
%0 Journal Article
%A Ledgard, SF 
%A Woo, KC 
%A Bergersen, FJ 
%T Isotopic Fractionation During Reduction of Nitrate and Nitrite by Extracts of Spinach Leaves
%J Functional Plant Biology
%D 1985/12/01
%V 12
%N 6
%P 631-640
%K 
%R https://doi.org/10.1071/PP9850631
%U https://www.publish.csiro.au/paper/PP9850631 
%X The isotopic fractionations of nitrogen during the reduction of NO3- and NO2- in a cytosolic fraction and in a chloroplast preparation from spinach (Spinacia oleracea L.) leaves were determined. The reduction of NO3- to NH3 was studied using a reconstituted system containing cytosolic extract and intact chloroplasts, while a chloroplast system was used for NO2- reduction. In the reconstituted systems the ratio of nitrate reductase activity to nitrite reductase activity had a large effect on the relative amounts of NO2- and NH3 formed. Ammonia predominated when the nitrate reductase to nitrite reductase activity ratio was 1 : 5 and this ratio was used in the isotopic fractionation studies. Significant isotopic fractionation of N was observed in the reconstituted system but not in the chloroplast system. This indicates that the observed isotopic fractionation was associated with the reduction of NO3- to NO2- by nitrate reductase. The isotopic fractionation (i.e. &#948;15Nproduct - &#948;15Nsubstrate) for this reaction was - 15&#8240;. 
