title: Impurity in buffer substances mimics the effects of ATP on soluble 5'-nucleotidase.
abstract: An impurity, probably an anion, present in some batches of the buffer substances 4-(2-hydroxyethyl) piperazine-1-ethanesulfonic acid (HEPES), 2-morpholinoethane sulfonic acid (Mes) and piperazine-1,4-bis(2-ethane sulfonic acid (Pipes), activates the soluble 5'-nucleotidase from rat kidney. The affinity of the enzyme for 5'-IMP and the Vmax were both increased by the unidentified activator. ATP and 2,3-diphosphoglycerate, known activators of the soluble 5'-nucleotidase, had no effect if the incubation media were buffered with batches containing high concentrations of the activating impurity. These results suggest that the impurity interacts with the soluble 5'-nucleotidase at the same site as ATP and 2,3-diphosphoglycerate, however with a much higher affinity than these two compounds. It is possible that the same impurity might interfere with other proteins for which ATP is a substrate or a ligand.
authors.affiliation: Department Forschung, Medizinische Universitäts-Poliklinik, Kantonspital Basel, Switzerland.
authors.forename: M
authors.initials: M
authors.lastname: Le Hir
mesh_terms: D015720:5'-Nucleotidase / Q000187:drug effects*; D000255:Adenosine Triphosphate / Q000494:pharmacology*; D000476:Alkanesulfonates / Q000737:chemistry / Q000494:pharmacology*; D017738:Alkanesulfonic Acids; D002021:Buffers; D004789:Enzyme Activation / Q000187:drug effects; D006531:HEPES / Q000737:chemistry / Q000494:pharmacology*; D007700:Kinetics; D009025:Morpholines / Q000737:chemistry / Q000494:pharmacology*; D010879:Piperazines / Q000737:chemistry / Q000494:pharmacology*; D012995:Solubility
chemical_list: D000476:Alkanesulfonates; D017738:Alkanesulfonic Acids; D002021:Buffers; D009025:Morpholines; D010879:Piperazines; C004550:2-(N-morpholino)ethanesulfonic acid; D000255:Adenosine Triphosphate; D015720:5'-Nucleotidase; C008916:piperazine-N,N'-bis(2-ethanesulfonic acid); D006531:HEPES