Gustatory responses of non-human primates to dipeptide derivatives or analogues, sweet in man

Dipeptide derivatives or analogues, sweet in man, can be divided into three classes according to their gustatory responses in primates: (i) dipeptides which are sweet to all primates (prosimians, New World simians and Old World simians), such as alitame or l-aspartyl-d-alanine propyl ester (class I); (ii) dipeptides which are sweet to prosimians and Old World simians, but not to New World simians, such as l-aspartyl-(R)-α-methylphenethylamine or l-aspartyl-l-(O-tert-butyl)serine methyl ester (class II); and, (iii) compounds which are sweet only to Old World simians, but not to prosimians and New World simians, such as aspartame (class III). Analysis of these results by means of the multipoint attachment (MPA) theory of sweetness reception (Nofre & Tinti, 1996) leads to the conclusion that the seven basic recognition sites of the sweetness receptor, as inferred from the MPA theory, are (i) in prosimians: Asp-1 or Glu-1, Lys-2, Asp-3 or Glu-3, Thr-4, Ala-5 or Ser-5, Thr-6, Thr-7; (ii) in New World simians: Asp-1 or Glu-1, Lys-2, Asp-3 or Glu-3, Thr-4, Ala-5 or Ser-5, Ala-6 or Ser-6, Thr-7; and, (iii) in Old World simians: Asp-1 or Glu-1, Lys-2, Asp-3 or Glu-3, Thr-4, Thr-5, Thr-6, Thr-7.