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Epigallocatechin-3-gallate is an inhibitor of Na,K-ATPase by favoring the E1 conformation |
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| Authors: | Hideo Ochiai Kazuo Takeda Yoshikazu Tahara Kazuhiro Abe Shunsuke Noguchi Masumi Inoue Wolfgang Schwarz Masaru Kawamura |
| Affiliation: | a Department of Cell Biology, University of Occupational and Environmental Health, Iseigaoka, Yahatanishiku, Kitakyushu 807-8555, Japan b Department of Biochemistry, Kyorin University School of Medicine, Mitaka, Tokyo 181-8611, Japan c Department of Biophysics, Faculty of Science, Kyoto University, Oiwake, Kitashirakawa, Sakyo-ku, Kyoto 606-8502, Japan d Department of Cell and Systems Physiology, University of Occupational and Environmental Health, Kitakyushu 807-8555, Japan e Shanghai Research Center for Acupuncture and Medrians, Shanghai-Pudong 201203, China f Max-Planck-Institut fur Biophysik, Max-von-Laue-Str. 3, D-60438, Frankfurt am Main, Germany |
| Abstract: | Four catechins, epigallocatechin-3-gallate, epigallocatechin, epicatechin-3-gallate, and epicatechin, inhibited activity of the Na+,K+-ATPase. The two galloyl-type catechins were more potent inhibitors, with IC50 values of about 1 μM, than were the other two catechins. Inhibition by epigallocatechin-3-gallate was noncompetitive with respect to ATP. Epigallocatechin-3-gallate reduced the affinity of vanadate, shifted the equilibrium of E1P and E2P toward E1P, and reduced the rate of the E1P to E2P transition. Epigallocatechin-3-gallate potently inhibited membrane-embedded P-type ATPases (gastric H+,K+-ATPase and sarcoplasmic reticulum Ca2+-ATPase) as well as the Na+,K+-ATPase, whereas soluble ATPases (bacterial F1-ATPase and myosin ATPase) were weakly inhibited. Solubilization of the Na+,K+-ATPase with a nonionic detergent reduced sensitivity to epigallocatechin-3-gallate with an elevation of IC50 to 10 μM. These results suggest that epigallocatechin-3-gallate exerts its inhibitory effect through interaction with plasma membrane phospholipid. |
| Keywords: | Epigallocatechin-3-gallate Na+,K+-ATPase Inhibition P-type ATPase Phospholipid |
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