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Updated: Jul 13, 2026

Chemical Modification of the Tryptophan Residue in a Recombinant Ca2+-ATPase N-domain for Studying Tryptophan-ANS FRET
Published on: October 9, 2021
The role of tryptophan in the ferredoxin-dependent nitrite reductase of spinach
Jatindra N Tripathy1, Masakazu Hirasawa, Sung-Kun Kim
1Department of Chemistry and Biochemistry, Texas Tech University, 1 Circle Drive, Lubbock, TX 79409-1061, USA.
Abstract:
A system has been developed for expressing a His-tagged form of the ferredoxin-dependent nitrite reductase of spinach in Escherichia coli. The catalytic and spectral properties of the His-tagged, recombinant enzyme are similar, but not identical, to those previously observed for nitrite reductase isolated directly from spinach leaf. A detailed comparison of the spectral, catalytic and fluorescence properties of nitrite reductase variants, in which each of the enzyme's eight tryptophan residues has been replaced using site-directed mutagenesis by either aromatic or non-aromatic amino acids, has been used to examine possible roles for tryptophan residues in the reduction of nitrite to ammonia catalyzed by the enzyme.
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