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Frictional resistance to motions of bimane‐labelled spinach calmodulin in response to ligand binding
Author(s) -
Yuan Shixing,
Haug Alfred
Publication year - 1988
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 - 10.1016/0014-5793(88)81338-3
Subject(s) - calmodulin , fluorophore , chemistry , ligand (biochemistry) , fluorescence , spinach , stoichiometry , temperature coefficient , biophysics , fluorescence anisotropy , crystallography , analytical chemistry (journal) , biochemistry , materials science , membrane , biology , chromatography , physics , receptor , enzyme , quantum mechanics , composite material
The single cysteinyl residue 26 of spinach calmodulin was labelled with the thiol‐specific bimane fluorescence probe. Following application of stoichiometric quantities of Ca 2+ or aluminum ions to the protein, temperature‐dependent fluorescence changes (anisotropy, lifetime) could be monitored via the label. From these data the Y function could be constructed which, as a function of temperature, seems to consist of two linear regions which intersect at the critical temperature, T c . From the Y function the thermal coefficient, b ( T ), of the frictional resistance to fluorophore rotation could be determined. b ( T ) was dependent on the type and stoichiometry of the ligand(s) bound to calmodulin. Changes of the thermal coefficient apparently resulted in part from ligand‐triggered structural pertubations transmitted over a considerable distance to calmodulin region I, the site of the fluorophore.