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-acetate buffer (3.9–5.5) at an ionic strength of 0.1 M and a temperature of 25°C. The results were consistent with the rapid formation of an ionized carbinolamine, T+, followed by deprotonation, in the rate-determining step, to a neutral carbinolamine, T°. Subsequent dehydration of T° in a rapid step yields the final Schiff base. The formation of T+ is a concerted process subject to specific acid catalysis. © 1995 John Wiley & Sons, Inc.