Binding of serum amyloid P component to heparin in human serum.
It has been proposed that the function of serum amyloid P component (SAP) may closely relate with its binding to polysaccharides, especially glycosaminoglycans. We employed a quantitative immunoelectrophoresis (QIE) method and a native polyacrylamide gel electrophoresis (PAGE) method to characterize the SAP-heparin binding in soluble state. The SAP-heparin binding showed positive cooperativity. The apparent numbers of heparin molecules bound to SAP varied with the calcium concentration with a ratio of 1:1 (SAP/heparin), a Kd of 2.06 x 10(-7) M at 0.1 mM CaCl2 and a ratio of 1:1.6 (SAP/heparin), a Kd of 3.91 x 10(-7) M at 2 mM CaCl2, when estimated by the QIE method. No binding between SAP and heparin was observed in the absence of calcium. Magnesium and barium failed to induce the formation of SAP-heparin complex. Furthermore, they showed inhibitory effects on the calcium-mediated complex formation. We propose that heparin might be a regulator to modulate the anticoagulant activity of SAP and a useful drug to prevent SAP deposition on amyloid deposits.
Li
X A
XA
Department of Etiology/Pathophysiology, National Cardiovascular Center Research Institute, Osaka, Japan.
Hatanaka
K
K
Guo
L
L
Kitamura
Y
Y
Yamamoto
A
A
D001464:Barium / Q000494:pharmacology; D002118:Calcium / Q000494:pharmacology; D006493:Heparin / Q000097:blood / Q000378:metabolism*; D006801:Humans; D008274:Magnesium / Q000494:pharmacology; D000683:Serum Amyloid P-Component / Q000378:metabolism*
D000683:Serum Amyloid P-Component; D001464:Barium; D006493:Heparin; D008274:Magnesium; D002118:Calcium