Enzyme-mimicking polymers

Leonhardt, A. Mosbach, K. Enzyme-mimicking polymers exhibiting specific substrate binding and catalytic functions. React. Polym., Ion Exch., Sorbents 1987, 6, 285-290. 

Lewis-Acid Catalyzed. Recently, various Lewis acids have been examined as catalyst for the aldol reaction. In the presence of complexes of zinc with aminoesters or aminoalcohols, the dehydration can be avoided and the aldol addition becomes essentially quantitative (Eq. 8.97).245 A microporous coordination polymer obtained by treating anthracene- is (resorcinol) with La(0/Pr)3 possesses catalytic activity for ketone enolization and aldol reactions in pure water at neutral pH.246 The La network is stable against hydrolysis and maintains microporosity and reversible substrate binding that mimicked an enzyme. Zn complexes of proline, lysine, and arginine were found to be efficient catalysts for the aldol addition of p-nitrobenzaldehyde and acetone in an aqueous medium to give quantitative yields and the enantiomeric excesses were up to 56% with 5 mol% of the catalysts at room temperature.247... 

Stereoselective catalysis using biocatalysts (e.g. enzymes) and also of rationally designed small chiral molecules, deals essentially with the same principle the spatial and selective docking of guest molecules to a chiral host molecule to form complementary interactions to form reversible transient molecule associates (see the specific sections in this volume). The enantiomeric excess of a certain reaction and hence the result will be determined by the degree of chiral discrimination. Along the same theoretical lines the concepts of protein (enzyme, antibody, etc.) mimicks via imprinted" synthetic polymers should be mentioned and will be discussed further. 

In our model anti-idiotypic imprinting, we have chosen the medicinally interesting proteinase kallikrein as a model system. In the first step, a previously identified inhibitor [1] was used as the original template to prepare noncovalently an imprinted polymer. The polymer contains specific binding cavities mimicking the enzyme s active site. These cavities were then used in a second round of imprinting to... 

Therefore, 3 has been employed as a binding site functional monomer for imprinted polymers in several application areas like enantioselective separation, sensing layers, and catalytically active polymers mimicking natural enzyme action. 

Ion exchange polymers, mainly aniOTiic (e.g.. Nation ) but also catimiic (e.g., Tosflex) in character, are used to concentrate imiic analytes close to the electrode, mimicking somehow what happens at Hg in the stripping methods of analysis. These polymers are also used simply to entrap and tix a variety of ionic species, enzymes included, acting as the proper redox mediator. They are specifically described in Chap. 4. 

Current developments include the mimicking of nature (enzymes) for the synthesis of quite complex polymers like natural silk. Also, bacteria and plants are being modified to produce polymers of interest [18]. However, this can be expected to require polymer reaction engineering developments that are as yet difficult to foresee. 

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