Abstract
An enzyme, which catalyzes the decomposing reaction of nitroglycol or nitroglycerin into inorganic nitrate and ethylene glycol mononitrate, was found in the blood and in the liver. This enzyme was named as " Nitrate forming enzyme ". Both the enzymes in the blood and in the liver showed the same properties, but they were clearly dif-ferent from nitrite forming enzyme reported by Heppel and Hilmore.
Nitrate forming enzyme was extracted from acetone powder of the liver and par-tially purified by ammonium sulfate fractionation.
The value of Michaelis constant of the enzyme was about 3.0 mM at pH 7.4 and 37°C, and the value of optimum pH was 6.3. This enzyme acts on nitroglycol without reduced glutathione (GSH) as a co-factor, although nitrite forming enzyme can not act in the absence of GSH. A significant property of this enzyme is the inactivation by the substrate itself, and it appears at very low concentrations of nitroglycol.
