Double Ion Trap Laser Spectroscopy of Alkali Metal Ion Complexes with a Partial Peptide of the Selectivity Filter in K+ Channels─Temperature Effect and Barrier for Conformational Conversions
| Autor: | Keisuke Hirata, Masaaki Fujii, James M. Lisy, Yukina Suzuki, Shun-ichi Ishiuchi |
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| Rok vydání: | 2021 |
| Předmět: | |
| Zdroj: | The Journal of Physical Chemistry A. 125:9609-9618 |
| ISSN: | 1520-5215 1089-5639 |
| DOI: | 10.1021/acs.jpca.1c06440 |
| Popis: | Potassium ion channels selectively permeate K+, as well as Rb+ and Cs+ to some degree, while excluding Na+ and Li+. Conformations of alkali metal complexes of Ac-Tyr-NHMe, a model peptide of the selectivity filter in a K+ channel, were previously found to correlate with the permeability of alkali metal ions to a K+ channel by cold ion trap infrared spectroscopy. With an additional temperature-controlled ion trap, we examined the conformations of the alkali metal complexes, allowing the ions to collide with a He buffer gas at different temperatures, prior to spectroscopic investigation. The conformational distribution of the K+-peptide complex shows the most significant variation with temperature, which suggests that this complex has more flexibility when complexed with K+ and suggests lower barrier heights than other metal-peptide complexes. The variability of the conformational distribution with temperature for the ions follows the same order of ion permeability of a K+ channel. This work demonstrates that the additional temperature-controlled ion trap is a powerful tool to explore the conformational landscape of flexible molecular systems. |
| Databáze: | OpenAIRE |
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