Thermodynamics of the dimer-decamer transition of reduced human and plant 2-Cys peroxiredoxin
Thermodynamics of the dimer-decamer transition of reduced human and plant 2-Cys peroxiredoxin
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DOI：
10.1021/bi8002956
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发表时间：
2008-07-08
期刊：
影响因子：
2.9
通讯作者：
Dietz, Karl-Josef
中科院分区：
文献类型：
--
作者：
Barranco-Medina, Sergio;Kakorin, Sergej;Dietz, Karl-Josef
等温滴定量热法（ITC）是一种研究蛋白质复合物自缔合过程的有力技术，通过直接测量二聚体-二聚体相互作用的热力学参数来测量过氧化物氧还蛋白寡聚化。通过在各种氧化还原条件下逐步注射到反应容器中，对来自智人、拟南芥和豌豆的重组经典2-半胱氨酸过氧化物氧还蛋白以及羧基末端截短的变体进行ITC分析。直接测量的十聚体二聚体平衡的还原过氧化物氧还蛋白揭示了一个临界浓度在非常低的微摩尔范围内。这些数据表明，在这个临界过渡浓度以上，一个核促进组装的合作组装。而突然的过渡表明，组装过程不发生低于临界过渡浓度，而低聚反应是有效地触发以上it. The测得的焓的大小证实了过氧化物氧还蛋白低聚反应的吸热性质。来自不同物种的过氧化物氧还蛋白多肽之间没有形成杂合物。我们的结论是，一个功能性的限制保守的二聚体-十聚体过渡与高度相似的临界过渡浓度，尽管出现的序列变化在进化过程中。
Isothermal titration calorimetry (ITC) is a powerful technique for investigating self-association processes of protein complexes and was expected to reveal quantitative data on., peroxiredoxin oligomerization by directly measuring the thermodynamic parameters of dimer-dimer interaction. Recombinant classical 2-cysteine peroxoredoxins from Homo sapiens, Arabidopsis thaliana, and Pisum sativum as well as a carboxy-terminally truncated variant were subjected to ITC analysis by stepwise injection into the reaction vessel under various redox conditions. The direct measurement of the decamer-dimer equilibrium of reduced peroxiredoxin revealed a critical concentration in the very low micromolar range. The data suggest a cooperative assembly above this critical transition concentration where a nucleus facilitates assembly. The rather abrupt transition indicates that assembly processes do not occur below the critical transition concentration while oligomerization is efficiently triggered above it. The magnitude of the measured enthalpy confirmed the endothermic nature of the peroxiredoxin oligomerization. Heterocomplexes between peroxiredoxin polypeptides from different species were not formed. We conclude that a functional constraint conserved the dimer-decamer transition with highly similar critical transition concentrations despite emerging sequence variation during evolution.