Abstract
Metalloenzymes are ingeniously designed natural catalysts that demonstrate specific substrate recognition, marked rate enhancement, and appropriate selection of reaction pathways under mild reaction conditions. Such enzymic functions are quite attractive from the view point of supramolecular chemistry and expected to be clarified on a molecular basis. If we consider a simple holoenzyme, then such a supramolecule is composed of a specific apoprotein and an additional cofactors, such as a coenzyme. An apoprotein generally provides a binding site for both specific coenzyme and substrate molecules, which is well separated from a bulk aqueous phase. It is quite important for the constitution of an artificial metalloenzyme to select a right kind of molecular system that is qualified for simulation of the characteristic physicochemical functions of an apoprotein. There are two possible approaches to the constitution of an artificial holoenzyme. One approach is to design a specific molecule that is capable of performing functions of both apoprotein and coenzyme. Another approach is to set up a supramolecular system by noncovalent combination of an appropriate apoprotein model with a coenzyme model. The concept for molecular design of artificial metalloenzymes is presented in this paper, and some examples are shown by using bilayer membranes, macrocyclic compounds, dendrimers, and natural proteins as apoprotein functions.
