Binding of bilirubin and long-chain fatty acids to human serum albumin with general remarks on displacement of firmly bound ligands.
Binding of bilirubin to human serum albumin was studied by estimation of the free bilirubin concentration from the rate of oxidation with hydrogen peroxide and peroxidase, and by spectrophotometry: nI = 1, kI = 7 x 10(7) l/mol; nII = 1, kII = 5 x 10)5) l/mol, at pH 7.4, 37 degrees C, ionic strength 0.1. Palmitate or oleate in excess of 4 mol per mol albumin, influences the high-affinity binding of bilirubin as described by an empirical equation. Theoretical consideration of competitive displacement of a biologically active substance, firmly bound in an inactive state to a macromolecular carrier, demonstrates that significant displacement may occur on addition of another ligand with a lower binding constant. Displacement of bilirubin from its high-infinity site by fatty acids and drugs is thermodynamically feasible and probably clinically important.
D001663:Bilirubin / Q000378:metabolism*; D001665:Binding Sites; D001667:Binding, Competitive; D005227:Fatty Acids / Q000378:metabolism*; D006735:Horseradish Peroxidase; D006801:Humans; D006861:Hydrogen Peroxide; D007231:Infant, Newborn; D007647:Kernicterus / Q000097:blood; D008954:Models, Biological; D009829:Oleic Acids / Q000378:metabolism; D010168:Palmitates / Q000378:metabolism; D012709:Serum Albumin / Q000378:metabolism*; D013053:Spectrophotometry
D005227:Fatty Acids; D009829:Oleic Acids; D010168:Palmitates; D012709:Serum Albumin; D006861:Hydrogen Peroxide; D006735:Horseradish Peroxidase; D001663:Bilirubin