title: First Hyperpolarizability of Collagen Using the Point Dipole Approximation.
abstract: The application of localized hyperpolarizabilities to predict a total protein hyperpolarizability is presented for the first time, using rat-tail collagen as a demonstration example. We employ a model comprising the quadratic Applequist point-dipole approach, the so-called LoProp transformation, and a procedure with molecular fractionation using conjugate caps to determine the atomic and bond contributions to the net β tensor of the collagen [(PPG)10]3 triple-helix. By using Tholes exponential damping modification to the dyadic tensor in the Applequist equations, a correct qualitative agreement with experiment is found. The intensity of the βHRS signal and the depolarization ratios are best reproduced by decomposing the LoProp properties into the atomic positions and using Tholes exponential damping with the original damping parameter. Some ramifications of the model for general protein property optimization are briefly discussed.
authors.affiliation: School of Biotechnology, Division of Theoretical Chemistry and Biology, KTH Royal Institute of Technology , SE-106 91 Stockholm, Sweden.
authors.forename: Ignat
authors.initials: I
authors.lastname: Harczuk
authors.affiliation: School of Biotechnology, Division of Theoretical Chemistry and Biology, KTH Royal Institute of Technology , SE-106 91 Stockholm, Sweden.
authors.forename: Olav
authors.initials: O
authors.lastname: Vahtras
authors.affiliation: School of Biotechnology, Division of Theoretical Chemistry and Biology, KTH Royal Institute of Technology , SE-106 91 Stockholm, Sweden.
authors.forename: Hans
authors.initials: H
authors.lastname: Ågren