Interaction between hydroxyapatite and proteins by liquid chromatography using simulated body fluids as eluents

Hydroxyapatite (HAp) column chromatography for proteins using simulated body fluids (SBFs) as eluents was investigated in order to mimic the flow environment of human body fluid on the HAp surface in vivo. Acidic plasma proteins such as albumin, gamma-globulin, and fibrinogen having carboxyl groups with a negative charge were suggested to adsorb at positively charged sites (Ca sites) on the HAp surface. These acidic plasma proteins were not even eluted at higher inorganic ion molarities of human body fluid. Whereas basic proteins such as papin, cytochrome c, and lysozyme were easily eluted at lower inorganic ion molarities of human body fluid due to existing Na(+), Ca(2 +), Mg(2 +) and (CH(2)OH)(3)CNH(4)(+) ions in the eluents. The elution behavior of proteins using SBF in the presence or absence of glucose did not change. From these considerations, bone matrix proteins as acidic and neutral proteins would be considered an advantageous condition in order to adsorb on HAp in vivo.