Hydrogen to deuterium isotopic substitution has only a minor effect on physical and chemical properties of water and, as such, is not supposed to influence its neutral taste. Here we conclusively demonstrate that humans are, nevertheless, able to distinguish D2O from H2O by taste. Indeed, highly purified heavy water has a distinctly sweeter taste than same-purity normal water and adds to perceived sweetness of sweeteners. In contrast, mice do not prefer D2O over H2O, indicating that they are not likely to perceive heavy water as sweet. HEK 293T cells transfected with the TAS1R2/TAS1R3 heterodimer and chimeric G-proteins are activated by D2O but not by H2O. Lactisole, which is a known sweetness inhibitor acting via the TAS1R3 monomer of the TAS1R2/TAS1R3, suppresses the sweetness of D2O in human sensory tests, as well as the calcium release elicited by D2O in sweet taste receptor-expressing cells. The present multifaceted experimental study, complemented by homology modelling and molecular dynamics simulations, resolves a long-standing controversy about the taste of heavy water, shows that its sweet taste is mediated by the human TAS1R2/TAS1R3 taste receptor, and opens way to future studies of the detailed mechanism of action.

中文翻译：

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重水的甜味

氢到氘的同位素取代对水的物理和化学性质影响很小，因此，不应影响其中性味。在这里，我们最终证明，人类仍然能够通过口味区分D2O和H2O。的确，高纯度重水比同等纯度的普通水具有明显的甜味，并增加了甜味剂的甜度。相反，小鼠不喜欢D2O而不是H2O，这表明它们不太可能将重水视为甜食。用TAS1R2 / TAS1R3异二聚体和嵌合G蛋白转染的HEK 293T细胞被D2O激活，但未被H2O激活。Lactisole是一种已知的通过TAS1R2 / TAS1R3的TAS1R3单体起作用的甜味抑制剂，可在人体感官测试中抑制D2O的甜味，以及D2O在表达甜味受体的细胞中引起的钙释放。当前的多方面实验研究，通过同源性建模和分子动力学模拟的补充，解决了关于重水味道的长期争论，表明其甜味是由人TAS1R2 / TAS1R3味觉受体介导的，为将来的研究开辟了道路详细的动作机制。