Mag. Delvado et al., DETERMINATION OF THE RATES OF FORMATION AND HYDROLYSIS OF THE SCHIFF-BASES FORMED BY 5'-DEOXYPYRIDOXAL AND POLY-L-LYSINE, Journal of molecular catalysis. A, Chemical, 118(1), 1997, pp. 21-26
The kinetics of the reaction between 5'-deoxypyridoxal (DPL) and poly-
L-lysine in aqueous solutions at a variable pH and a constant ionic st
rength of 0.1 M was studied spectrophotometrically. The rate constants
of formation and hydrolysis of the resulting Schiff base and its stab
ility constant at a variable pH were also determined. A comparison of
the formation rate constant for the Schiff base with those for the mod
els of pyridoxal 5'-phosphate (PLP) with poly-L-lysine and DPL with n-
hexylamine revealed the effect of both the phosphate group of PLP and
of the polypeptide chain on intramolecular catalysis in the dehydratio
n of the intermediate carbinolamine formed. The effects of the polypep
tide and the phosphate group on the hydrolysis of the Schiff base and
hence on the base stability are also demonstrated.