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The interaction of cyclosporin and calmodulin
Author(s) -
Steiner Robert F.,
Albaugh Sharon
Publication year - 1990
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/bip.360290612
Subject(s) - calmodulin , chemistry , fluorescence , binding site , acceptor , molecule , a site , biophysics , stereochemistry , biochemistry , enzyme , organic chemistry , physics , quantum mechanics , biology , condensed matter physics
The interaction of cyclosporin A and dansyl cyclosporin A with bovine and wheat germ calmodulin has been monitored by measurements of induced changes in dansyl and bound toluidinyl naphthalene sulfonate fluorescence. The interaction is Ca 2+ ‐dependent and 1 : 1 Measurements of the efficiency of radiationless energy transfer from bound dansyl cyclosporin A to an acceptor group located on Cys‐27 of wheat germ calmodulin suggest that the primary binding site is not located on the N‐terminal lobe (residues 1–65). However, studies with proteolytic fragments of calmodulin indicate that elements of the N‐terminal half‐molecule (residues 1–77) may be involved in the stabilization of the binding site. The binding of cyclosporin alters the physical properties of calmodulin and, in particular, reduces the localized rotational mobility of a fluorescent probe.