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 X 106 M-1 s-1) with a sequential reaction mechanism. Purified NFR was totally inhibited by the sulfhdryl reagent PHMB at 10-9 M, and it could use cyt b5 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 b5 reductase, mostly associated with intracellular membranes and in part with the plasma membrane.
NADH: Fe(III)-chelate reductase of maize roots is an active cytochrome b5 reductase / Sparla F.; Bagnaresi P.; Scagliarini S.; Trost P.. - In: FEBS LETTERS. - ISSN 0014-5793. - STAMPA. - 414:3(1997), pp. 571-575. [10.1016/S0014-5793(97)01073-9]
NADH: Fe(III)-chelate reductase of maize roots is an active cytochrome b5 reductase
Sparla F.;Bagnaresi P.;Scagliarini S.;Trost P.
1997
Abstract
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 X 106 M-1 s-1) with a sequential reaction mechanism. Purified NFR was totally inhibited by the sulfhdryl reagent PHMB at 10-9 M, and it could use cyt b5 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 b5 reductase, mostly associated with intracellular membranes and in part with the plasma membrane.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
