title: Redistribution and loss of side chain entropy upon formation of a calmodulin-peptide complex.
abstract: The response of the internal dynamics of calcium-saturated calmodulin to the formation of a complex with a peptide model of the calmodulin-binding domain of the smooth muscle myosin light chain kinase has been studied using NMR relaxation methods. The backbone of calmodulin is found to be unaffected by the binding of the domain, whereas the dynamics of side chains are significantly perturbed. The changes in dynamics are interpreted in terms of a heterogeneous partitioning between structure (enthalpy) and dynamics (entropy). These data provide a microscopic view of the residual entropy of a protein in two functional states and suggest extensive enthalpy/entropy exchange during the formation of a protein-protein interface.
authors.affiliation: The Johnson Research Foundation, Department of Biochemistry and Biophysics, School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
authors.forename: A L
authors.initials: AL
authors.lastname: Lee
authors.forename: S A
authors.initials: SA
authors.lastname: Kinnear
authors.forename: A J
authors.initials: AJ
authors.lastname: Wand
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002118:Calcium / Q000378:metabolism; D002147:Calmodulin / Q000737:chemistry* / Q000378:metabolism*; D002645:Chickens; D019277:Entropy; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009130:Muscle, Smooth / Q000201:enzymology; D009219:Myosin-Light-Chain Kinase / Q000737:chemistry / Q000378:metabolism; D010446:Peptide Fragments / Q000737:chemistry* / Q000378:metabolism*; D018583:Pliability; D011485:Protein Binding; D011487:Protein Conformation; D013816:Thermodynamics; D014867:Water / Q000378:metabolism
chemical_list: D002147:Calmodulin; D010446:Peptide Fragments; D014867:Water; D009219:Myosin-Light-Chain Kinase; D002118:Calcium