Synthesis and Characterization of 8-(6-Aminohexyl)-amino-NADH

8-(6-aminohexyl)-amino-NADH was successfully prepared by modifying NADH with 1,6-hexanediamine at the C8 position of adenine moiety. After 3-step synthesizing process, the product was purified on DEAE-Sepharose column with the final yield up to 60%. The stability of NH2(CH2)6NH-NADH in acid or neutral environment was studied and compared with the native NADH. The results showed that the modified NADH was more stable than the native one, particularly in the citric acid-sodium citrate buffer (pH 6.5) and phosphate buffer (pH 8.0), the half life of modified NADH increased 11.0 folds and 5.0 folds, respectively. Catalytic activity of the modified NADH was evaluated with lactate dehydrogenase (LDH) and glutamate dehydrogenase (GDH) systems. For LDH and GDH, the activity for NH2(CH2)6NH-NADH was 3.0～3.8 or 1.3～1.4 times higher than that of native NADH, respectively.