The 2.2 A resolution structure of the catalase-peroxidase KatG from Synechococcus elongatus PCC7942.
The 2.2 A resolution structure of the catalase-peroxidase KatG from Synechococcus elongatus PCC7942.
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来自细长聚球藻 PCC7942 的过氧化氢酶-过氧化物酶 KatG 的 2.2 A 解析结构。
DOI：
10.1107/s2053230x14002052
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发表时间：
2014
期刊：
影响因子：
--
通讯作者：
T. Tada
中科院分区：
文献类型：
--
作者：
S. Kamachi;K. Wada;M. Tamoi;S. Shigeoka;T. Tada
用分子置换法解析了细长聚球藻7942（SeKatG）过氧化氢酶-过氧化物酶的晶体结构，在2.2 nm分辨率下，Rwork为16.8%，Rfree为20.6%。 的不对称单位组成的过氧化氢酶-过氧化物酶分子，包括一个原卟啉IX血红素部分和两个钠离子只有一个亚基。形成了典型的KatG共价加合物Met 248-Tyr 222-Trp 94，其是过氧化氢酶活性的关键结构元件。通过双重对称操作产生晶体学等效亚基以形成功能性二聚体。二聚体的整体结构与其他KatG非常相似。一个钠离子位于近端Trp 314附近。近端阳离子位点的位置和构型与典型的过氧化物酶如抗坏血酸过氧化物酶的位置和构型非常相似。这些特征可以为酶促反应过程中自由基定位/离域的行为提供结构基础。
The crystal structure of catalase-peroxidase from Synechococcus elongatus PCC7942 (SeKatG) was solved by molecular replacement and refined to an Rwork of 16.8% and an Rfree of 20.6% at 2.2 Å resolution. The asymmetric unit consisted of only one subunit of the catalase-peroxidase molecule, including a protoporphyrin IX haem moiety and two sodium ions. A typical KatG covalent adduct was formed, Met248–Tyr222–Trp94, which is a key structural element for catalase activity. The crystallographic equivalent subunit was created by a twofold symmetry operation to form the functional dimer. The overall structure of the dimer was quite similar to other KatGs. One sodium ion was located close to the proximal Trp314. The location and configuration of the proximal cation site were very similar to those of typical peroxidases such as ascorbate peroxidase. These features may provide a structural basis for the behaviour of the radical localization/delocalization during the course of the enzymatic reaction.