title: Solvent-induced differentiation of protein backbone hydrogen bonds in calmodulin.
abstract: In apo and holoCaM, almost half of the hydrogen bonds (H-bonds) at the protein backbone expected from the corresponding NMR or X-ray structures were not detected by h3JNC' couplings. The paucity of the h3JNC' couplings was considered in terms of dynamic features of these structures. We examined a set of seven proteins and found that protein-backbone H-bonds form two groups according to the h3JNC' couplings measured in solution. H-bonds that have h3JNC' couplings above the threshold of 0.2 Hz show distance/angle correlation among the H-bond geometrical parameters, and appear to be supported by the backbone dynamics in solution. The other H-bonds have no such correlation; they populate the water-exposed and flexible regions of proteins, including many of the CaM helices. The observed differentiation in a dynamical behavior of backbone H-bonds in apo and holoCaM appears to be related to protein functions.
authors.affiliation: Department of Biochemistry and Molecular Biology, Mayo College of Medicine, Mayo Clinic and Foundation, Rochester, MN 55905, USA. juranic.nenad@mayo.edu
authors.forename: Nenad
authors.initials: N
authors.lastname: Juranić
authors.forename: Elena
authors.initials: E
authors.lastname: Atanasova
authors.forename: John H
authors.initials: JH
authors.lastname: Streiff
authors.forename: Slobodan
authors.initials: S
authors.lastname: Macura
authors.forename: Franklyn G
authors.initials: FG
authors.lastname: Prendergast
mesh_terms: D002147:Calmodulin / Q000737:chemistry* / Q000235:genetics; D006801:Humans; D006860:Hydrogen Bonding; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008958:Models, Molecular; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D011994:Recombinant Proteins / Q000737:chemistry; D020539:Sequence Analysis, Protein; D012997:Solvents / Q000737:chemistry*
chemical_list: D002147:Calmodulin; D011994:Recombinant Proteins; D012997:Solvents