Oxidation and cleavage of 3-aminopyridine adenine dinucleotide phosphate with periodate

Treatment of 3-aminopyridine adenine dinucleotide phosphate with sodium periodate in the neutral pH resulted in oxidation of the ribose linked to 3-aminopyridine and cleavage of the dinucleotide into adenosine and 3-aminopyridine-containing moieties. Separation of these moieties was afforded by thin-layer chromatography, high-performance liquid chromatography, and fast, protein liquid chromatography. From fast atom bombardment mass spectra and nuclear magnetic resonance spectra, the adnosine-containing moiety was identified as 2′-phosphoadenosine 5′-phosphate while the aminopyridine moiety was present in a mixture of the hydrated 3-aminopyridine mononucleotide/nucleoside dialdehyde. Separation of the completely oxidized product by Pharmacia fast protein liquid chromatography gave three major peaks corresponding to 2′-phosphoadenosine 5′ phosphate, 2′-phosphoadenosine 5′-diphosphate and oxidezed 3-aminopyridine nucleoside, with minor amount of oxidized 3-aminopyridine mononucleotide. Thus the oxidized 3-aminopyridine adenine dinucleotide phosphate was shown to cleave bu two pathways: it may either undergo β-elimination to give 2′-phosphoadenosine 5′-diphosphate and oxidized 3-aminopyridine nucleoside; or the phosphodiester linkage may be hydrolyzed to give 2′-phosphoadenosine 5′-phosphate and oxidized 3-aminopyridine mononucleotide. The latter compound may futher undergo β-elimination eventually give oxidized 3-aminopyridine nucleoside. Hydrolysis could be prevented by storing the sample as lyophilized powder, while β-elimination was diminished by lowering the storage temperature. We found that the lyophilixzed powder of oxidized 3-aminopyridine adenine dinucleotide phosphate can be stored at 50°C for several months with minimum decomposition.