Kinetic study of the reaction of pyridoxal 5 '-phosphate with hydrazino compounds of pharmacological activity
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Date
1998
Journal Title
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Volume Title
Publisher
WILEY-V C H VERLAG GMBH
Abstract
The kinetics of the reaction between pyridoxal 5'-phosphate (PLP) with carbidopa, hydralazine, and isoniazid, in aqueous solution at variable pH and constant ionic strength of 0.1M was studied spectrophotometrically. The rate constants of formation and hydrolysis of the resulting Schiff base, and its stability were determined in a wide rang of pH. A comparison is made of the formation rate constants with those of PLP with hydrazine. The reactivity shows the sequence isoniazid > hydrazine > carbidopa > hydralazine in the whole range of pH studied. The Schiff bases studied are more stable than those formed by PLP and hexylamine and as stable as those described for the reactions of PLP with poly(L-lysine) or copolypeptides containing L-lysine.
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Keywords
WATER-DIOXANE MIXTURES, SCHIFF-BASE FORMATION, NORMAL-HEXYLAMINE, L-LYSINE, THERMODYNAMIC PARAMETERS, NONAQUEOUS MEDIA, AMINO-ACIDS, 5'-DEOXYPYRIDOXAL, HYDROLYSIS, STABILITY