title: Role of the membrane concanavalin A binding site in platelet-fibrin interactions.
abstract: Concanavalin A was employed to study the role of platelet membrane glycoproteins in platelet-fibrin interactions during clot formation. A rheological technique was used to study the interactions, measuring the clot rigidity and platelet contractile force simultaneously during the formation of network structure. Concanavalin A lowered the clot rigidity and contractile force of a platelet-rich plasma clot by a small extent. Plasma glycoproteins probably compete with platelet membranes for concanavalin A binding in platelet-rich plasma. Both native concanavalin A (tetrameric) and succinyl concanavalin A (dimeric) lowered the clot rigidity and contractile force of a washed platelet-fibrin clot dramatically, almost down to those values found for fibrin clots. Inhibition studies with alpha-methyl-D-mannoside indicated that the concanavalin A effects were specific for the concanavalin A binding capacity to platelets. The effects of native concanavalin A on platelet-fibrin clots were only partially reversible, while the succinyl concanavalin A effects were completely reversible. The observed concanavalin A effects are probably mainly due to concanavalin A binding to platelet membrane glycoproteins. The concanavalin A binding site appears to play an important role in the fibrin binding to platelets.
mesh_terms: D001665:Binding Sites; D001791:Blood Platelet Disorders / Q000378:metabolism; D001792:Blood Platelets / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D003208:Concanavalin A / Q000031:analogs & derivatives / Q000494:pharmacology; D005337:Fibrin / Q000378:metabolism*; D005340:Fibrinogen / Q000378:metabolism; D006801:Humans; D007700:Kinetics; D046911:Macromolecular Substances; D011952:Receptors, Concanavalin A / Q000378:metabolism*; D012212:Rheology
chemical_list: D046911:Macromolecular Substances; D011952:Receptors, Concanavalin A; D003208:Concanavalin A; C019558:succinylconcanavalin A; D005337:Fibrin; D005340:Fibrinogen