Poly-proline-based chiral stationary phases: a molecular dynamics study of triproline, tetraproline, pentaproline and hexaproline interfaces.
Poly-proline chains and derivatives have been recently examined as the basis for new chiral stationary phases in high performance liquid chromatography. The selectivity of poly-proline has been measured for peptides with up to ten proline units. In this article, we employ molecular dynamics simulations to examine the interfacial structure and solvation of surface-bound poly-proline chiral selectors. Specifically, we study the interfacial structure of trimethylacetyl-terminated poly-proline chains with three-to-six prolines. The surface includes silanol groups and end-caps, to better capture the characteristics of the stationary phase, and the solvent is either a polar water/methanol or a relatively apolar n-hexane/2-propanol mixture. We begin with a comprehensive ab initio study of the conformers, their energies, and an assessment of conformer flexibility. Force fields have been developed for each poly-proline selector. Molecular dynamics simulations are employed to study the preferred backbone conformations and solvent hydrogen bonding for different poly-proline/solvent interfaces. For triproline, the effect of two different terminal groups, trimethylacetyl and t-butyl carbamate are compared.
Department of Chemistry, Queen's University, Kingston, Ontario K7L 3N6, Canada.
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D008958:Models, Molecular; D056004:Molecular Dynamics Simulation; D010455:Peptides / Q000737:chemistry*; D013237:Stereoisomerism
D010455:Peptides; C011083:polyproline