Stabilitätskonstanten einiger Co^2⊕-, Ni^2⊕- und Ag^⊕-Nucleotide / Stability Constants of some Co^2⊕-, Ni^2⊕-, and Ag^⊕-nucleotides

Abstract

The stability constants of some Co 2⊕ , Ni 2⊕ and Ag ⊕ nucleotides have been measured employing difference spectrophotometry. AMP, ADP, ATP, salmon sperm DNA and nuclear RNA from rat liver served as ligands. In all studies the numerical values of log β ranged in the same order of magnitude, generally about 4.3 ± 0.4. According to neglecting differences in the absorbancy at 260 nm the theory was confirmed that Co 2⊕ and Ni 2⊕ nucleotides may be assigned to metal chain complexes i. e. the metals are preferentially coordinated with the phosphate chain of the nucleotides. This is in contrast to profound changes of E 260 if Ag ⊕ ions were used. These complexes arc to be considered as rather pure metal-base complexes where the metal ion is strongly suggested to be bound to the nitrogen atoms of the heterocyclic base pairs.