DETERMINATION OF THE RATES OF FORMATION AND HYDROLYSIS OF THE SCHIFF-BASES FORMED BY PYRIDOXAL AND POLY-L-LYSINE

Abstract

The rate constants of formation (k1ex) and hydrolysis (k2) of the Schiff bases of pyridoxal (PL) with poly-L-lysine were determined as a function of pH at a temperature of 25-degrees-C and an ionic strength I=0.1 M. The k1ex and k(pH) values obtained at every pH assayed were all smaller than those reported for the formation of Schiff bases between pyridoxal 5'-phosphate (PLP) and poly-L-lysine as a result of the occurrence of PL as a hemiacetal. The Schiff bases of PL with poly-L-lysine are more readily hydrolysed than those of PLP with the same polymer. The carbon-nitrogen double bond of the Schiff bases studied in this work lies in a hydrophobic environment similar to that provided by ethyl alcohol in terms of polarity.