Evaluating the Reduced Hydrophobic Taste Sensor Response of Dipeptides by Theasinensin A by Using NMR and Quantum Mechanical Analyses.
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.
Department of Bioscience and Biotechnology, Division of Bioresource and Bioenviromental Sciences, Faculty of Agriculture, Graduated School of Kyushu University, 6-10-1 Hakozaki, Fukuoka, 812-8581, Japan.
Jian
J
Guo
Department of Bioscience and Biotechnology, Division of Bioresource and Bioenviromental Sciences, Faculty of Agriculture, Graduated School of Kyushu University, 6-10-1 Hakozaki, Fukuoka, 812-8581, Japan.
Naoto
N
Hirasaki
Nagasaki Agriculture and Forestry Technical Development Center, Higashisonogi Tea Research Station, 1414 Nakano-go, Higashisonogi, Nagasaki, 859-3801, Japan.
Yuji
Y
Miyata
Department of Nutrition, University of Nagasaki, 1-1-1 Manabino, Nagayo, Nagasaki, 851-2195, Japan.
Kazunari
K
Tanaka
Graduate School of Biochemical Sciences, Nagasaki University, 1-14 Bukyo-machi, Nagasaki, 852-8521, Japan.
Takashi
T
Tanaka
Graduate School of Information Science and Electrical Engineering, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka, 819-0395, Japan.
Xiao
X
Wu
Graduate School of Information Science and Electrical Engineering, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka, 819-0395, Japan.
Yusuke
Y
Tahara
Graduate School of Information Science and Electrical Engineering, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka, 819-0395, Japan.|Research and Development Center for Taste and Odor Sensing, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka, 819-0395, Japan.
Kiyoshi
K
Toko
Department of Bioscience and Biotechnology, Division of Bioresource and Bioenviromental Sciences, Faculty of Agriculture, Graduated School of Kyushu University, 6-10-1 Hakozaki, Fukuoka, 812-8581, Japan.|Research and Development Center for Taste and Odor Sensing, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka, 819-0395, Japan.
Toshiro
T
Matsui
D001578:Benzopyrans / Q000737:chemistry*; D015374:Biosensing Techniques / Q000295:instrumentation; D002392:Catechin / Q000031:analogs & derivatives* / Q000737:chemistry; D004058:Diffusion; D004151:Dipeptides / Q000737:chemistry*; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D008051:Lipid Bilayers / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D010636:Phenols / Q000737:chemistry*; D011485:Protein Binding; D011522:Protons; D011789:Quantum Theory; D012996:Solutions; D013649:Taste / Q000502:physiology; D013816:Thermodynamics
D001578:Benzopyrans; D004151:Dipeptides; D008051:Lipid Bilayers; D010636:Phenols; D011522:Protons; D012996:Solutions; C576796:epigallocatechin-3-O-gallate epigallocatechin dimer; C481298:theasinensin A; C509811:tryptophan-leucine; D002392:Catechin; C045651:epigallocatechin gallate