Chemical transformations of pyridoxal and pyridoxal 5′-phosphate condensation products with amino acids
作者:F. V. Pishchugin、I. T. Tuleberdiev
DOI:10.1134/s1070363208060212
日期:2008.6
The mechanism ot'cheinical transformations ofpyridoxal and pyridoxal 5'-phosphate condensation products with amino acids is studitd by kinetic measurements. The Schiff bases are shown to be fairly stable in neutral media. In acid media, the Schiff bases are hydrolyzed into the initial components. In alkaline inedia, cleavage of a-hydrogen from tht amino acid fragment and structural rearran-ement into the qUinoid forin followed by hydrolysis of' the]alter with elimination of pyridoxamine and keto acid take place. The rate constants of the chemical transfori nations of the Schiff bases are found to depend on the pH of the medium. It is shown for the first time that the Dhosphate group in the pyridoxal 5'-phosphate fragment catalyzes the a-hydL_ C rooen cleavaoe and strongly accelerates alkaline decomposition of the Schiff bases.