Journal article
Probing the Conformation-Dependent Preferential Binding of Ethanol to Cationic Glycylalanylglycine in Water/Ethanol by Vibrational and NMR Spectroscopy
The journal of physical chemistry. B, v 121(23), pp 5744-5758
15 Jun 2017
PMID: 28530400
Featured in Collection : UN Sustainable Development Goals @ Drexel
Abstract
The conformational propensity of amino acid residues is determined by an intricate balance of peptide-solvent and solvent-solvent interactions. To explore how the systematic replacement of water by a cosolvent affects the solvation of both the amino acid backbone and side chains, we performed a combined vibrational spectroscopy and NMR study of cationic glycylalanylglycine (GAG) in different ethanol/water mixtures of between 0 and 42 mol percent ethanol. Classical model peptide N'-methylacetamide was used as a reference system to probe solvent-induced spectroscopic changes. The alanine residue of GAG in water is known to exhibit a very high propensity for polyproline II (pPII). Adding up to 30 mol % ethanol at room temperature leads only to minor changes in the Ramachandran distribution of alanine, which mostly changes within the individual conformational subspaces. A further increase in the ethanol fractions leads to a destabilization of pPII and a stabilization of beta-strand conformations. At higher temperatures, different degrees of enthalpyentropy compensations lead to a much stronger influence of ethanol on the peptides conformational distribution. Ethanol-induced changes in chemical shifts and amide I wavenumbers strongly suggest that ethanol replaces water preferentially in the solvation shell of the polar C-terminal peptide group and of the alanine side chain, whereas the N-terminal group remains mostly hydrated. Furthermore, we found that ethanol interacts more strongly with the peptide if the latter adopts beta-strand conformations. This leads to an unusual positive temperature coefficient for the chemical shift of the C-terminal amide proton. Our data suggests a picture in which GAG eventually accumulates at waterethanol interfaces if the ethanol fractions exceed 0.3, which explains why the further addition of ethanol eventually causes self-aggregation and the subsequent formation of a hydrogel.
Metrics
Details
- Title
- Probing the Conformation-Dependent Preferential Binding of Ethanol to Cationic Glycylalanylglycine in Water/Ethanol by Vibrational and NMR Spectroscopy
- Creators
- David DiGuiseppi - Drexel Univ, Dept Chem, Philadelphia, PA 19104 USABridget Milorey - Drexel Univ, Dept Chem, Philadelphia, PA 19104 USAGabrielle Lewis - Drexel Univ, Dept Biol, Philadelphia, PA 19104 USANina Kubatova - Goethe University FrankfurtStefanie Farrell - Drexel Univ, Dept Chem, Philadelphia, PA 19104 USAHarald Schwalbe - Goethe University FrankfurtReinhard Schweitzer-Stenner - Drexel University
- Publication Details
- The journal of physical chemistry. B, v 121(23), pp 5744-5758
- Publisher
- American Chemical Society; Washington, DC
- Number of pages
- 15
- Grant note
- Department of Chemistry at Drexel University
- Resource Type
- Journal article
- Language
- English
- Academic Unit
- Biochemistry and Molecular Biology; [Retired Faculty]; Chemistry
- Web of Science ID
- WOS:000403731400008
- Scopus ID
- 2-s2.0-85021680118
- Other Identifier
- 991019168006704721
UN Sustainable Development Goals (SDGs)
This publication has contributed to the advancement of the following goals:
InCites Highlights
Data related to this publication, from InCites Benchmarking & Analytics tool:
- Collaboration types
- Domestic collaboration
- International collaboration
- Web of Science research areas
- Chemistry, Physical