Nucleotide metabolizing ecto-enzymes in Walker 256 tumor cells: molecular identification, kinetic characterization and biochemical properties.

摘要: Abstract In this study we describe the molecular identification, kinetic characterization and biochemical properties of an E-NTPDase 5′-nucleotidase in Walker 256 cells. For ATP, ADP AMP hydrolysis there were optimum pH range 6.5–8.0, absolute requirement for divalent cations (Mg 2+  > Ca ). A significant inhibition ATP was observed presence high concentrations sodium azide 0.5 mM Gadolinium chloride. These activities insensitive to ATPase, adenylate kinase alkaline phosphatase classical inhibitors. The K m values 464.2 ± 86.6 μM (mean ± SEM, n  = 4), 137.0 ± 31 μM  = 5) 44.8 ± 10.2 μM V max 655.0 ± 94.6 236.3 ± 27.2 177.6 ± 13.8 nmol inorganic phosphate min − 1 mg protein AMP, respectively. Using RT-PCR analysis identified mRNA two members ecto-nucleoside triphosphate diphosphohydrolase family (NTPDase 2 5) a 5′-nucleotidase. NTPDases enzymes tumor cells may be important regulate ratio adenine nucleotides/adenine nucleoside extracellularly, therefore motivating growth.