| 11742758 |
Da Silva RS, de Paula Cognato G, Bogo MR, da Graca Fauth M, Fin CA, Thome JW, Bonan CD, Dutra Dias R: Unique Ca (2+)-activated ATPase in the nervous ganglia of Phyllocaulis soleiformis (Mollusca). Comp Biochem Physiol B Biochem Mol Biol. 2002 Jan;131(1):55-61.
Nucleotide-metabolizing enzymes play important roles in the regulation of intracellular and extracellular nucleotide levels. We studied ATPase activity in the nervous ganglia of Phyllocaulis soleiformis, a terrestrial slug. The ATPase was divalent cation-dependent, with a maximal rate for ATP hydrolysis at pH 6.0 and 7.2 in the presence of Ca (2+) (5 mM). Mg (2+)-ATPase activity was only 26% of the activity observed in the presence of Ca (2+) (5 mM). ZnCl2 (10 mM) produced a significant inhibition of 70%. Ca (2+)-ATPase activity was insensitive to the classical ATPase inhibitors ouabain, N-ethylmaleimide, orthovanadate and sodium azide. Levamisole, an inhibitor of alkaline phosphatase, was ineffective. Among nucleotides, ATP was the best substrate. The apparent K (m) ((ATP)) for Ca (2+)-ATPase was 348+/-84 microM ATP and the V (max) was 829+/-114 nmol Pi min (-1) mg (-1) protein. The P. soleiformis ganglial ATPase does not appear to fit clearly into any of the previously described types of Ca (2+)-ATPases. |
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