Sweetness model

An alternative view (123) is that no single model can adequately explain why any given compound is sweet. This hypothesis derives from several features. First, there is the observation that all carbohydrates having a critical ratio of OH to C are sweet tasting. In other words, there are no stmctural constraints to the sweetness of carbohydrates. Second, not all sweeteners can be fit to the same SAR model. Rather, some fit one, others fit another. Third, studies on the transduction mechanisms of sweetness suggest more than a single mechanism for sweet taste, implying multiple receptors for sweeteners. 

Koenigs-Knorr reaction of, 990 molecular model of, 119, 126, 985 mutarotation of, 985-986 pentnacetyl ester of, 988 pentamethyl ether of, 988 pyranose form of, 984-985 pyruvate from. 1143-1150 reaction with acetic anhydride, 988 reaction with ATP, 1129 reaction with iodomethane, 988 sweetness of. 1005 Williamson ether synthesis with. 988... 

Substituent effect, additivity of, 570 electrophilic aromatic substitution and, 560-563 summary of. 569 Substitution reaction, 138 Substrate (enzyme), 1041 Succinic acid, structure of, 753 Sucralose, structure of. 1006 sweetness of, 1005 Sucrose, molecular model of. 999 specific rotation of, 296 structure of, 999 sweetness of, 1005 Sugar, complex, 974 d, 980 L, 980... 

Dicoumarol is found in sweet clover and can cause hemorrhaging in cattle because of its anticoagulant action. It acts as a vitamin K antagonist and has served as a model for the development of warfarin and related anticoagulant rodenticides. 

The Noyori procedure was applied to a total synthesis of baiyunoside, a sweet principle, using 2,3,4-tri-<9-benzyl-D-xylopyranosyl fluoride (18 see Table 1), and a synthesis of glycotriosyl ceramide. A model experiment for the synthesis, using 18, showed a solvent dependence for the a ratio of the products. In this case, the use of acetonitrile, oxolane, or ether gave the a anomer (1,2-a.v), and the use of toluene or hexane gave the P anomer (1,2-trans), preponderantly. 

However, the model is defined such that the terms ir, a, fi, and a may all be measures of different types of receptor-sweetener binding. These all reflect the probability of that event s occurring, while, at the same time, the probability of the sweetener s reaching its receptor, and that of the receptor complex s undergoing the response-eliciting reaction, may both be unity The sole criterion for the sweet-taste response would thus require the formation of the proper sweetener-receptor complex. The validity of such a hypothesis has yet to be proved. " ... 

The structural simplicity of hernandulcin and its intense sweet taste offer an excellent model for further studies on the structure-sweetness relationship. 

The binding specificity of d-[ C]glucose by the taste-papillae membranes, compared to that of control membranes isolated from epithelial tissue, has been confirmed in two studies. One inherent problem in the approach is that the stimuli, primarily carbohydrate sweeteners, are not ideal model compounds to use, as they are not active at low concentrations and do not show sufficiently high binding-constants. The use of other stimulus compounds that are at least several hundred times sweeter than sucrose, such as saccharin, dihydrochalcone sweeteners, dipeptide sweeteners, stevioside, perillartine and other sweet oximes, the 2-substituted 5-nitroanilines, and... 

It has been proposed " that the mechanism(s) of action of gymnemic acids and ziziphins is a biphasic, model-membrane penetration-process. The model suggested that the modifier molecules interact first with the receptor-cell plasma-membrane surface. It was postulated that this initial interaction involves a selective effect on taste perception, including the transduction and quality specification of the sweet stimuli, and selective depression of sweetness perception. Following the initial interaction, the modifier molecules interact with the membrane-lipid interior to produce a general disruption of membrane function and a nonselective effect on taste... 

Skelton, D., Clements, B., McCandless, T.E., Hood, C. Aulbach, S., Daview, R,. Boyer, L.P. 2003. The Buffalo Head Hills kimberlite province, Alberta. In Kjarsgaard, B.A. (ed.). Slave Province and Northern Alberta Field Trip Guidebook. Geological Survey of Canada, Miscellaneous Publication G-293. Skinner, E.M.W. Marsh, J.S. 2004. Distinct kimberlite pipe classes with contrasting eruption processes. Lithos, 76, 183-200. Sweet, A.R., Boyce, K,. Eccles, D.R. In prep. Palynological constraints on kimberlite emplacement models chronostratigraphy of host rock and clastic xenoliths, Buffalo Head Hills, Alberta. 

During work on a series of aspartyl dipeptides containing ACC 71 (vide supra, Eq. (28), Sect. 4) at the carboxyl terminus, it was reported that dispartame Asp-ACC-OMe had a distinct sweet taste [302] and that the corresponding n-propyl ester had 250-300 times the sweetness of sucrose [303]. However, replacement of phenylalanine by 2,3-methanophenylalanine gave tasteless analogues of aspartame [293, 304], and some dimethyl-ACC 214 (methanovaline) and tri-methyl-ACC 215 aspartame analogues [Asp-(Me)n-ACC-OMe] have a bitter taste. These taste properties, which depend on the number and position of the methyl substituents, have been explained on the basis of topochemical models thus, a L-shaped conformation of the dipeptide is necessary for sweet taste, Eq. (86) [3051. 

Hirai, M. Y., Suzuki, H., Yamazaki, M. and Saito, K. 2000. Biochemical andpatrial molecular characterization of bitter and sweet form of Lupinus angustifolius, an experimental model for study of molecular regulation of quinolizidine alkaloids biosynthesis. Chemistry and Pharmacy. Bulletin, 48 1458-1461. 

The experimental data suggest that sweetness and bitterness are recognized at the same receptor. Furthermore, the receptor discriminates between bitter and sweet tastes based upon differences in functional unit combination. A new taste receptor model is proposed and presented. 

An interesting experiment using the model of aspartame (Figure 1) was carried out in 1985. Combinations of two or three different molecules were prepared to examine whether or not sweetness could be produced in the same system as aspartame. The... 

---