VCD spectroscopic properties of the b-hairpin forming miniprotein CLN025 in various solvents

• Published in: Biopolymers 2010-05, Vol.93 (5), p.442-450
• Main Authors: Hatfield, Marcus P D, Murphy, Richard F, Lovas, Sandor
• Format: Article
• Language: English
• ISSN: 0006-3525
• DOI: 10.1002/bip.21356

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 -hairpin. In this study, the VCD spectral features of a decapeptide, YYDPETGTWY (CLN025), which forms a stable -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 -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-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 -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 -hairpins formed by DPro-Xxx turns and indicated that observed pattern is typical of -hairpins.