同类的乙碳酸酶选择Fe (II) 或Mn (II) 作为催化辅因子
Krista A Shisler1, William M Kincannon2, Jenna R Mattice2
1Institute of Biological Chemistry, Washington State University, Pullman, Washington, USA.
mBio
|December 21, 2023
概括
乙碳氧化酶 (ACs) 使用不同的金属, (Mn(II)) 或铁 (Fe(II) 进行催化,这违背了典型的金属稳定性预测. 细微的蛋白质结构差异决定了这种金属选择性.
科学领域:
- 生物化学 生物化学
- 酶学 是一种酶学.
- 生物有机化学 生物有机化学
背景情况:
- 乙碳氧酶 (ACs) 是对将乙和二碳酸盐转化为乙酸盐至关重要的酶,需要金属辅助因子和ATP.
- 来自*Xanthobacter autotrophicus*和*Aromatoleum aromaticum*的两个同类AC显示出显著的序列相同性 (68%),但已经提出利用不同的催化金属.
- 欧文-威廉姆斯系列预测过渡金属复合体稳定性的一般趋势,这似乎被这些AC的金属偏好所挑战.
研究的目的:
- 为了研究来自*Xanthobacter autotrophicus*和*Aromatoleum aromaticum*的两个同类碳酸酶 (ACs) 的金属依赖性.
- 为了确定具体的金属离子 (Mn ((II) 或Fe ((II)) 纳入这些ACs的活性位点.
- 阐明这些酶中金属歧视背后的机制,特别是根据欧文-威廉姆斯系列.
主要方法:
- 在相同的条件下,在*Escherichia coli*中表达两种AC.
- 使用Mn (II) 或Fe (II) 的化和化实验.
- 使用电子磁共振 (EPR) 和Mössbauer光谱仪进行表征,以识别结合的金属离子.
主要成果:
- 两种AC都成功地在没有外部帮助的情况下将它们的相关金属 (Mn(II) 或Fe(II)) 纳入,证明了内在的金属选择.
- 尽管有热力学偏好,但每个交流电源在其活性部位选择性地结合了一种不同的金属 (Mn (II) 或Fe (II)).
- 催化活性与正确结合的金属具有独特的关联,尽管这两种金属都可能发挥易斯酸性作用.
- 同类AC中的微妙结构变化作为Mn (II) 或Fe (II) 的选择性过器.
结论:
- 乙碳氧化酶对特定的双价第一列过渡金属具有显著的选择性,比热力学上更受欢迎的选项更喜欢Mn (II) 或Fe (II).
- 蛋白质结构在确定金属离子特异性方面发挥着关键作用,作为选择性过器.
- 了解这些金属区分机制对于推进金属介导催化和设计新型金属催化剂的知识至关重要.
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