4] Polymerizable NAD derivative and model enzyme reactor with recycling of polyethylene glycol-bound NAD

Abstract

This chapter describes methods for preparing a polymerizable nicotinamide adenine dinucleotide (NAD) derivative, NAD-N 6-[ N-( N-acryloyl-l -methoxycarbonyl-5-aminopentyl )propio-amide], and a polyethylene glycol-bound NAD derivative (PEG-NAD). The polymerizable NAD is a unique derivative that easily copolymerizes with other vinyl monomers, such as acrylamide, to give macromolecular NAD derivatives (polymeric NAD). Furthermore, various kinds of polymeric NAD may be obtained by copolymerization with different vinyl monomers in different molar ratios. To use macromolecular NAD derivatives in an enzyme reactor, it is necessary to understand the behavior of the system in which the reactions of dehydrogenases are coupled by the recycling of the NAD derivative. Methods for a theoretical analysis and the experimental operation of a model enzyme reactor containing lactate and alcohol dehydrogenases and PEG-NAD are also described in the chapter. It may be pointed out that the polymeric NAD derivatives, thus, obtained are heterogeneous mixtures of various polymer chains especially with respect to their molecular size. The cofactor activity of an NAD moiety on a polymer chain may depend on its position in the polymer chain and on the size of the polymer. These heterogeneities should be borne in mind when interpreting the properties of macromolecular NAD derivatives.