Computer simulation of metal-ion equilibria in biofluids. Part 2. Formation constants for zinc(II)–citrate–cysteinate binary and ternary complexes and improved models of low-molecular-weight zinc species in blood plasma

Abstract

Equilibrium-based computer models of biofluids can be improved by establishing the exact values for the formation constants of complexes present. This work reports the compositions of the complex species and log β values for the zinc citrate, zinc cysteinate, and zinc citrate cysteinate systems at 37 °C and l= 0.15 mol dm^–3 Na[ClO₄]. The most important low-molecular-weight zinc complexes in blood plasma are found to be [Zn(CysO)₂]^2– and [Zn(CysO)(HisO)]^–(CysO = cysteinate, HisO = histidinate).