title: Suramin--a powerful inhibitor of neural ecto-diadenosine polyphosphate hydrolase.
abstract: The neural ecto-diadenosine polyphosphate hydrolase (ecto-ApnAase) from plasma membranes of Torpedo synaptic terminals is inhibited by suramin. This study was carried out by discontinuous h.p.l.c. and continuous fluorometric methods. The concentration-dependence studies showed a non-competitive mechanism for suramin in the Dixon plot, with a Ki value of 1.79 +/- 0.03 microM with respect to epsilon-(Ap3A) as the substrate and 1.69 +/- 0.05 microM and 1.86 +/- 0.06 microM for epsilon-(Ap4A) and epsilon-(Ap5A) respectively. These results indicate that suramin could be a base compound inhibiting ecto-ApnAase and providing an alternative way of studying the pharmacology of diadenosine polyphosphate receptors.
authors.affiliation: Departamento de Bioquímica, Facultad de Veterinaria, Universidad Complutense de Madrid, Spain.
authors.forename: J
authors.initials: J
authors.lastname: Mateo
authors.forename: P
authors.initials: P
authors.lastname: Rotllán
authors.forename: M T
authors.initials: MT
authors.lastname: Miras-Portugal
mesh_terms: D017766:Acid Anhydride Hydrolases / Q000032:analysis* / Q000037:antagonists & inhibitors* / Q000378:metabolism; D000818:Animals; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D004305:Dose-Response Relationship, Drug; D004557:Electric Organ / Q000187:drug effects / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005470:Fluorometry; D007700:Kinetics; D013498:Suramin / Q000494:pharmacology*; D013569:Synapses / Q000187:drug effects / Q000201:enzymology*; D014101:Torpedo / Q000378:metabolism
chemical_list: D004791:Enzyme Inhibitors; D013498:Suramin; D017766:Acid Anhydride Hydrolases; C075829:diadenosine polyphosphate hydrolase