Alexander Jennifer M, Clark Joanna L, Brett Tom J, Stezowski John J
Department of Chemistry, University of Nebraska, Lincoln, NE 68588-0304, USA.
Proc Natl Acad Sci U S A. 2002 Apr 16;99(8):5115-20. doi: 10.1073/pnas.072647599. Epub 2002 Apr 9.
In a systematic study of molecular recognition of amino acid derivatives in solid-state beta-cyclodextrin (beta-CD) complexes, we have determined crystal structures for complexes of beta-cyclodextrin/N-acetyl-L-phenylalanine at 298 and 20 K and for N-acetyl-D-phenylalanine at 298 K. The crystal structures for the N-acetyl-L-phenylalanine complex present disordered inclusion complexes for which the distribution of guest molecules at room temperature is not resolvable; however, they can be located with considerable confidence at low temperature. In contrast, the complex with N-acetyl-D-phenylalanine is well ordered at room temperature. The latter complex presents an example of a complex in this series in which a water molecule is included deeply in the hydrophobic torus of the extended dimer host. In an effort to understand the mechanisms of molecular recognition giving rise to the dramatic differences in crystallographic order in these crystal structures, we have examined the intermolecular interactions in detail and have examined insertion of the enantiomer of the D-complex into the chiral beta-CD complex crystal lattice.
在一项关于固态β-环糊精（β-CD）配合物中氨基酸衍生物分子识别的系统研究中，我们测定了β-环糊精/N-乙酰-L-苯丙氨酸在298 K和20 K时以及N-乙酰-D-苯丙氨酸在298 K时配合物的晶体结构。N-乙酰-L-苯丙氨酸配合物的晶体结构呈现出无序包合物，其中室温下客体分子的分布无法分辨；然而，在低温下它们可以被相当准确地定位。相比之下，与N-乙酰-D-苯丙氨酸的配合物在室温下排列有序。后一种配合物是该系列配合物的一个例子，其中一个水分子深深地包含在延伸二聚体主体的疏水环中。为了理解导致这些晶体结构中晶体学有序性显著差异的分子识别机制，我们详细研究了分子间相互作用，并研究了D-配合物对映体插入手性β-CD配合物晶格的情况。
