Nucleoside polyphosphopyridoxal

Fig. 4. Nucleoside polyphosphopyridoxals. (a) Adenosine diphosphopyridoxal (b) uridine diphosphopyridoxal and (c) guanosine diphosphopyridoxal.

As a class of affinity labels, the nucleoside polyphosphopyridoxals exhibit many of the favorable features without many of the drawbacks of the periodate-oxidized nucleotides. The nucleoside polyphosphopyridoxals are structurally close to the natural coenzymes, are water soluble and negatively charged at neutral pH, and exhibit high affinity for the enzymes with which they have been tested. Their targets have thus far been limited to lysine residues, but they react to form Schiff bases which can be stabilized by reduction with NaBH4. Once reduced, the products are stable throughout the peptide purification procedures, and the sequences of the modified peptides can readily be determined. 

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