Coordination Tendency of Some Biologically Important Zwitterionic Buffers toward Metal Ion Nucleotide Complexes at Different Temperatures

The formation of binary and ternary complexes of Cu(II), Co(II), Mn(II), Zn(II), Ca(II), Mg(II), and Pd(II) with 4-morpholinoethane sulfonic acid (MES), 2-(cyclohexylamino)ethane sulfonic acid (CHES), and 3-[(N-tris)-(hydroxymethyl)methyl (amino)]-2-hydroxypropanesulfonic acid (TAPSO) as zwitterionic buffers and guanosine 5'-monophosphate (5'-GMP), inosine 5'-monophosphate (5'-IMP), and uridine 5'-mono-phosphate (5'-UMP) has been studied potentiometrically in the temperature range (288.15 to 318.15) K and at ionic strength I = 0.1 mol.dm(-3) (KNO3). Initial estimates of the formation constants of the resulting species and the dissociation constants of the studied ligands have been refined with the SUPERQUAD computer program. The experimental conditions were selected such that self-association of the nucleotides and their complexes was negligibly small; that is, the monomeric and protonated complexes were studied.