Evaluating the Reduced Hydrophobic Taste Sensor Response of Dipeptides by Theasinensin A by Using NMR and Quantum Mechanical AnalysesReportar como inadecuado




Evaluating the Reduced Hydrophobic Taste Sensor Response of Dipeptides by Theasinensin A by Using NMR and Quantum Mechanical Analyses - Descarga este documento en PDF. Documentación en PDF para descargar gratis. Disponible también para leer online.

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.



Autor: Jian Guo, Naoto Hirasaki, Yuji Miyata, Kazunari Tanaka, Takashi Tanaka, Xiao Wu, Yusuke Tahara, Kiyoshi Toko, Toshiro Matsui

Fuente: http://plos.srce.hr/



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