日本东京大学Eiichi Nakamura团队报道了环糊精在尺寸敏感客体识别中的边缘结合。 相关研究成果于2021年4月7日发表在国际顶尖学术期刊《美国化学会杂志》。

环糊精（CDs）是具有空腔和两个边缘的甜甜圈状环状低聚糖。空腔中的包涵体结合一直是分子识别的经典模型，而边缘结合一直被忽略。

研究人员发现CDs除了利用空腔外，还可以利用单分子电子显微镜和石墨锥库作为固态基质进行络合，利用两个边缘的尺寸敏感结合识别客体。例如，通过对数千个单个样本的结构分析和数据的统计分析可以看出，结合其空腔和边缘结合能力，γ-CD可以识别半径在4到9之间的客体，其尺寸识别精度优于1。一个2.5ms分辨率的电子显微镜视频提供了尺寸识别过程的直接证据。

该数据表明，对于尺寸大于CD腔的客体，存在边缘结合模式，并说明了动态分子电子显微镜在破译超分子事件时空细节方面的独特应用。

附：英文原文

Title: Rim Binding of Cyclodextrins in Size-Sensitive Guest Recognition

Author: Hiroki Hanayama, Junya Yamada, Issei Tomotsuka, Koji Harano, Eiichi Nakamura

Issue&Volume: April 7, 2021

Abstract: Cyclodextrins (CDs) are doughnut-shaped cyclic oligosaccharides having a cavity and two rims. Inclusion binding in the cavity has long served as a classic model of molecular recognition, and rim binding has been neglected. We found that CDs recognize guests by size-sensitive binding using the two rims in addition to the cavity, using single-molecule electron microscopy and a library of graphitic cones as a solid-state substrate for complexation. For example, with its cavity and rim binding ability combined, γ-CD can recognize a guest of radius between 4 and 9 with a size-recognition precision of better than 1 , as shown by structural analysis of thousands of individual specimens and statistical analysis of the data thereof. A 2.5 ms resolution electron microscopic video provided direct evidence of the process of size recognition. The data suggest the occurrence of the rim binding mode for guests larger than the size of the CD cavity and illustrate a unique application of dynamic molecular electron microscopy for deciphering the spatiotemporal details of supramolecular events.

DOI: 10.1021/jacs.1c00651

Source: https://pubs.acs.org/doi/10.1021/jacs.1c00651