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首页> 外文期刊>Biochemistry >Kinetic and Thermodynamic Features Reveal That Escherichia coli BCP Is an Unusually Versatile Peroxiredoxin
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Kinetic and Thermodynamic Features Reveal That Escherichia coli BCP Is an Unusually Versatile Peroxiredoxin

机译：动力学和热力学特征揭示了大肠杆菌BCP是一种异常通用的过氧氧化毒素

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摘要

In Escherichia coli, bacterioferritin comigratory protein (BCP) is a peroxiredoxin (Prx) that catalyzes the reduction of H_2O_2 and Ni organic hydroperoxides. This protein, along with plant PrxO is a founding member of one of the least studied subfamilies of Prxs. Recent structural data have suggested that proteins in the BCP/PrxQgroup can exist as monomers or dieters; we report here that, by analytical ultracentrifugation, both oxidized and reduced E. coli BCP behave as monomers in solution at concentrations as high as 200 μM. Unexpectedly, thioredoxin (Trx1)-dependent peroxidase assays conducted by stopped-flow spectroscopy demonstrated that V1~(max) interaction (K_m> 100 μM). At a physiologically reasonable Trxl concentration of 10 μM, the apparent K_m value for H_2O_2 is —8 sM, and overall, the V_(max)/K_m for H_2O_2, which remains constant at the various Trxl concentrations (consistent with a ping-pon nechanism), is —1.3 x 10~4 s~(-1) Our kinetic analyses demonstrated that BCP can utilize a variety of reducing substrates Including Trxl, Trx2, Grx1, and Grx3. BCP exhibited a high redox potential of —145.9 ± 3.2 mV, the highest to date observed fo Prx. Moreover, BCP exhibited a broad peroxide specificity, with comparable rates for H2O2 and cumene hydroperoxide. W determined a pK of —5.8 for the peroxidatic cysteine (Cys45) using both spectroscopic and activity titration data. These finding upport an important role for BCP in interacting with multiple substrates and remaining active under highly oxidizing cellula :onditions, potentially serving as a defense enzyme of last resort.
机译：在大肠杆菌中，菌丝焙烧蛋白的蛋白质（BCP）是催化H_2O_2和Ni有机氢过氧化物的还原的过氧杂菌素（PRX）。该蛋白质和植物PRXO是PRXS最不学习的亚颗粒的创始成员。最近的结构数据表明BCP / PRXQGroup中的蛋白质可以作为单体或节食者存在;我们在此报告，通过分析超速离心，氧化和降低的大肠杆菌BCP在浓度高达200μm的浓度下表现为溶液中的单体。出乎意料地，通过停止流动光谱传导的硫昔林（TRX1） - 依赖过氧化物酶测定证明了V1〜（最大）相互作用（K_m>100μm）。在物理上合理的TRXL浓度为10μm，H_2O_2的表观K_M值为-8MM，总体而言，H_2O_2的V_（MAX）/ K_M在各种TRXL浓度下保持恒定（与Ping-PON Necharism一致） ），IS1.3 x 10〜4 s〜（-1）我们的动力学分析证明，BCP可以利用各种还原基板，包括TRXL，TRX2，GRX1和GRX3。 BCP展示了-145.9±3.2 mV的高氧化还原电位，最高迄今为止观察到PRX。此外，BCP具有宽氧化物特异性，H 2 O 2和氢过氧化物的可比速率。 W使用光谱和活性滴定数据确定过氧化半胱氨酸（Cys45）的PK的-5.8。这些发现Upport在BCP与多种底物相互作用并在高氧化的Cellula下剩余活性的重要作用：onditions，可能用作最后手段的防御酶。

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  • 来源
    《Biochemistry》 |2011年第41期|共12页
  • 作者

    Stacy A. Reeves; Derek Parsonage; Kimberly J. Nelson; Leslie B. Poole;

  • 作者单位

    Department of Biochemistry Wake Forest School of Medicine Winston-Salem North Carolina 27157 United States;

    Department of Biochemistry Wake Forest School of Medicine Winston-Salem North Carolina 27157 United States;

    Department of Biochemistry Wake Forest School of Medicine Winston-Salem North Carolina 27157 United States;

    Department of Biochemistry Wake Forest School of Medicine Winston-Salem North Carolina 27157 United States;

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  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 生物化学;
  • 关键词

    Thermodynamic; Escherichia; Peroxiredoxin;

    机译：热力学;大肠杆菌;过氧杂志;

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