title: Tetrapeptide unfolding dynamics followed by core-level spectroscopy: a first-principles approach.
abstract: In this work we demonstrate that core level analysis is a powerful tool for disentangling the dynamics of a model polypeptide undergoing conformational changes in solution and disulphide bond formation. In particular, we present computer simulations within both initial and final state approximations of 1s sulphur core level shifts (S1s CLS) of the CYFC (cysteine-phenylalanine-tyrosine-cysteine) tetrapeptide for different folding configurations. Using increasing levels of accuracy, from Hartree-Fock and density functional theory to configuration interaction via a multiscale algorithm capable of reducing drastically the computational cost of electronic structure calculations, we find that distinct peptide arrangements present S1s CLS sizeably different (in excess of 0.5 eV) with respect to the reference disulfide bridge state. This approach, leading to experimentally detectable signals, may represent an alternative to other established spectroscopic techniques.
authors.affiliation: European Centre for Theoretical Studies in Nuclear Physics and Related Areas (ECT*), Bruno Kessler Foundation, and Trento Institute for Fundamental Physics and Applications (INFN-TIFPA), Trento, Italy. taioli@fbk.eu.
authors.forename: Simone
authors.initials: S
authors.lastname: Taioli
authors.forename: Stefano
authors.initials: S
authors.lastname: Simonucci
authors.forename: Silvio
authors.initials: S
authors.lastname: A Beccara
authors.forename: Marco
authors.initials: M
authors.lastname: Garavelli
mesh_terms: D000465:Algorithms; D003198:Computer Simulation; D009842:Oligopeptides / Q000737:chemistry*; D056951:Photoelectron Spectroscopy; D011487:Protein Conformation; D058767:Protein Unfolding; D011789:Quantum Theory
chemical_list: D009842:Oligopeptides