DETERMINATION OF THE RATE OF FORMATION OF THE SCHIFF-BASES OF PYRIDOXAL 5'-PHOSPHATE WITH POLYALLYLAMINE

The formation constants of the Schiff bases of pyridoxal 5'-phosphate with polyallylamine were determined over the pH range of the acetic-ac etate buffer (3.9-5.5) at an ionic strength of 0.1 M and a temperature of 25 degrees C. The results were consistent with the rapid formation of an ionized carbinolamine, T+, followed by deprotonation, in the ra te-determining step, to a neutral carbinolamine, T degrees. Subsequent dehydration of T degrees in a rapid step yields the final Schiff base . The formation of T+ is a concerted process subject to specific acid catalysis. (C) 1995 John Wiley & Sons, Inc.