Complexes of vitamin B-6. 23. Interaction of some tertiary ligating amino acids with the binary complexes of Ni(II) or Cu(II) and pyridoxamine

Binary and ternary complexes involved in the systems pyridoxamine (PM), glu tamic acid (Glu), or aspartic acid (Asp) plus Ni(II) or Cu(II) were studied in solution at 0.15 M ionic strength and 25 degrees C by pH-metric, absorp iometric, and polarographic techniques. The differential pulse polarographi c technique was used to study Be reduction properties of these complexes. E PR was used to confirm the presence of binary and ternary complex species i n the Cu(II) systems. The stoichiometry and formation constants of the bina ry and ternary complex species were determined by the SUPERQUAD program. Te rnary species of the types 1:1:1:r and 1:2:1:r (PM/Glu or Asp/M/H) were fou nd to exist in the pH range similar to 3 to similar to 10.