This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Nousiainen, M. Articles by Vainiotalo, P. Search for Related Content PubMed PubMed Citation Articles by Nousiainen, M. Articles by Vainiotalo, P.

Relative Affinity Constants by Electrospray Ionization and Fourier Transform Ion Cyclotron Resonance Mass Spectrometry: Calmodulin Binding to Peptide Analogs of Myosin Light Chain Kinase

Marjaana Nousiainen ^*, Peter J. Derrick , Daniel Lafitte  and Pirjo Vainiotalo ^*

^* Department of Chemistry, University of Joensuu, FIN-80101 Joensuu, Finland; Institute of Mass Spectrometry and Department of Chemistry, University of Warwick, Coventry CV4 7AL, United Kingdom; and UPRESA CNRS 6032, 13385 Marseille, France

Correspondence: Address reprint requests to Prof. P. J. Derrick, Institute of Mass Spectrometry and Dept. of Chemistry, University of Warwick, Coventry CV4 7AL, UK. Tel.: +44 (0)24 76 523818; Fax: +44 (0)24 76 523819; E-mail: p.j.derrick{at}warwick.ac.uk.

Synthetic RS20 peptide and a set of its point-mutated peptide analogs have been used to analyze the interactions between calmodulin (CaM) and the CaM-binding sequence of smooth-muscle myosin light chain kinase both in the presence and the absence of Ca²⁺. Particular peptides, which were expected to have different binding strengths, were chosen to address the effects of electrostatic and bulky mutations on the binding affinity of the RS20 sequence. Relative affinity constants for protein/ligand interactions have been determined using electrospray ionization and Fourier transform ion cyclotron resonance mass spectrometry. The results evidence the importance of electrostatic forces in interactions between CaM and targets, particularly in the presence of Ca²⁺, and the role of hydrophobic forces in contributing additional stability to the complexes both in the presence and the absence of Ca²⁺.