The use of PEG-NADH/Na2Co3 Aqueous Two-Phase Systems for the Large-Scale Preparation of Technical Grade PEG-(Mr 20,000)-N6-(2-Aminoethyl)-NADH
A procedure for the preparation of technical grade poly(ethylene glycol) (PEG) (Mr 20,000)-N6-(2-aminoethyl)-NADH was developed. Using the reaction mixture after the alkylation of NAD by ethyleneimine, containing 25% unreacted NAD, 67% (N(1)-(2-aminoethyl)-NAD, and 8% (N(1)-NAD by-products, technical grade PEG (Mr 20,000)-N(1)-(2-aminoethyl)-NAD was synthesised by the carbodiimide coupling method. After chemical reduction to PEG (Mr 20,000)-N(1)-(2-aminoethyl)-NADH and Dimroth rearrangement, technical grade PEG (Mr20,000)-N6-(2-aminoethyl)-NADH was obtained with an overall yield of 33.5% [Table 1, Fig. 1]. By insertion of a cation-exchange purification step in batch mode after the coupling step and partitioning in PEG-NADH/Na2CO3 aqueous two-phase systems before and after the Dimroth-rearrangement step >98% of the uncoupled NAD(H), N(1)-(2-aminoethyl)-NAD(H), and alkylated NAD(H) by-products could be removed. Because large volumes may be handled easily in these operations, the procedure developed for the preparation of technical grade PEG(Mr 20,000)-N6-(2-aminoethyl)-NADH can now be adapted to large-scale synthesis .
KeywordsEthylene Glycol Aqueous Phase Large Volume Reaction Pathway Chemical Reduction
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- 1.A.F. Bückmann, Biotechnol. Appl. Biochem. 9:258 (1987)Google Scholar