Estimation of the Effectiveness of the Phosphate Group in Binary Phosphoserine/Biogenic Amine Systems in Aqueous Solution

摘要

Adduct formation in the binary systems of O-phospho-L-serine with biogenic amines (putrescine, spermidine or spermine) has been investigated. The overall stability constants of the adducts and the equilibrium constants of their formation have been determined using computer analysis of potentiometric data. Ion-ion interactions have been established to occur in the identified molecular complexes. The potential reaction centers are phosphate, carboxylate and amine groups from phosphorylated serine as well as the -NH (3) (+) and -NH (2) (+) - groups from polyamine. The pH range of adduct formation is found to coincide with that in which the polyamine is protonated (positive reaction center) and the phosphoserine is partly or totally deprotonated (negative reaction center). The stability of the molecular complexes formed in the studied systems depends on the acid-base character of the substrates and on the structure of the reacting molecules. Sites of interactions in the bioligands have been deduced on the basis of the results of the equilibrium study and analysis of the changes in the positions of signals in the C-13 and P-31 NMR spectra.