pH-Dependent Inhibition of the Human Bitter Taste Receptor hTAS2R16 by a Variety of Acidic Substances

Some acidic peptides are known to reduce bitterness, but the detailed mechanism underlying this effect remains to be elucidated. In this study, we analyzed the effects of acidic dipeptides on the inhibition of the human bitter taste receptor hTAS2R16. Calcium imaging analysis of HEK293T cells expressing hTAS2R16 revealed that their response to the bitter tastant salicin was reduced in the presence of acidic dipeptides. A similar inhibitory effect was observed in a variety of other acids. The inhibition depended on the pH values resulting from the addition of acids but not on their concentrations. Our results suggest that the inhibition of the bitter taste receptors can be attributed to the bitterness-masking effect of the acidic dipeptides and that acidic pH may be one of the critical factors responsible for this sensory event.