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Ligand binding and conformational states of the photoprotein obelin
Author(s) -
Eremeeva Elena V.,
Vysotski Eugene S.,
Westphal Adrie H.,
van Mierlo Carlo P.M.,
van Berkel Willem J.H.
Publication year - 2012
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/j.febslet.2012.10.015
Subject(s) - photoprotein , chemistry , ligand (biochemistry) , crystallography , conformational change , covalent bond , circular dichroism , thermal stability , calcium , biophysics , stereochemistry , biochemistry , receptor , biology , organic chemistry
Many proteins require a non‐covalently bound ligand to be functional. How ligand binding affects protein conformation is often unknown. Here we address thermal unfolding of the free and ligand‐bound forms of photoprotein obelin. Fluorescence and far‐UV circular dichroism (CD) data show that the various ligand‐dependent conformational states of obelin differ significantly in stability against thermal unfolding. Binding of coelenterazine and calcium considerably stabilizes obelin. In solution, all obelin structures are similar, except for apo‐obelin without calcium. This latter protein is an ensemble of conformational states, the populations of which alter upon increasing temperature.