Sensory evidence for olfactory receptors with opposite chiral selectivity.
Human odor responses to alpha-ionone enantiomers were measured by psycho-physical methods. Surprisingly, subjects' relative sensitivities for these enantiomers were found to diverge widely, some subjects being much more sensitive to (+) than to (-) and vice versa. In 63 subjects the (+)/(-) threshold concentration ratio varied over 4 orders of magnitude. Nine subjects with extreme (+)/(-) ratios were further tested several times over a 7-month period and retained stable ratios. These same nine subjects, when tested for threshold sensitivity to carvone enantiomers, showed (+)/(-) ratios that varied only in a narrow range and did not correlate with their ionone ratios. It is suggested that odor discrimination of alpha-ionone enantiomers involves at least two receptor types of opposite chiral selectivity and that their distribution varies independently in the human population.
Polak
E H
EH
Université Paris VI, Laboratoire de neurophysiologie Comparée, France.
Fombon
A M
AM
Tilquin
C
C
Punter
P H
PH
D000293:Adolescent; D000328:Adult; D002628:Chemoreceptor Cells / Q000502:physiology*; D006801:Humans; D008875:Middle Aged; D009812:Odorants; D009830:Olfactory Bulb / Q000502:physiology; D009831:Olfactory Mucosa / Q000294:innervation*; D011601:Psychophysics; D012684:Sensory Thresholds; D012903:Smell / Q000502:physiology*; D013237:Stereoisomerism