title: Paramagnetic relaxation enhancement for the characterization of the conformational heterogeneity in two-domain proteins.
abstract: Multidomain proteins are often composed of rigid domains that can reorient in solution more or less freely. Calmodulin (CaM) is a two domain protein which can experience a large degree of conformational freedom thanks to a mobile linker connecting the N-terminal and C-terminal domains of the protein. The maximum occurrences (MOs) of the possible protein conformations have been analyzed using the paramagnetic relaxation enhancements (PREs) induced by a gadolinium(III) ion together with the paramagnetic pseudocontact shift and residual dipolar coupling restraints measured in the presence of terbium(III), thulium(III) or dysprosium(III) ions. The results suggest that the PREs provide complementary information useful for improving the description of the conformational heterogeneity of the protein. The data, acquired at 298 K and at 278 K, suggest that compact conformations are disfavoured by decreasing the temperature.
authors.affiliation: Magnetic Resonance Center (CERM), University of Florence, Via L. Sacconi 6, 50019 Sesto Fiorentino (FI), Italy. ivanobertini@cerm.unifi.it
authors.forename: Ivano
authors.initials: I
authors.lastname: Bertini
authors.forename: Claudio
authors.initials: C
authors.lastname: Luchinat
authors.forename: Malini
authors.initials: M
authors.lastname: Nagulapalli
authors.forename: Giacomo
authors.initials: G
authors.lastname: Parigi
authors.forename: Enrico
authors.initials: E
authors.lastname: Ravera
mesh_terms: D000465:Algorithms; D002147:Calmodulin / Q000737:chemistry*; D005682:Gadolinium / Q000737:chemistry; D028581:Lanthanoid Series Elements / Q000737:chemistry; D008958:Models, Molecular; D019906:Nuclear Magnetic Resonance, Biomolecular / Q000379:methods*; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D013696:Temperature
chemical_list: D002147:Calmodulin; D028581:Lanthanoid Series Elements; D005682:Gadolinium