Chiral Inversion of Amino Acids in Antiparallel β-Sheets at Interfaces Probed by Vibrational Sum Frequency Generation Spectroscopy.

ABSTRACT: A parallel study of protein variants with all (l-), all (d-), or mixed (l-)/(d-) amino acids can be used to assess how backbone architecture versus side chain identity determines protein structure. Here, we investigate the secondary structure and side chain orientation dynamics of the antiparallel β-sheet peptide LK₇β (Ac-Leu-Lys-Leu-Lys-Leu-Lys-Leu-NH₂) composed of all (l-), all (d-), or alternating (l-Leu)/(d-Lys) amino acids. Using interface-selective vibrational sum frequency generation spectroscopy (VSFG), we observe that the alternating (l-)/(d-) peptide lacks a resonant C-H stretching mode compared to the (l-) and (d-) variants and does not form antiparallel β-sheets. We rationalize our observations on the basis of density functional theory calculations and mol

SUBMITTER: Perets EA 

PROVIDER: S-EPMC9059514 | biostudies-literature | 2019 Jul

REPOSITORIES: biostudies-literature