European Journal of Mass Spectrometry - Abstract of Monitoring conformational changes in protein complexes using chemical cross- linking and Fourier transform ion cyclotron resonance mass spectrometry: the effect of calcium binding on the calmodulin

Monitoring conformational changes in protein complexes using chemical cross- linking and Fourier transform ion cyclotron resonance mass spectrometry: the effect of calcium binding on the calmodulin–melittin complex

Petr Novak,^a,* Vladimir Havlicek,^a Peter J. Derrick,^b,e Kyle A. Beran,^c Sajid Bashir^d and Anastassios E. Giannakopulos^b,f
^aInstitute of Microbiology, Academy of Sciences, Prague, Czech Republic
^bDepartment of Chemistry, University of Warwick, Coventry, CV4 7AL, UK
^cDepartment of Science & Mathematics, The University of Texas of the Permian Basin, Odessa, TX 79762, USA
^dChemical Biology Research Group, Department of Chemistry, Texas A&M-Kingsville, Kingsville, TX 78363, USA
^eCurrent address: Institute of Fundamental Sciences, Massey University, Private Bag 11 222, Palmerston North, New Zealand
^fCurrent address: ThermoFisher Scientific, Hanna- Kunath-Str. 11, 28199 Bremen, Germany

Calmodulin is an EF hand calcium binding protein. Its binding affinities to various protein/peptide targets often depend on the conformational changes induced by the binding of calcium. One such target is melittin, which binds tightly to calmodulin in the presence of calcium, and inhibits its function. Chemical cross-linking combined with Fourier transform ion cyclotron resonance mass spectrometry has been employed to investigate the coordination of calmodulin and melittin in the complex at different concentrations of calcium. This methodology can be used to monitor structural changes of proteins induced by ligand binding, and study the effects these changes have on non-covalent interactions between proteins. Cross-linking results indicate that the binding place of the first melittin in the calcium free calmodulin form is the same as in the calcium loaded calmodulin/ melittin complex.