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Role of Aromatic Cross-Links in Structure and Dynamics of Model Three-Stranded β-Sheet Peptides

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posted on 19.06.2018 by David Scheerer, Heng Chi, Dan McElheny, Ayesha Samer, Timothy A. Keiderling, Karin Hauser
A series of closely related peptide sequences that form triple-strand structures was designed with a variation of cross-strand aromatic interactions and spectroscopically studied as models for β-sheet formation and stabilities. Structures of the three-strand models were determined with NMR methods and temperature-dependent equilibrium studies performed using circular dichroism and Fourier transform infrared spectroscopies. Our equilibrium data show that the presence of a direct cross-strand aromatic contact in an otherwise folded peptide does not automatically result in an increased thermal stability and can even distort the structure. The effect on the conformational dynamics was studied with infrared-detected temperature-jump relaxation methods and revealed a high sensitivity to the presence and the location of the aromatic cross-links. Aromatic contacts in the three-stranded peptides slow down the dynamics in a site-specific manner, and the impact seems to be related to the distance from the turn. With a Xxx-DPro linkage as a probe with some sensitivity for the turn, small differences were revealed in the relative relaxation of the sheet strands and turn regions. In addition, we analyzed the component hairpins, which showed less uniform dynamics as compared to the parent three-stranded β-sheet peptides.

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We gratefully acknowledge financial support by the Deutsche Forschungsgemeinschaft (SFB 969, A2 to K.H.), the Center of Applied Photonics Konstanz (CAP to K.H.), National Science Foundation of China (NSFC 21503087 to H.C.) and Alexander von Humboldt Foundation Research Award (to T.A.K.).

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Copyright @ American Chemical Society

Citation

Scheerer, D., Chi, H., McElheny, D., Samer, A., Keiderling, T. A. and Hauser, K. Role of Aromatic Cross-Links in Structure and Dynamics of Model Three-Stranded beta-Sheet Peptides. Journal of Physical Chemistry A. 2018. 122(2): 543-553. 10.1021/acs.jpca.7b10190.

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American Chemical Society

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en_US

issn

1089-5639

Issue date

15/12/2017

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