Ferroxidase activity of recombinant Desulfovibrio vulgaris rubrerythrin
Ferroxidase activity of recombinant Desulfovibrio vulgaris rubrerythrin
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DOI：
10.1007/s007750050024
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发表时间：
1996-02-01
影响因子：
3
通讯作者：
Cui, XY
中科院分区：
文献类型：
--
作者：
Bonomi, F;Kurtz, DM;Cui, XY
赤藓红蛋白（Rr）是在厌氧硫酸盐还原菌中发现的一种功能未知的非血红素铁蛋白。Rr是独特的，在同一个蛋白质中同时含有rubredoxin型FeS 4和diiron-oxo位点。本文所述的结果表明，对于重组蛋白：（a）Rr催化Fe 2+通过O-2氧化为Fe 3+，即，Rr具有铁氧化酶活性，（B）FeS 4和Rr蛋白的二铁结构域都是铁氧化酶活性所需的，（c）在过量Fe 2+和O-2的情况下，这种氧化的初始速率在[Rr]中似乎是一级的，并且不依赖于起始[Fe 2 +]高于30 μ M，（d）Fe 3+以能够快速掺入卵转铁蛋白的铁结合位点的形式产生，和（e）在亚基基础上，Rr的铁氧化酶活性与已发表的脱铁铁蛋白的铁氧化酶活性相当。Rr的铁氧化酶活性通过在315 nm（其位于氧化和还原Rr的等吸光点附近）处吸光度的增加速率或通过使用脱铁转铁蛋白作为Fe 3+受体并测量在460 nm处二铁转铁蛋白形成的速率和程度来监测。没有聚铁氧氢氧化物聚集体出现与铁氧化酶反应后的Rr。一个截短形式的Rr只含有二铁结构域有很少或没有铁氧化酶活性。Rr可以作为一组酶的一个组成部分，在细菌短暂暴露于空气期间，将O-2和Fe 2+的反应产物引导到无毒途径上。
Rubrerythrin (Rr) is the trivial name given to a non-heme iron protein of unknown function which has been found in anaerobic sulfate-reducing bacteria. Rr is unique in containing both rubredoxin-type FeS4 and diiron-oxo sites in the same protein. The results described here demonstrate for the recombinant protein that: (a) Rr catalyzes oxidation of Fe2+ to Fe3+ by O-2, i.e., Rr has ferroxidase activity, (b) both FeS4 and diiron domains of the Rr protein are required for ferroxidase activity, (c) with excess Fe2+ and O-2 the initial rate of this oxidation appears to be first order in [Rr] and independent of starting [Fe2+] above 30 mu M, (d) the Fe3+ is produced in a form which is capable of rapid incorporation into the iron-binding site of ovotransferrin, and (e) the ferroxidase activity of Rr is comparable to that of published ferroxidase activities of apoferritins on a subunit basis. Ferroxidase activity of Rr was monitored either by the rate of increase in absorbance at 315 nm (which lies near an isosbestic point for oxidized and reduced Rr) or by using apoovotransferrin as Fe3+ acceptor, and measuring the rate and extent of diferric transferrin formation at 460 mn. No polyironoxyhydroxide aggregates appeared to associate with Rr after the ferroxidase reaction. A truncated form of Rr containing only the diiron domain had little or no ferroxidase activity. Rr could function as one component of a set of enzymes which channels the reaction products of O-2 and Fe2+ onto a non-toxic pathway during transient exposure of the bacteria to air.