Derivatisation of cycloamyloses and catalysis

However, for the last quarter of a century, the consensus amongst enzymo-logists, largely through an influential review by Jencks, has been that most of the catalytic power of those enzymes not employing complex cofactor chemistry derives from transition state interactions between parts of the substrate and parts of the enzyme not involved in covalency changes, and that therefore small-molecule mimics of these enzymes will only ever produce small accelerations. A rate enhancement even of 7000 is unimpressive when that of real glycosidases is 10.  

Much more successful has been the tailor-making of catalysts combining cyclodextrins with transition metals or other heavy elements with multiple valencies. The cyclodextrins envelope labile catalytic centres and/or provide a binding site. Enzyme mimicry is more plausible where the specialist chemistry of a cofactor is crucial. Thus, a 2 2 -ditelluro-bis-cycloheptaamylose in its oxidised form had a kcmlKm for oxidation of 3-carboxy-4-nitrobenzenethiol only 600-fold less than that of glutathione peroxidase oxidising glutathione -but even here the mimicry is not close, as the enzyme uses a selenium, not a tellurium, cofactor. 

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