Preparation and Coenzymic Activity of Soluble Polyethyleneimine‐Bound NADP+ Derivatives

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Abstract
Alkylation at N-1 of the NADP+ adenine ring with 3,4-epoxybutanoic acid gave 1-(2-hydroxy-3-carboxypropyl)-NADP+. Enzymic reduction of the latter, followed by alkaline Dimroth rearrangement and enzymic reoxidation, gave N6-(2-hydroxy-3-carboxypropyl)-NADP+. Bromination at C-8 of the NADP+ adenine ring, followed by reaction with the disodium salt of 3-mercaptopropionic acid, gave 8-(2-carboxyethylthio)-NADP+. Carbodiimide coupling of the 3 carboxylic NADP+ derivatives to polyethyleneimine afforded the corresponding macromolecular NADP+ analogues. The carboxylic and the polyethyleneimine derivatives synthesized were coenzymically active with yeast glucose-6-phosphate dehydrogenase, liver glutamate dehydrogenase and yeast aldehyde dehydrogenase. The degree of efficiency relative to NADP+ with the 3 enzymes ranged from 17-100% for the carboxylic derivatives and from 1-36% for the polyethyleneimine analogues. On comparing the efficiencies with the 3 enzymes of the N-1 derivatives to the one of the corresponding N6 and C-8 analogues, the order of activity was N-1 > N6 > C-8, except in the case of the carboxylic compounds with glutamate dehydrogenase, where this order was inverted. None of these modified cofactors were active with pig heart isocitrate dehydrogenase.