title: Density functional theory studies of MTSL nitroxide side chain conformations attached to an activation loop.
abstract: A quantum mechanical (QM) method rooted on density functional theory (DFT) has been employed to determine conformations of the methane-thiosulfonate spin label (MTSL) attached to a fragment extracted from the activation loop of Aurora-A kinase. The features of the calculated energy surface revealed low energy barriers between isoenergetic minima, and the system could be described in a population of 76 rotamers that can be also considered for other systems since it was found that the [Formula: see text], [Formula: see text] and [Formula: see text] do not depend on the previous two dihedral angles. Conformational states obtained were seen to be comparable to those obtained in the α-helix systems studied previously, indicating that the protein backbone does not affect the torsional profiles significantly and suggesting the possibility to use determined conformations for other protein systems for further modelling studies.
authors.affiliation: The Photon Science Institute and School of Chemistry, EPSRC National EPR Facility and Service, University of Manchester, Manchester, M13 9PY UK.
authors.forename: Maria Grazia
authors.initials: MG
authors.lastname: Concilio
authors.affiliation: The Photon Science Institute and School of Chemistry, EPSRC National EPR Facility and Service, University of Manchester, Manchester, M13 9PY UK.
authors.forename: Alistair J
authors.initials: AJ
authors.lastname: Fielding
authors.affiliation: Astbury Centre for Structural and Molecular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT UK.
authors.forename: Richard
authors.initials: R
authors.lastname: Bayliss
authors.affiliation: Astbury Centre for Structural and Molecular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT UK.
authors.forename: Selena G
authors.initials: SG
authors.lastname: Burgess
keywords: Computational chemistry; DFT; EPR