Temussi model

The combination of several observations, using also flexible compounds, notably aspartame, whose solution structure had just been determined (Lelj et al., 1976), led to a detailed quasi-planar outline of the active site. The main features of this model can be summarized as follows (1) the active site of the receptor is a flat cavity with one side partially accessible even during the interaction with the agonist (2) the lower part of the cavity hosts the AH-B entity complementary to that of the sweet molecule (3) the upper part is hydrophobic and plays an important role in the case of very active sweeteners. This is often referred to as the "Temussi model" (Walters, 1995 Walters et al., 1986). Figure 4A shows the main contour of the active site hosting a model of aspartame in an extended conformation. 

Morini, Bassoli, and Temussi (2005) used computer-based methods (often referred to as in silico methods) to model the binding of sweet molecules to the sweet receptor. 

FIGURE 4 Three of the most popular indirect models of the active site of the sweet taste receptor. (A) Main contour ofthe active site proposed by Temussi and coworkers (Kamphuis et al., 1992 Temussi et al., 1978,1984,1991), hosting a molecular model of aspartame in an extended conformation. (B) A topological model, developed by Goodman et al. (1987). The L -shaped model and an L -shaped conformation of aspartame are superimposed. The hydrophobic side chain of Phe is denoted X, since it corresponds to the Kier s dispersion point. (C) 3D model of an idealized sweetener proposed by Tinti and Nofre (1991). Besides the AH-B entity, the model has six additional interaction points connected by a complex network of distances. 

Morini, G., and Temussi, P.A. (2005). Micro and macro models of the sweet receptor. Chem. Senses 30, 86-87. 

The latest model for the sweet-taste receptor, proposed by Piero Temussi of the University of Naples, postulates that there are four binding sites on the receptor that can be occupied independently. Small sweet-tasting molecules might bind to one of the sites, while a large molecule would bind to more than one site simultaneously. 

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