Possibility for detecting 14 typical odorants occurring in drinking water by employing human odor-binding protein OBP2a

Environmental Sciences Europe

Table 2 Binding affinities of 14 odorants to OBP2a

Odorants		IC50 ^a (μmol/L)	K_i ^b (μmol/L)	RSD ^c (%)
2-Methylisoborneol	2-MIB	63.34 ± 0.24	43.89 ± 0.17	0.36
Geosmin	GSM	90.86 ± 0.02	63.06 ± 0.01	0.02
2-Isobutyl-3-methoxy pyrazine	IBMP	71.01 ± 0.32	48.36 ± 0.22	0.44
Bis(2-chloro-1-methylethyl) ether	DCIP	81.28 ± 0.48	56.00 ± 0.38	0.59
Dimethyl disulfide	DMDS	73.90 ± 0.45	50.72 ± 0.31	0.65
Dimethyl trisulfide	DMTS	59.93 ± 0.18	41.83 ± 0.13	0.26
2-Ethyl-4-methyl-1,3-dioxolane	2E4MDL	72.74 ± 0.24	51.29 ± 0.17	0.31
Hexanal	–	61.37 ± 0.50	41.49 ± 0.39	0.81
Heptanal	–	65.71 ± 0.38	43.87 ± 0.25	0.59
Benzaldehyde	–	57.88 ± 0.21	37.25 ± 0.14	0.32
2-Octenal	–	45.35 ± 0.23	29.91 ± 0.15	0.46
Decanal	–	46.86 ± 0.20	31.59 ± 0.13	0.38
β-Cyclocitral	–	51.38 ± 3.48	34.79 ± 2.36	7.07
Undecanal	–	95.60 ± 2.40	61.05 ± 1.53	2.52

^a The concentration of ligand halving the initial fluorescence intensity;
^b dissociation constants between OBP2a and target odorants;
^c the relative standard deviations (RSD) of dissociation constants for all odorants