Homogeneous Polymer Biocatalysts

Fabrication of Macromolecules with Strong Affinities lor Ligands 

Thus one might expect flexible, water-soluble synthetic polymers with suitable side chains to show affinities for small molecules. We have examined, over several decades, the binding ability of poly(vinylpyrrolidone), polyvinylpyridine, polylysine, polyacrylamide, poly(isopropylacrylamide), poly(vinylimidazole), poly(vinylmethyloxazolidi-none), poly(vinylmethyloxazolidinone-vinylimidazole), poly(vinylpyrrolidone-vinyli-midazole), poly(vinylpyrrolidone-vinyl alcohol), poly(vinylpyrrolidone-maleic anhydride), poly(vinylmethyloxazolidinone-maleic anhydride), and poly(2-methylami-noethyl methylacrylate-methacrylic acid). Other investigators have studied similar synthetic polymers [5-12], In our experience no water-soluble polymer binds small molecules with an avidity comparable to serum albumin. 

These polymers have high intrinsic viscosities (e.g. about 22 ml g-1 for polyvinylpyrrolidone), which indicate that the macromolecules are swollen and extended in water. In contrast, serum albumin, with an intrinsic viscosity near 4 ml g-1, must be relatively compact. Such a relatively compact conformation might be obtained with a water-soluble polymer by introducing cross-linkages or by using a highly branched matrix. Indeed, the latter has proved to be particularly fruitful. 

---