Nitrate reductase (15)N discrimination in Arabidopsis thaliana, Zea mays, Aspergillus niger, Pichea angusta, and Escherichia coli.

ABSTRACT: Stable (15)N isotopes have been used to examine movement of nitrogen (N) through various pools of the global N cycle. A central reaction in the cycle involves the reduction of nitrate (NO(-) 3) to nitrite (NO(-) 2) catalyzed by nitrate reductase (NR). Discrimination against (15)N by NR is a major determinant of isotopic differences among N pools. Here, we measured in vitro (15)N discrimination by several NRs purified from plants, fungi, and a bacterium to determine the intrinsic (15)N discrimination by the enzyme and to evaluate the validity of measurements made using (15)N-enriched NO(-) 3. Observed NR isotope discrimination ranged from 22 to 32‰ (kinetic isotope effects of 1.022-1.032) among the different isozymes at natural abundance (15)N (0.37%). As the fractional (15)N content of sub

SUBMITTER: Carlisle E 

PROVIDER: S-EPMC4078254 | biostudies-literature | 2014

REPOSITORIES: biostudies-literature