Metallobiosites modelling

On a more sophisticated level, functional metallobiosite models may also, in principle, be prepared in the same conceptual fashion as applied to purely organic systems. Such systems are much more challenging and their success depends on the extent to which the enzyme activity is related to the nature of the metal first coordination sphere. It becomes, in general, almost exponentially more difficult to control the metallobiosite environment, the further the departure from the metal ion and its primary coordination sphere. 

A cascade receptor is a host that binds one of more metal ions which, in turn, bind anions. They are of interest in the modelling of biological metal-based active sites — metallobiosites. 

Hill introduced two useful definitions for model compounds of metalloproteins, — speculative models and corroborative models, Speculative models are prepared when the structure of the microenvironment of the metallobiosite is unknown and the objective is to reproduce some physico-chemical property of the system in a small molecule complex. When the structure of the metallobiosite is known a corroborative model can be prepared. This is usually a small molecule complex in which the environment of the metal is reproduced as accurately as possible. It then becomes possible to determine whether the observed properties of the metal in the protein are dominated by the first coordination sphere and can give insights into the relationship between structural features of the metallobiosite and its physical properties. 

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