Author(s):
Aníbal, J. 
; Bicho, M.
Date: 1996
Persistent ID: http://hdl.handle.net/10400.1/2772
Origin: Sapientia - Universidade do Algarve
Document details
Influence of oxidative stress produced by nitrite in the activity of methaemogl...
Description
Nitrite induces the oxidation of the haemoglobin forming methaemoglobin, which is nonfunctional. To oppose this formation fishes have an enzyme that reverses the process called methaemoglobin reductase. In vitro activity of the methaemoglobin reductase was determined, in the presence and absence of nitrite in two marine fishes (toadfish, Halobatrachus didactylus and gilt head sea breams Sparus aurata). The KM and Vmax were determined through the Eisenthal and Cornish-Bowden Plot. The basis for this study is that the methaemoglobin reductase system has very active ferricyanide reductase activity. Halobatrachus didactylus showed a significant decrease in its values of methaemoglobin reductase activity with the increase in nitrite concentration (38.9; l6.3; 14.5: l4.0 and 12.3 mmol NAD+/min/gHB respectively to 0; 1; 3; 6 and 9 mM N02). In Sparus aurata, the nitrite didn't induced significant variations in the methaemoglobin reductase activity (27.8; 27.1; 25.3; 22.3 and 18.7 mmol NAD+/min/gHB respectively to 0; 1; 3; 6 and 9 mM N02). This results probably indicate fish to have other paths opposing to the formation of methaemoglobin, rather than the enzymatic system of the methaemoglobin reductase. At the moment the meaning of this of this different behaviour is not known.
Nitrite induces the oxidation of the haemoglobin forming methaemoglobin, which is nonfunctional. To oppose this formation fishes have an enzyme that reverses the process called methaemoglobin reductase. In vitro activity of the methaemoglobin reductase was determined, in the presence and absence of nitrite in two marine fishes (toadfish, Halobatrachus didactylus and gilt head sea breams Sparus aurata). The KM and Vmax were determined through the Eisenthal and Cornish-Bowden Plot. The basis for this study is that the methaemoglobin reductase system has very active ferricyanide reductase activity. Halobatrachus didactylus showed a significant decrease in its values of methaemoglobin reductase activity with the increase in nitrite concentration (38.9; l6.3; 14.5: l4.0 and 12.3 mmol NAD+/min/gHB respectively to 0; 1; 3; 6 and 9 mM N02). In Sparus aurata, the nitrite didn't induced significant variations in the methaemoglobin reductase activity (27.8; 27.1; 25.3; 22.3 and 18.7 mmol NAD+/min/gHB respectively to 0; 1; 3; 6 and 9 mM N02). This results probably indicate fish to have other paths opposing to the formation of methaemoglobin, rather than the enzymatic system of the methaemoglobin reductase. At the moment the meaning of this of this different behaviour is not known.
Document Type
Conference Object
Language English
Language English
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