title: Heparin and concanavalin A interaction as a model for studying the mechanism of the anticoagulant activity.
abstract: A systematic study of the role of the Ca2+ and Mn2+ ions on the interaction between heparin and Concanavalin A was carried out. The protein was demetallized, and complex formation was followed by a light scattering assay. In the absence of ions no visible interaction was detected. Maximum activity was obtained when Mn2+ ions were added. A similar effect was observed when Ca2+ ions alone were used. Kinetics of the interaction in the presence of optimal Mn2+ and(or) Ca2+ concentrations confirmed the role of Ca2+ in accelerating a conformational change leading to a functional protein. A peculiar effect of activation-inhibition depending on ion concentration was also exhibited by Ca2+. These results confirm that Ca2+ and Mn2+ can occupy both sites on Concanavalin A and activate the protein for binding heparin. They point also to a crucial role of Ca2+ in the binding capacity of the active heparin fraction.
authors.affiliation: Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Buenos Aires, Argentina.
authors.forename: J C
authors.initials: JC
authors.lastname: Monge
authors.forename: E F
authors.initials: EF
authors.lastname: Recondo
authors.forename: M E
authors.initials: ME
authors.lastname: Fernández de Recondo
mesh_terms: D001667:Binding, Competitive; D001777:Blood Coagulation / Q000187:drug effects*; D002118:Calcium / Q000494:pharmacology; D003208:Concanavalin A / Q000494:pharmacology*; D004347:Drug Interactions; D006493:Heparin / Q000494:pharmacology*; D007700:Kinetics; D008027:Light; D008345:Manganese / Q000494:pharmacology; D008954:Models, Biological; D011487:Protein Conformation; D012542:Scattering, Radiation; D013053:Spectrophotometry
chemical_list: D003208:Concanavalin A; D008345:Manganese; D006493:Heparin; D002118:Calcium