Mimicking Integrated Functions of “Molecular Space” in Biological Systems by Using Crystalline Cavities Consisting of Short Peptides

Abstract

The intelligent use of “molecular space” is an important feature of biological functions, such as selective or efficient catalysis, molecular transfer, accurate molecular recognition, etc. Peptides provide various types of “molecular space” due to the varietyof functional groups and highly ordered structure, in which integrated functions are demonstrated, supported by, in some cases, adaptable structrual changes (such as induced fit) becasuse of their structural flexibility. In addition, correlation of several types of “molecular space,” through cooperative structural changes in the peptide framework, is key for environmental responsive functions of biological systems. These features of peptides could be applied to artificial systems in the design of functional solid materials. Crystalline materials are one of the easiest approaches to construct materials consisting of several units which correlate each other due to the structural regularity. Thus, until now, various crystalline nano-cavities (as was “molecular space”) consisting of short peptide moieties (hereafter “peptide crystalline nano-cavities”) have been reported, showing their potential for the design of artificial crystalline nano-cavities. Various features of biological systems, such as design properties and adaptable properties (such as induced fit), have been successfully mimicked in reported systems. Recently, dynamic features such as cooperative bindings have also been demonstrated using peptide crystalline cavities. These features could lead to catalysis supported by selective or efficient molecular capture as was “molecular space” in enzyme in near future. In this review, recent developments of peptide crystalline nano-cavities are overviewed.