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Stability/activity tradeoffs in Thermusthermophilus HB27 laccase.
JBIC Journal of Biological Inorganic Chemistry ( IF 3 ) Pub Date : 2020-01-22 , DOI: 10.1007/s00775-020-01754-7
Jieun Shin 1 , Harry B Gray 1 , Jay R Winkler 1
Affiliation  

We report the temperature dependence of the formal potential of type 1 copper (CuT1) in Thermusthermophilus HB27 laccase. Employing [Ru(NH3)4(bpy)](PF6)2 (0.505 vs. NHE) as the redox titrant, we found that the CuT12+/+ potential decreased from approximately 480 to 420 mV (vs. NHE) as the temperature was raised from 20 to 65 °C. Of importance is that the ΔSrc° of − 120 J mol−1 K−1 is substantially more negative than those for other blue copper proteins. We suggest that the highly unfavorable reduction entropy is attributable to CuT1 inaccessibility to the aqueous medium. Although the active site residues are buried, which is critical for maintaining thermostability, the flexibility around CuT1 is maintained, allowing enzyme activity at ambient temperature

中文翻译:

嗜热菌 HB27 漆酶的稳定性/活性权衡。

我们报告了热菌HB27 漆酶中1 型铜 (Cu T1 )的形式电位的温度依赖性。使用 [Ru(NH 3 ) 4 (bpy)](PF 6 ) 2 (0.505 vs. NHE) 作为氧化还原滴定剂,我们发现 Cu T1 2+/+电位从大约 480 mV (vs. NHE ) 随着温度从 20°C 升高到 65°C。重要的是- 120 J mol -1  K -1的Δ S rc °明显比其他蓝铜蛋白的那些更负。我们认为非常不利的还原熵归因于 CuT1无法进入水性介质。尽管活性位点残基被掩埋,这对于保持热稳定性至关重要,但保留了 Cu T1周围的灵活性,允许酶在环境温度下活动
更新日期:2020-01-22
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