The hemocytes of the freshwater snail Viviparus ater have nitric oxide synthase (NOS) activity, as demonstrated by [H-3]citrulline and nitrite + nitrate formation. The enzyme is NADPH dependent and is competitively inhibited by the mammalian NOS inhibitor N-G-monomethyl-L-arginine (K-i = 4.7 mu M). The K-m for L-arginine is 2.5 mu M. 70% of the total activity is observed at very low free Ca2+ concentration (3 nM). LPS treatment increased total NOS activity 2.4 fold. The activity is partly present in the non-soluble fraction of hemocytes (24% and 8% in non-stimulated and LPS-stimulated snails, respectively). An antiserum to the C-terminal synthetic pentadecapeptide of the rat cerebellar NOS inhibited the enzyme activity in a concentration-dependent manner. This is the first biochemical demonstration of the existance of NOS activity in molluscan hemocytes, the cells responsible for defence mechanisms.

Nitric oxide synthase activity in molluscan hemocytes / Conte, Angela; Ottaviani, Enzo. - In: FEBS LETTERS. - ISSN 0014-5793. - STAMPA. - 365:(1995), pp. 120-124.

Nitric oxide synthase activity in molluscan hemocytes

CONTE, Angela;OTTAVIANI, Enzo
1995

Abstract

The hemocytes of the freshwater snail Viviparus ater have nitric oxide synthase (NOS) activity, as demonstrated by [H-3]citrulline and nitrite + nitrate formation. The enzyme is NADPH dependent and is competitively inhibited by the mammalian NOS inhibitor N-G-monomethyl-L-arginine (K-i = 4.7 mu M). The K-m for L-arginine is 2.5 mu M. 70% of the total activity is observed at very low free Ca2+ concentration (3 nM). LPS treatment increased total NOS activity 2.4 fold. The activity is partly present in the non-soluble fraction of hemocytes (24% and 8% in non-stimulated and LPS-stimulated snails, respectively). An antiserum to the C-terminal synthetic pentadecapeptide of the rat cerebellar NOS inhibited the enzyme activity in a concentration-dependent manner. This is the first biochemical demonstration of the existance of NOS activity in molluscan hemocytes, the cells responsible for defence mechanisms.
365
120
124
Nitric oxide synthase activity in molluscan hemocytes / Conte, Angela; Ottaviani, Enzo. - In: FEBS LETTERS. - ISSN 0014-5793. - STAMPA. - 365:(1995), pp. 120-124.
Conte, Angela; Ottaviani, Enzo
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11380/305910
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