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NADH:Fe(III)‐chelate reductase of maize roots is an active cytochrome b 5 reductase
Author(s) -
Sparla Francesca,
Bagnaresi Paolo,
Scagliarini Sandra,
Trost Paolo
Publication year - 1997
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(97)01073-9
Subject(s) - reductase , chemistry , chelation , biochemistry , enzyme , inorganic chemistry
Microsomal NADH:Fe(III)‐chelate reductase (NFR) of maize roots has been purified as a monomeric flavoprotein of 32 kDa with non‐covalently bound FAD. In the presence of NADH, NFR efficiently reduced the physiological iron‐chelate Fe(III)‐citrate ( K cat / K m(Fe(III)‐citrate) =6.0×10 6 M −1 s −1 ) with a sequential reaction mechanism. Purified NFR was totally inhibited by the sulfhydryl reagent PHMB at 10 −9 M, and it could use cyt b 5 as alternative electron acceptor with a maximal reduction rate as high as with Fe(III)‐citrate. We conclude that in maize roots the reduction of Fe(III)‐citrate is chiefly performed by a cytochrome b 5 reductase, mostly associated with intracellular membranes and in part with the plasma membrane.