Binding of selenoprotein P to heparin: characterization with surface plasmon resonance.
The binding of selenoprotein P to glycosaminoglycans using heparin as a model compound was studied by surface plasmon resonance. It was found that heparin contains two binding sites for selenoprotein P, a high-affinity, low-capacity site (Kd approximately 1 nM) and a low-affinity, high-capacity site (Kd approximately 140 nM). Binding at both sites is sensitive to pH and ionic strength, and the high-affinity site is abolished by histidine carbethoxylation with diethylpyrocarbonate. The pH and salt dependence of binding suggests electrostatic interactions with heparin. The concentrations of selenoprotein P in plasma (approximately 50 nM) are sufficiently high to facilitate binding of selenoprotein P to proteoglycans on the vascular endothelium, and this may contribute to the formation of a protective barrier against oxidants such as peroxynitrite or hydroperoxides.
Arteel
G E
GE
Institut für Physiologische Chemie I, Neurologische Klinik, und Biologisch-Medizinisches Forschungszentrum, Heinrich-Heine-Universität, Düsseldorf, Germany.
Franken
S
S
Kappler
J
J
Sies
H
H
D006493:Heparin / Q000378:metabolism*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D009994:Osmolar Concentration; D011506:Proteins / Q000378:metabolism*; D051149:Selenoprotein P; D051140:Selenoproteins; D020349:Surface Plasmon Resonance
D011506:Proteins; D051149:Selenoprotein P; D051140:Selenoproteins; D006493:Heparin