NADH:Fe(III)‐chelate reductase of maize roots is an active cytochrome b 5 reductase

FEBS Letters

Sparla, Francesca¹  Scagliarini, Sandra¹  Trost, Paolo¹  Bagnaresi, Paolo¹ 

[1] Dipartimento di Biologia Evoluzionistica Sperimentale, Università di Bologna, Via Irnerio 42, 40126 Bologna, Italy

关键词: Iron reduction;    NADH:Fe(III)-chelate reductase;    Fe(III)-citrate;    Cytochrome b 5 reductase;    Zea mays;    NFR;    NADH:Fe(III)-chelate reductase;    b 5R;    cytochrome b 5 reductase;    ICM;    intracellular membranes;    PHMB;    p-hydroxymercuribenzoic acid;    PM;    plasma membrane;   

DOI  :  10.1016/S0014-5793(97)01073-9

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

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)}=6.0×10⁶ 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.

【 授权许可】

Unknown