Binding characteristics of human serum amyloid P component.
Serum amyloid P component (SAP), a normal human plasma glycoprotein, was found in a solid phase ELISA to have Ca2+-dependent binding for keyhole limpet haemocyanin (KLH), pectic acid, trinitrophenylated (TNP) macromolecules, and plastic surfaces. The binding to TNP-KLH was used to develop a sensitive ELISA. The binding of SAP to the ligands mentioned was inhibited by EDTA, KLH, pectic acid, TNP-conjugated macromolecules (bovine serum albumin, polyacrylhydrazide), and p-nitrophenylarsonic acid. Underivatized and DNP-conjugated macromolecules did not inhibit the SAP binding; arsenilic acid, picric acid, and dinitrophenyl were weak inhibitors. SAP bound to TNP-agarose was eluated by either EDTA or p-nitrophenylarsonic acid. Thus, a unique region of SAP is responsible for the polyspecific binding. We suggest that the polyspecific binding of SAP takes place through a Ca2+ bridge: half of the metal coordination sphere is occupied by SAP, with the other half available to interact with metal ligand.
D002097:C-Reactive Protein / Q000378:metabolism; D002118:Calcium / Q000494:pharmacology; D002850:Chromatography, Gel; D004492:Edetic Acid / Q000494:pharmacology; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D006433:Hemocyanins / Q000378:metabolism; D006801:Humans; D010368:Pectins / Q000378:metabolism; D010969:Plastics / Q000378:metabolism; D011485:Protein Binding; D012710:Serum Albumin, Bovine / Q000378:metabolism; D000683:Serum Amyloid P-Component / Q000302:isolation & purification / Q000378:metabolism*; D013499:Surface Properties; D014301:Trinitrobenzenes / Q000378:metabolism
D010969:Plastics; D000683:Serum Amyloid P-Component; D014301:Trinitrobenzenes; D012710:Serum Albumin, Bovine; D010368:Pectins; D002097:C-Reactive Protein; D006433:Hemocyanins; D004492:Edetic Acid; C032808:keyhole-limpet hemocyanin; D002118:Calcium; C003181:polygalacturonic acid