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首页> 外文期刊>Biochemistry >New insights into the heme cavity structure of catalase-peroxidase: a spectroscopic approach to the recombinant synechocystis enzyme and selected distal cavity mutants.
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New insights into the heme cavity structure of catalase-peroxidase: a spectroscopic approach to the recombinant synechocystis enzyme and selected distal cavity mutants.

机译：过氧化氢酶-过氧化物酶血红素腔结构的新见解：一种光谱方法，用于重组突囊藻酶和选定的远端腔突变体。

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Catalase-peroxidases (KatGs) are heme peroxidases with homology to yeast cytochrome cperoxidase (CCP) and plant ascorbate peroxidases (APXs). KatGs exhibit a peroxidase activity of broad specificity and a high catalase activity, which strongly depends on the presence of a distal Trp as part of the conserved amino acid triad Arg-Trp-His. By contrast, both CCP and APX do not have a substantial catalase activity despite the presence of the same triad. Thus, to elucidate structure-function relationships of catalase-peroxidases (for which no crystal structure is available at the moment), we performed UV-Vis and resonance Raman studies of recombinant wild-type KatG from the cyanobacterium SynechocystisPCC 6803 and the distal side variants (His123-->Gln, Glu; Arg119-->Ala, Asn; Trp122-->Phe, Ala). The distal cavity of KatG is very similar to that of the other class I peroxidases. A H-bond network involving water molecules and the distal Trp, Arg, and His is present, which connects the distal and proximal sides of the heme pocket. However, distal mutation not only affects the heme Fe coordination state and perturbs the proximal Fe-Im bond, as previously observed for other peroxidases, but also alters the stability of the heme architecture. The charge of the distal residues appears particularly important for maintaining the heme architecture. Moreover, the Trp plays a significant role in the distal H-bonding, much more pronounced than in CCP. The relevance of these findings for the catalase activity of KatG is discussed in light of the complete loss of catalase activity in the distal Trp mutants.
机译：过氧化氢酶过氧化物酶（KatGs）是血红素过氧化物酶，与酵母细胞色素过氧化物酶（CCP）和植物抗坏血酸过氧化物酶（APXs）具有同源性。 KatGs表现出广泛的过氧化物酶活性和高的过氧化氢酶活性，这在很大程度上取决于作为保守氨基酸三联体Arg-Trp-His一部分的远端Trp的存在。相反，尽管存在相同的三联体，CCP和APX都没有实质的过氧化氢酶活性。因此，为阐明过氧化氢酶-过氧化物酶的结构-功能关系（目前尚无晶体结构），我们对蓝细菌SynechocystisPCC 6803及其远端变体进行了重组野生型KatG的UV-Vis和共振拉曼研究。 （His123-> Gln，Glu; Arg119-> Ala，Asn; Trp122-> Phe，Ala）。 KatG的远端腔与其他I类过氧化物酶非常相似。存在包含水分子和远端Trp，Arg和His的H键网络，该网络连接血红素袋的远端和近端。但是，远端突变不仅会影响血红素铁的配位状态并扰乱近端的Fe-Im键（如先前对其他过氧化物酶所观察到的），而且还会改变血红素结构的稳定性。远端残基的电荷对于维持血红素结构特别重要。而且，Trp在远侧H键中起着重要作用，比在CCP中更明显。鉴于远端Trp突变体中过氧化氢酶活性的完全丧失，讨论了这些发现与KatG的过氧化氢酶活性的相关性。

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