title: Energetics of oxo- and thio-dipeptide formation via amino acid condensation: a systematic computational analysis.
abstract: Oxo-dipeptides and thio-dipeptides are built via condensation between couples of amino acids and amino thioacids, the latter with the carbonyl oxygen replaced by an sp(2) sulfur. We explored via in silico methods (PBE0/6-31G(d,p) and PBE0/6-311G(d,p)) all the possible combinations and built 800 dipeptides, whose structures were fully optimized. Maps of condensation energies are presented to highlight optimal partners leading to stable dipeptides and critical situations for which lower stability or instability is predicted in terms of Gibbs reaction free energies. To validate the feasibility of our computational investigation, we synthesized and compared the stabilities of two thionated dimers, namely -Gly[Ψ(CSNH)]Gly- and -Phe[Ψ(CSNH)]Phe-, characterized by diverging physico-chemical properties. To the best of our knowledge, this is the first systematic analysis reported for dipeptides built from natural amino acids as well as for their corresponding thio-analogs.
authors.affiliation: Dipartimento di Scienze Chimiche, Università degli Studi di Padova, Via Marzolo 1, 35131 Padova, Italy. laura.orian@unipd.it.
authors.forename: Mauro
authors.initials: M
authors.lastname: Torsello
authors.forename: Laura
authors.initials: L
authors.lastname: Orian
authors.forename: Marta
authors.initials: M
authors.lastname: De Zotti
authors.forename: Roberta
authors.initials: R
authors.lastname: Saini
authors.forename: Fernando
authors.initials: F
authors.lastname: Formaggio
authors.forename: Antonino
authors.initials: A
authors.lastname: Polimeno
mesh_terms: D000596:Amino Acids / Q000737:chemistry*; D003198:Computer Simulation; D004151:Dipeptides / Q000737:chemistry*; D008422:Materials Testing; D008956:Models, Chemical; D008958:Models, Molecular; D010100:Oxygen / Q000737:chemistry*; D044367:Phase Transition; D011487:Protein Conformation; D013438:Sulfhydryl Compounds / Q000737:chemistry*
chemical_list: D000596:Amino Acids; D004151:Dipeptides; D013438:Sulfhydryl Compounds; D010100:Oxygen