Nucleotidase activities in membrane preparations of nervous ganglia and digestive gland of the snail Helix aspersa.
Nucleotide-metabolizing enzymes play an important role in the regulation of nucleotide levels. In the present report, we demonstrated an enzyme activity with different kinetic properties in membrane preparations of the nervous ganglia and digestive gland from Helix aspersa. ATPase and ADPase activities were dependent on Ca2+ and Mg2+ with pH optima approximately 7.2 and between 6.0 and 8.0 in digestive gland and nervous ganglia, respectively. The enzyme activities present in membrane preparations of these tissues preferentially hydrolyzed triphosphate nucleotides. In nervous ganglia, the enzyme was insensitive to the classical ATPases inhibitors. In contrast, in digestive gland, N-ethylmaleimide (NEM) produced 45% inhibition of Ca(2+)-ATP hydrolysis. Sodium azide, at 100 microM and 20 mM, inhibited Mg(2+)-ATP hydrolysis by 36% and 55% in digestive gland, respectively. The presence of nucleotide-metabolizing enzymes in these tissues may be important for the modulation of nucleotide and nucleoside levels, controlling their actions on specific purinoceptors in these species.
Borges
Eliane
E
Departamento de Ciências Fisiológicas, Faculdade de Biociências, Laboratório de Pesquisa Bioquímica, Pontifícia Universidade Católica do Rio Grande do Sul, Avenida Ipiranga, 6681, Caixa postal 1429, 90619-900, Porto Alegre, RS, Brazil.
Cognato
Giana de Paula
Gde P
Vuaden
Fernanda Cenci
FC
Bogo
Maurício Reis
MR
Fauth
Maria da Graça
Mda G
Bonan
Carla Denise
CD
Dias
Renato Dutra
RD
D000244:Adenosine Diphosphate / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D002413:Cations, Divalent; D002462:Cell Membrane / Q000201:enzymology*; D004063:Digestion; D017952:Ganglia, Invertebrate / Q000201:enzymology*; D005753:Gastric Mucosa / Q000201:enzymology*; D006372:Helix, Snails / Q000201:enzymology*; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D007700:Kinetics; D009708:Nucleotidases / Q000378:metabolism*
D002413:Cations, Divalent; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D009708:Nucleotidases