Investigation of the cis-trans structures and isomerization of oligoprolines by using Raman spectroscopy and density functional theory calculations: solute-solvent interactions and effects of terminal positively charged amino acid residues.

ABSTRACT: Using low-wavenumber Raman spectroscopy in combination with theoretical calculations via solid-state density functional theory (DFT)-D3, we studied the vibrational structures and interaction with solvent of poly-l-proline and the oligoproline P12 series. The P12 series includes P12, the positively charged amino acid residue (arginine and lysine) N-terminus proline oligomers RP11 and KP11, and the C-terminus P11R and P11K. We assigned the spring-type phonon mode to 74-76 cm^-1 bands for the PPI and PPII conformers and the carbonyl group ring-opening mode 122 cm^-1 in the PPI conformer of poly-l-proline. Amide I and II were assigned based on the results of mode analysis for O, N, and C atom displacements. The broad band feature of the H-bond transverse mode in the

SUBMITTER: Huang MC 

PROVIDER: S-EPMC9056779 | biostudies-literature | 2020 Sep

REPOSITORIES: biostudies-literature