title: The interaction of proteins with hydroxyapatite. I. Role of protein charge and structure.
abstract: The criteria for elution of proteins from hydroxyapatite columns were examined as a function of (1) protein isoelectric point (22 proteins with isoelectric points between 3.5 and 11.0); (2) ionic nature of eluant (Na salts of PO4, F-, Cl-, SCN-, ClO-4, and CaCl2); and (3) structural differences between related proteins. It was found that proteins can be classified into three groups: (1) basic proteins, which elute at similar, moderate molarities of PO4, F-, Cl-, SCN-, and ClO-4, and low (less than 0.003 M) Ca2+; (2) acidic proteins which elute at about equal moderate molarities of PO4 and F-, but do not elute with Ca2+ and usually not with Cl-; (3) neutral proteins, which elute with PO4, F-, and Cl-, but show a strong anion specificity, and do not elute with Ca2+ or SCN-. Furthermore, individual specific polar groups are not in general crucial to binding or desorption, and variations in structure, other than major loosening, do not influence strongly the pattern of protein-hydroxyapatite interaction.
mesh_terms: D055598:Chemical Phenomena; D002621:Chemistry; D002845:Chromatography / Q000379:methods*; D002918:Chymotrypsin / Q000302:isolation & purification; D002919:Chymotrypsinogen / Q000302:isolation & purification; D006882:Hydroxyapatites; D007526:Isoelectric Point; D007782:Lactoglobulins / Q000302:isolation & purification; D011506:Proteins / Q000302:isolation & purification*; D013329:Structure-Activity Relationship
chemical_list: D006882:Hydroxyapatites; D007782:Lactoglobulins; D011506:Proteins; D002919:Chymotrypsinogen; D002918:Chymotrypsin