Görbitz C H
Acta Chem Scand B. 1987 Feb;41(2):87-92. doi: 10.3891/acta.chem.scand.41b-0087.
The crystal and molecular structure of the hydrochloride salt of the peptide sweetener aspartame (alpha-L-Asp-L-Phe methyl ester) has been determined at 120 K using 3877 reflections with I greater than 2.5 sigma I. Space group P2(1)2(1)2(1), cell dimensions a = 6.768(1), b = 9.796(1) and c = 26.520(3) A; final R factor 0.033. While the N-terminal L-Asp group in the structure of aspartame itself forms a six-membered ring with an intramolecular hydrogen bond between the carboxylate and the protonated amino terminus, the corresponding group in the hydrochloride adopts a completely different conformation with a weak intramolecular hydrogen bond between the carboxyl group and the N atom of the L-Phe residue. The L-Phe methyl ester moiety is rather similar in the two structures. Of the many possible conformations of aspartame, only one may be expected to function as a substrate at the receptor site for sweet taste, and a proposal is made for this active conformation.
已在120K下使用3877个I大于2.5σI的反射确定了肽甜味剂阿斯巴甜（α-L-天冬氨酰-L-苯丙氨酸甲酯）盐酸盐的晶体和分子结构。空间群P2(1)2(1)2(1)，晶胞参数a = 6.768(1)，b = 9.796(1)和c = 26.520(3) Å；最终R因子为0.033。在阿斯巴甜自身结构中，N端的L-天冬氨酰基团形成一个六元环，在羧酸盐和质子化氨基末端之间存在分子内氢键，而在盐酸盐中相应基团采用完全不同的构象，在羧基和L-苯丙氨酸残基的N原子之间存在弱分子内氢键。L-苯丙氨酸甲酯部分在两种结构中相当相似。在阿斯巴甜众多可能的构象中，预计只有一种可能作为甜味受体位点的底物起作用，并提出了这种活性构象。
