Catalase has crucial role in adaptive response to H₂O₂. Main channel structure responsible for substrate selectivity was estimated to understand the relationship between the evolutionary direction of catalases from Exiguobacterium oxidotolerans and Psychrobacter piscatorii which survive in cold and high concentration of hydrogen peroxide, and their catalytic property. E. oxidotolerans catalase (EKTA) exhibited a higher ratio of compound I formation rate using peracetic acid (a substrate lager than H₂O₂)/catalase activity using H₂O₂ as the substrate than P. piscatori catalase (PKTA). It was considered that the ratio was attributed to the size of the amino acid residues locating at the bottle neck structure in the main channel. The differences in the ratio of the compound I formation rate with peracetic acid to catalase activity with H₂O₂ between the deeper branches in the phylogenetic tree in both EKTA and PKTA were large. This indicates that catalases from the hydrogen peroxide-tolerant bacteria have evolved in different directions, exhibiting effective catalytic activity and allowing broader substrates size or H₂O₂-specific substrate acceptability in EKTA and PKTA, respectively. It is considered that the main channel structure reflected the difference in the evolutionary direction of clade 1 and clade 3 catalases.

中文翻译：

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过氧化氢酶的主通道结构与耐冷过氧化氢细杆菌和冷杆菌进化方向的关系。

过氧化氢酶在对H ₂ O _{2 的}适应性反应中起关键作用。负责底物选择性主信道结构被估计为了解从过氧化氢酶的进化方向之间的关系微小杆菌oxidotolerans和嗜冷piscatorii这在寒冷和过氧化氢的高浓度的生存，以及它们的催化性能。乙。氧化耐受性过氧化氢酶 ( EKTA ) 使用过乙酸（比 H ₂ O ₂大的底物）/使用 H ₂ O ₂作为底物的过氧化氢酶活性比P表现出更高的化合物 I 形成率. piscatori过氧化氢酶 (PKTA)。认为该比率归因于位于主通道瓶颈结构处的氨基酸残基的大小。EKTA 和 PKTA 的系统发育树中较深分支之间的化合物 I 与过乙酸的形成速率与过氧化氢酶活性与 H ₂ O ₂的比率差异很大。这表明来自耐过氧化氢细菌的过氧化氢酶向不同方向进化，表现出有效的催化活性并允许更广泛的底物尺寸或 H ₂ O ₂- 分别在 EKTA 和 PKTA 中的特定底物可接受性。认为主要通道结构反映了进化枝1和进化枝3过氧化氢酶进化方向的差异。