Hatfield MPD, Murphy RF, Lovas S. VCD spectroscopic properties of the beta-hairpin forming miniprotein CLN025 in various solvents.
Biopolymers 2010;
93:442-50. [PMID:
19937759 PMCID:
PMC4499852 DOI:
10.1002/bip.21356]
[Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Electronic and vibrational circular dichroism are often used to determine the secondary structure of proteins, because each secondary structure has a unique spectrum. Little is known about the vibrational circular dichroic spectroscopic features of the beta-hairpin. In this study, the VCD spectral features of a decapeptide, YYDPETGTWY (CLN025), which forms a stable beta-hairpin that is stabilized by intramolecular weakly polar interactions and hydrogen bonds were determined. Molecular dynamics simulations and ECD spectropolarimetry were used to confirm that CLN025 adopts a beta-hairpin in water, TFE, MeOH, and DMSO and to examine differences in the secondary structure, hydrogen bonds, and weakly polar interactions. CLN025 was synthesized by microwave-assisted solid phase peptide synthesis with N(alpha)-Fmoc protected amino acids. The VCD spectra displayed a (-,+,-) pattern with bands at 1640 to 1656 cm(-1), 1667 to 1687 cm(-1), and 1679 to 1686 cm(-1) formed by the overlap of a lower frequency negative couplet and a higher frequency positive couplet. A maximum IR absorbance was observed at 1647 to 1663 cm(-1) with component bands at 1630 cm(-1), 1646 cm(-1), 1658 cm(-1), and 1675 to 1680 cm(-1) that are indicative of the beta-sheet, random meander, either random meander or loop and turn, respectively. These results are similar to the results of others, who examined the VCD spectra of beta-hairpins formed by (D)Pro-Xxx turns and indicated that observed pattern is typical of beta-hairpins.
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