We explore the significance of phenylalanine outside of the phosphotriesterase (PTE) dimer interface through mutagenesis studies and computational modeling. Previous studies have demonstrated that the residue-specific incorporation of para-fluorophenylalanine (pFF) into PTE improves stability, suggesting the importance of phenylalanines in stabilization of the dimer. However, this comes at a cost of decreased solubility due to pFF incorporation into other parts of the protein. Motivated by this, eight single solvent-exposed phenylalanine mutants are evaluated via ROSETTA and good correspondence between experiments and these predictions is observed. Three residues, F304, F327, and F335, appear to be important for PTE activity and stability, even though they do not reside in the dimer interface region or active site. While the remaining mutants do not significantly affect structure or activity, one variant, F306L, reveals improved activity at ambient and elevated temperatures. These studies provide further insight into role of these residues on PTE function and stability.

中文翻译：

---

二聚体界面以外的苯丙氨酸对磷酸三酯酶稳定性和功能的影响

我们通过诱变研究和计算模型探索了磷酸三酯酶（PTE）二聚体界面之外的苯丙氨酸的重要性。以前的研究已经证明，的特定残基掺入第-fluorophenylalanine（p FF）到PTE提高了稳定性，表明苯丙氨酸的二聚物的稳定化的重要性。但是，这是由于将p FF掺入蛋白质的其他部分而导致溶解度降低的代价。因此，通过 ROSETTA评估了八个暴露于溶剂中的单一苯丙氨酸突变体并观察到实验与这些预测之间的良好对应关系。F304，F327和F335这三个残基似乎对PTE活性和稳定性很重要，即使它们不位于二聚体界面区域或活性位点也是如此。虽然其余的突变体不会显着影响结构或活性，但一种变体F306L在环境温度和高温下显示出改善的活性。这些研究为这些残基对PTE功能和稳定性的作用提供了进一步的了解。