On the two iron centers of desulfoferrodoxin

FEBS Letters

Hagen, Wilfred R.¹  Verhagen, Marc F.J.M.¹  Wolbert, Ronnie B.G.¹  Kolkman, Joost A.¹  Voorhorst, Wilfried G.B.¹ 

[1] Department of Biochemistry, Agricultural University, Dreijenlaan 3, NL-6703 HA Wageningen, The Netherlands

关键词: Bioelectrochemistry;    EPR;    Rubredoxin;    Redox;    Desulfovibrio vulgaris (H);   

DOI  :  10.1016/0014-5793(93)81599-U

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Desulfoferrodoxin from Desulfovibrio vulgaris, strain Hildenborough, is a homodimer of 28 kDa; it contains two Fe atoms per 14.0 kDa subunit. The N-terminal amino-acid sequence is homogeneous and corresponds to the previously described Rbo gene, which encodes a highly charged 14 kDa polypeptide without a leader sequence. Although one of the two iron centers, Fe_A, has previously been described as a ‘strained rubredoxin-like’ site, EPR of the ferric form proves very similar to that of the pentagonal bipyramidally coordinated iron in ferric complexes of DTPA, diethylenetriaminepentaacetic acid: both systems have spin S = and rhombicity E/D = 0.08. Unlike the Fe site in rubredoxin the Fe_A site in desulfoferrodoxin has a pH dependent midpoint potential with pK _ox= 9.2 and pK _red = 5.3. Upon reduction (E _m,7.5 = +2 mV) Fe_A exhibits an unusually sharp S = 2 resonance in parallel-mode EPR. The second iron, Fe_B, has S = and E/D = 0.33; upon reduction (E _m,7.5 = +90 mV) Fe_B turns EPR-silent.

【 授权许可】

Unknown