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Evaluating the Reduced Hydrophobic Taste Sensor Response of Dipeptides by Theasinensin A by Using NMR and Quantum Mechanical Analyses.
- Source :
- PLoS ONE, Vol 11, Iss 6, p e0157315 (2016)
- Publication Year :
- 2016
- Publisher :
- Public Library of Science (PLoS), 2016.
-
Abstract
- The current study demonstrated that theasinensin A (TSA) had a potential to form the complex with hydrophobic Trp-containing dipeptides, and to reduce their membrane potential by artificial-lipid membrane taste sensor. At a 1:3 molar ratio of the 6 Trp-containing dipeptides together with TSA, we observed a significant chemical shift of the protons of the dipeptides (Δδ) to a high magnetic field, when analyzed using 1H-nuclear-magnetic resonance (NMR) spectroscopy. The Δδ values were correlated with the hydrophobicity (log P) of the dipeptides and significant correlations were obtained (P = 0.022, R2 = 0.77); e.g., Trp-Leu with the highest log P value of 1.623 among the tested dipeptides showed the highest Δδ value of 0.105 ppm for the H7 proton of Trp-Leu, while less chemical shifts were observed in theasinensin B and epigallocatechin-3-O-gallate. Diffusion-ordered NMR spectroscopy revealed that the diffusion coefficient of 3 mM of Trp-Leu (7.6 × 10-11 m2/s) at a pulse field gradient in the range 0.05-0.3 T/m decreased in the presence of 3 mM TSA (6.6 × 10-11 m2/s), suggesting that Trp-Leu forms a complex with TSA. Quantum mechanical calculations and rotating frame nuclear Overhauser effect-NMR spectroscopy provided configuration information on the geometry of the complex that Trp-Leu formed with TSA (1:1 complex) with a ΔG energy of -8.7 kJ/mol. A sensor analysis using artificial-lipid membranes demonstrated that the changes in membrane potential of 1 mM Trp-Leu (21.8 ± 1.3 mV) and Leu-Trp (5.3 ± 0.9 mV) were significantly (P < 0.001) reduced by 1 mM TSA (Trp-Leu, 13.1 ± 2.4 mV; Leu-Trp, 3.5 ± 0.5 mV; TSA alone, 0.2 ± 0.01 mV), indicating the effective suppression of hydrophobicity of dipeptides by TSA-formed complex.
Details
- Language :
- English
- ISSN :
- 19326203
- Volume :
- 11
- Issue :
- 6
- Database :
- Directory of Open Access Journals
- Journal :
- PLoS ONE
- Publication Type :
- Academic Journal
- Accession number :
- edsdoj.295ccd7d2d1f4bf5b9533ff040b9d3df
- Document Type :
- article
- Full Text :
- https://doi.org/10.1371/journal.pone.0157315