Palladium(II) Complexes Containing Mixed Nitrogen-Sulphur Donor Ligands: Interaction of [Pd(Methionine Methyl Ester)(H₂O)₂]²⁺ with Biorelevant Ligands

Table 2

Formation constants for complexes of [Pd(MME)(H₂O)₂]²⁺ with peptides at 25°C and 0.1 M ionic strength.

System	M	L	H^a
Glycinamide	0	1	1	7.88 (0.02)	7.88
	1	1	0	7.25 (0.05)
	1	1	−1	3.96 (0.01)	3.29
Glycylglycine	0	1	1	7.94 (0.01)	7.94
	0	1	2	10.80 (0.01)	2.86
	1	1	0	8.55 (0.04)
	1	1	−1	3.17 (0.06)	5.38
Asparagine	0	1	1	8.56 (0.01)	8.56
	1	1	0	9.11 (0.03)
	1	1	−1	1.63 (0.04)	7.48
Glutamine	0	1	1	9.50 (0.01)	9.50
	1	1	0	9.78 (0.06)
	1	1	−1	0.93 (0.01)	8.85

^aM, L, and H are the stoichiometric coefficients corresponding to Pd(MME), peptides, and H⁺, respectively; the coefficient −1 refers to a proton loss; ^b of Pd(MME)-peptide complexes, standard deviations are given in parentheses and sum of square of residuals is less than ; ^cthe p of the peptides or of coordinated peptides.