title: Synergistic effects of lectins in the interaction of thrombin with human platelets.
abstract: Several lectins have been studied for their effects on the interaction of thrombin with human platelets. Wheat germ agglutinin, concanavalin A and Ricinus communis lectin increased the number of high affinity sites for diisopropylphosphothrombin on washed platelets from 3000 to about 12 000 but the binding affinities were unchanged (Kd approx 4 nM). Two other lectins, Lens culinaris and Bandieria simplicifolia, were without effect. (2) Using formalinized platelets to avoid possible complications of the platelet release reaction, wheat germ agglutinin showed a marked increase (5-fold) in the binding of active thrombin, peanut agglutinin had no effect while Ricinus communis and :Bandieria simplicifolia showed marginal increases (2-fold). Thrombin binding was decreased to about one quarter with Lens culinaris, Phaseolus vulgaris and concanavalin A. (3) Wheat germ agglutinin caused a synergistic increase of platelet aggregation at low concentrations of thrombin (12.5 mU/ml) and ADP (1 microM), both in the absence and presence of added fibrinogen, but had no effect on ristocetin-induced aggregation.
mesh_terms: D001665:Binding Sites; D001792:Blood Platelets / Q000378:metabolism; D005340:Fibrinogen; D006801:Humans; D037102:Lectins / Q000494:pharmacology*; D010974:Platelet Aggregation / Q000187:drug effects*; D013917:Thrombin / Q000378:metabolism*; D014909:Wheat Germ Agglutinins
chemical_list: D037102:Lectins; D014909:Wheat Germ Agglutinins; D005340:Fibrinogen; D013917:Thrombin