On the Nitrate Reductase of Cattle Liver

Abstract

A preparation of nitrate reductase was readily obtained from cattle liver homogenate by repeated fractionation with ammonium sulfate followed by treatment with Ca phosphate gel. The activity of the reductase was exhibited by conjunction with acetaldehyde, which could be replaced by mitochondria. Some properties of the enzyme preparation are described here: opt. pH 5.8, opt. temp. 55°C, absorptions at 262mμ and 405mμ, sensitivity against metal and SH reagents and the participation of ferrous salt in activity. Discussions are presented on the hydrogen donating system, especially on the difference of the principle of enzymatic nitrate reduction from aldehyde and xanthine oxidases.