ISSN:
0006-3525
Keywords:
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
In order to investigate the conformational preferences to elicit tastes, conformational free energy calculations using an empirical potential (ECEPP/2) and the hydration shell model were carried out on the L-aspartyl dipeptide methyl esters, L-+HAsp--L-Xaa-OMe, in the hydrated state, where Xaa includes sweet (Phe, Tyr, Met, and Gly), bitter (Ala, Trp, Val, Leu, and Ile), and tasteless (Ser, Thr, and Abu) residues. The refined preferred conformation of the Phe dipeptide (aspartame) with side chain χ21 conformation g- is g-Fg- in the hydrated state, which is consistent with the structure deduced from 1H-nmr experiments. Irrespective of the Xaa and taste, all the dipeptides have the same conformation for the Asp residue, which is attributable to the hydrogen bond between protonated amino hydrogen and carboxylate oxygen and the favored hydration of the carboxylate group. This implies that the L-aspartyl residue is a necessary factor for the dipeptides to be sweet not a sufficient factor. The computed conformational preferences for sweet, bitter, and tasteless dipeptides in the hydrated state indicate to us that the conformation about the N—Cα bond of the Xaa residue, i.e., the orientation of the hydrophobic moiety with respect to the AH/B functionalities in the aspartyl moiety, seems to be crucial to elicit the tastes. In addition, the hydrophobicity and the size of the Xaa residue are found to play a major role in determining the tastes. These well accord with the related works reported previously. © 1994 John Wiley & Sons, Inc.
Additional Material:
3 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/bip.360340807
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