Abstract
The catalytic activity, expressed as K m and V max values, of 16 enzymes of practical interest with the macromolecular coenzymes poly(ethylene glycol)-N 6-(2-aminoethyl)-NAD + and poly(ethylene glycol)-N 6-(2-aminoethyl)-NADP + and their low molecular weight precursors N 6-(2-aminoethyl)-NAD + and N 6-(2-aminoethyl)-NADP +, was investigated. The enzymes examined are of direct interest for organic synthesis (i.e. alcohol dehydrogenase from yeast, horse liver, or Thermoanaerobium brockii, lactic dehydrogenase, and several hydroxysteroid dehydrogenases) or are used for the regeneration of NAD +, NADP +, NADH, or NADPH (i.e. glutamate dehydrogenase from liver or Proteus, formate dehydrogenase, glucose dehydrogenase, and malic enzyme). The cycling efficiency of poly(ethylene glycol)-N 6-(2-aminoethyl)-NADP + was examined with coupled-enzymes or coupled-substrates systems. Poly(ethylene glycol)-N 6-(2-aminoethyl)-NAD + and, even more so, poly(ethylene glycol)-N 6-(2-aminoethyl)-NADP + were excellent coenzymes with several dehydrogenases. In addition, the coenzymatic properties of N 6-(3-sulfonatopropyl)-NAD +, an NAD + derivative carrying a strong anionic group, were compared with those of the newly synthesized N 6-(2-hydroxy-3-trimethylammonium propyl)-NAD +, an NAD + derivative carrying a strong cationic group. It was expected that the presence of the sulfonic or quaternary ammonium group would enhance the residence time of the coenzyme inside continuous-flow reactors if membranes with anionic or cationic groups, respectively, were used.
Published Version
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