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Catalytic Adaptation of Psychrophilic Elastase

机译：催化改编心脏弹性酶活性

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摘要

The class I pancreatic elastase from Atlantic salmon is considered to be a cold-adapted enzyme in view of the cold habitat, the reduced thermostability of the enzyme, and the fact that it is faster than its mesophilic porcine counterpart at room temperature. However, no experimental characterization of its catalytic properties at lower temperatures has actually been reported. Here we use extensive computer simulations of its catalytic reaction, at different temperatures and with different peptide substrates, to compare its characteristics with those of porcine pancreatic elastase, with which it shares 67% sequence identity. We find that both enzymes have a preference for smaller aliphatic residues at the P1 position, while the reaction rate with phenylalanine at P1 is predicted to be substantially lower. With the former class of substrates, the calculated reaction rates for salmon enzyme are consistently higher than those of the porcine ortholog at all temperatures examined, and the difference is most pronounced at the lowest temperature. As observed for other cold-adapted enzymes, this is caused by redistribution of the activation free energy in terms of enthalpy and entropy and can be linked to differences in the mobility of surface-exposed loops in the two enzymes. Such mobility changes are found to be reflected by characteristic sequence conservation patterns in psychrophilic and mesophilic species. Hence, calculations of mutations in a single surface loop show that the temperature dependence of the catalytic reaction is altered in a predictable way.
机译：考虑到诸如冷居栖息地，酶的降低的热稳定性以及比其室温下的嗜合猪对应物更快的事实，鲑鱼胰蛋白酶胰蛋白酶是一种冷适应的酶。然而，实际上没有报道在较低温度下的其催化性质的实验表征。在这里，我们在不同的温度和不同的肽基材上使用催化反应的大量计算机模拟，以将其与猪胰腺弹性蛋白酶的特性进行比较，其中序列同一性67％。我们发现两个酶都偏好于P1位置的较小脂族残基，而在P1处的反应速率预测基本上更低。对于前一类底物，鲑鱼酶的计算反应速率始终高于所检查的所有温度的猪晶片的反应速率，并且在最低温度下差异最为明显。如对于其他冷适应酶所观察到，这是由焓和熵的激活自由能再分布引起的，并且可以与两种酶中表面暴露环的迁移率的差异联系起来引起的。发现这种迁移率变化被心理和嗜合物种中的特征序列保护模式反映。因此，单个表面环路中的突变的计算表明催化反应的温度依赖性以可预测的方式改变。

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  • 来源
    《Biochemistry》 |2018年第20期|共10页
  • 作者

    Jaka So?an; Masoud Kazemi; Geir Villy Isaksen; Bj?rn Olav Brandsdal; Johan ?qvist;

  • 作者单位

    Department of Cell and Molecular Biology Uppsala University;

    Department of Cell and Molecular Biology Uppsala University;

    Department of Cell and Molecular Biology Uppsala University;

    Hylleraas Centre for Quantum Molecular Sciences Department of Chemistry University of Troms?;

    Department of Cell and Molecular Biology Uppsala University;

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  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 生物化学;
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