Biochemists have confirmed the sweet taste of heavy water and discovered the receptor responsible for perception of it — it was TAS1R2/TAS1R3 — the main sweet taste receptor in humans (mice incapable of feeling the sweetness of heavy water). Using molecular dynamic modeling, scientists have found that in heavy water the receptor proteins become more rigid and organized. A Preprint of the article published on the website bioRxiv.
Pure water itself has neither taste nor smell. The same features scientists had expected and the heavy water isotope analogue of water, in which instead of protium (the most common hydrogen isotope) is deuterium. Deuterium, in contrast, protium, has a neutron, which increases its weight by almost half, which demonstrates some differences from the normal water: heavy water is ten percent denser, and its melting point by 3.82 degrees higher because of stronger hydrogen bonds. The pH of heavy water(or pD in this case) at 25 degrees Celsius, slightly above — 7,41.
In living organisms, the replacement of a significant amount of light water to heavy leads to disruption of metabolism, but in small amounts it is harmless — in the body of the deuterium already present: one atom of deuterium has 6400 atoms of protium. Heavy water mixed with thelocality water (another isotope of water with oxygen-18) used for medical purposes to monitor metabolism on the kinetics of leaching of isotopes from the body.
A matter of taste of heavy water rose from its opening in 1931 — then the scientists first appreciated its sweet taste. However, in 1935 had published a small article in which two scientists, Urey and Failla, are unable to distinguish between distilled and pure heavy water, after which the matter was considered closed. In 1975, scientists have once again returned to study differences between heavy water and ordinary — not all subjects were able to distinguish between ateriovenous and regular water, but the average taste properly chosen in eight cases out of ten, smell to distinguish the water it does not work.
Over the past twenty years, scientists have established the basic taste receptor in humans to determine the sweet taste is a heterodimer G-protein (TAS1R2/TAS1R3). Sweet taste as bitter, is determined by receptors through interaction “lock”, the main feature of sweet is the position of hydrogen bonds in the right place, but it has low specificity, and therefore sweet felt completely different chemicals.