1.80Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 1uhh is a 2 chain structure with sequence from Aequorea victoria. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: CZP NonStd Res: MSE Related: 1ej3, 1el4, 1jf2, 1uhi, 1uhj, 1uhk Resources: FirstGlance, OCA, RCSB, PDBsum Function [AEQ2_AEQVI] Ca(2+)-dependent bioluminescence photoprotein. Displays an emission peak at 470 nm (blue light). Trace amounts of calcium ion trigger the intramolecular oxidation of the chromophore, coelenterazine into coelenteramide and CO(2) with the concomitant emission of light. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMed The photoprotein aequorin emits light by an intramolecular reaction in the presence of a trace amount of Ca(2+). Semi-synthetic aequorins, produced by replacing the coelenterazine moiety in aequorin with the analogues of coelenterazine, show widely different sensitivities to Ca(2+). To understand the structural basis of the Ca(2+)-sensitivity, we determined the crystal structures of four semi-synthetic aequorins (cp-, i-, br- and n-aequorins) at resolutions of 1.6-1.8 A. In general, the protein structures of these semi-synthetic aequorins are almost identical to native aequorin. Of the four EF-hand domains in the molecule, EF-hand II does not bind Ca(2+), and the loop of EF-hand IV is clearly deformed. It is most likely that the binding of Ca(2+) with EF-hands I and III triggers luminescence. Although little difference was found in the overall structures of aequorins investigated, some significant differences were found in the interactions between the substituents of coelenterazine moiety and the amino acid residues in the binding pocket. The coelenterazine moieties in i-, br-, and n-aequorins have bulky 2-substitutions, which can interfere with the conformational changes of protein structure that follow the binding of Ca(2+) to aequorin. In cp-aequorin, the cyclopentylmethyl group that substitutes for the original 8-benzyl group does not interact hydrophobically with the protein part, giving the coelenterazine moiety more conformational freedom to promote the light-emitting reaction. The differences of various semi-synthetic aequorins in Ca(2+)-sensitivity and reaction rate are explained by the capability of the involved groups and structures to undergo conformational changes in response to the Ca(2+)-binding. The crystal structures of semi-synthetic aequorins.,Toma S, Chong KT, Nakagawa A, Teranishi K, Inouye S, Shimomura O Protein Sci. 2005 Feb;14(2):409-16. Epub 2005 Jan 4. PMID:15632284 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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