Characterization of Cattle Bone-Originated Apatite Powders by the Adsorption Behavior of Different Proteins

Cattle bone-originate apatite (r-HAp) prepared by a dissolution-precipitation method had a Ca^<2＋>-deficient structure containing small amounts of Mg^<2＋> and Na^＋ions. The r-Hap powder, which consisted of aggregates of microcrystals 20〜30 nm in size，was found to be more advantageous as an adsorbent than a hydroxyapatite powder synthehesized from reagents, because of its large specific surface area 100m^2 ･g^<-1>. For the r-Hap powder, the adsorption for each of the five different proteins ? bovine serum albumin (BSA)，myoglobine from horse skeletal muscle(MOG), ribonuclease A from bovine pancreas (RBN), lysozyme from chicken egg white (LSZ)，and cytochrome-c from horse heart (CTC)−obeyed the Langmuir equation. The saturated amounts of LSZ and CTC (isoelectric points (E-o)＜7.0) adsorbed were 2〜15 times larger than those of BSA and MOG (E-o＜7.0) adsorbed. The basic and acidic proteins can be selectively adsorbed on the P-and C-sites of the hydroxyapatite surface, repectively , suggesting that on the r-HAp surface，the number of P-sites would be greater than the number of C-sites