Studies on the interaction of magnesium, calcium and strontium ions with native and chemically modified human serum albumin

Abstract

Interactions of Ca2+, Mg2+ and Sr2+ ions with native and chemically modified human albumin are similar. The relative binding affinity to native albumin is: Ca2+ > Mg2+ > Sr2+ ions, and to the modified albumin Ca2+> Mg2+, Sr2+ ions. The binding to native, esterified and acetylated albumins is governed mainly by electrostatic attraction to non-specific sites, although with native albumin specific site binding has also been found. Binding to phosphorylated and bromoacetylated albumins occurs through specific sites. In the presence of citrate ions, Ca2+ ions are bound to native albumin at pH values below 5. 2 as a negatively charged calcium citrate complex and at pH values above 5 2 as the free ion.