SPECTRAL PROPERTIES OF PYRIDOXAL 5'-PHOSPHATE ALDIMINES WITH SOME AROMATIC-AMINO-ACIDS AND THEIR ANALOGS - TAUTOMERIC AND ISOMERIC EQUILIBRIA

Spectral properties of the ionic forms of pyridoxal 5'-phosphate aldim ines with phenylalanine, tyrosine, phosphonic, and phosphonous phenyla lanine analogues and pH-dependent transitions between these forms were studied. The tautomeric and isomeric composition of these equilibrium mixtures was determined. The spectral properties of these compounds w ere shown to be very close to those of the aldimines of pyridoxal 5'-p hosphate with the other amino acids studied previously. At the same ti me, significant differences in the content of the tautomeric and confo rmational forms were observed. The substitution of the phosphonic or p hosphonous group for the carboxyl group also influenced the content of various tautomeric forms, planar and rotational conformers.