@unpublished{pittir35861,
           month = {January},
           title = {Engineering a {\ensuremath{\beta}}?Turn Mimetic Torsion Balance For Conformational Control: Design, Synthetic Strategies and NMR Analysis},
          author = {Alyssa Lypson},
            year = {2019},
        keywords = {torsion balance, peptidomimetics, protein folding, {\ensuremath{\beta}}?turn mimic, conformational control, conformational constrain, molecular scaffolds, molecular design, synthesis, NMR, solid-phase synthesis, SPPS},
             url = {http://d-scholarship-dev.library.pitt.edu/35861/},
        abstract = {The molecular torsion balance concept was applied to a peptide-hybrid balance to accurately investigate the effects of amino acid changes on antiparallel {\ensuremath{\beta}}-sheet configuration and stability for applications in molecular recognition and computational drug design.  In this study, we report an engineered design of that balance for improved interchain alignment by introduction of noncovalent steric constraint at the reverse turn. Our design utilizes a restricted N-aryl bond rotation to impose a two-state folded model by incorporating an (ortho-tolyl)amide into a locked biaryl system.  The turn mimetic nucleates hairpin formation in an antiparallel {\ensuremath{\beta}}-sheet configuration upon attachment of peptide sequences, providing a minimal model system to investigate biologically interesting epitopes. Bromine installation ortho to peptide chain attachment sites imposed an additional degree of conformational control for improved thermodynamic stability in the folded conformation.  Our design approach, which relied upon Monte Carlo simulations of substituted native chorismate pyruvate lyase (CPL75-93), is described along with solution-phase and solid-phase synthetic strategies.  1H and 2D NMR experiments revealed improved interchain alignment to promote hydrogen bond formation in the conformationally controlled synthetic peptidomimetic torsion balance hybrid compared to a control molecule. Line shape analysis of low temperature 1H NMR data approximated rotational restriction around the aryl ether bond to be 11 kcal/mol at 193 K in CD2Cl2.  1H NMR AND 2D ROESY analyses reveal an improved shape to mimic the ends of an antiparallel {\ensuremath{\beta}}-sheet. Hydrogen bond formation has been identified between NH amide proton of the upper side chain (proton donor) and glycine acetamide of the lower side chain (proton donor) and glycine acetamide of the lower side chain (proton acceptor).  Results confirm bromine substituents impose noncovalent steric constraints ortho to the peptide side chains to reduce conformational entropy of the upper peptide chains.}
}