The binding site for neohesperidin dihydrochalcone at the human sweet taste receptor

BMC Structural Biology

Table 2 Effect of mutations predicted by molecular modeling on the activation of the sweet taste receptor by neohesperidin dihydrochalcone (NHDC) and aspartame (ASP)

variant	NHDC EC₅₀ (mM)	NHDC maximal signal (% of wt)	ASP EC₅₀ (mM)	ASP maximal signal (% of wt)
wt	0.1 ± 0.06	100	1.3 ± 0.1	100
S620A ^2.57	1.3 ± 0.5	55 ± 80	1.2 ± 0.3	64 ± 4
V621L^2.58	n.f.	---	n.f.	---
V621I ^2.58	>1	60 ± 14	1.9 ± 0.4	61 ± 1
F624L ^2.61	>1	35 ± 70	1.4 ± 0.2	21 ± 4
Y699L ^4.60	0.7 ± 0.1	83 ± 40	1.6 ± 0.4	78 ± 9
Y699F ^4.60	0.6 ± 0.4	72 ± 17	1.2 ± 0.3	56 ± 2
T724L ^5.37	0.5 ± 0.3	58 ± 60	1.5 ± 0.2	69 ± 2
R725M ^5.38	1.3 ± 0.4	64 ± 14	1.5 ± 0.7	56 ± 1
S726A ^5.39	0.9 ± 0.3	60 ± 50	0.9 ± 0.3	50 ± 2
L800F^7.38	0.2 ± 0.1	91 ± 70	1.2 ± 0.3	90 ± 1
C801I ^7.39	1.6 ± 0.7	70 ± 13	1.2 ± 0.5	50 ± 9
C801L^7.39	n.f.	---	n.f.	---
G804A ^7.42	1.3 ± 0.5	53 ± 10	1.6 ± 0.2	44 ± 1
G804V ^7.42	n.r.	---	1.3 ± 0.3	21 ± 2

Receptor variants that affect the NHDC response are shown in bold. Values are given as average over at least three independent experiments ± SD. n.f. no response to any tested sweetener, n.r. no response to neohesperidin dihydrochalcone up to highest tested concentration (6 mM), but responses to other sweeteners. (>), EC₅₀ not calculable because saturation is not reached (Additional file 2).

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