Department of Microbiology, Science and Research Branch, Islamic Azad University, Tehran, Iran.
Department of Biochemistry, Sanandaj Branch, Islamic Azad University, Sanandaj, Iran.
Med Hypotheses. 2018 Mar;112:7-17. doi: 10.1016/j.mehy.2018.01.004. Epub 2018 Jan 30.
L-Asparaginases (ASNase) belong to a family of amidohydrolases, have both asparaginase and glutaminase activity. Acute lymphocytic leukemia (ALL) is an outrageous disease worldwide. Bacterial ASNase has been used for the treatment of ALL. Glutaminase activity of enzyme causes some side effect and it is not essential for anticancer activity. The aim of this study was engineering of Escherichia coli asparaginase II to find a mutant with reduced glutaminase activity by molecular docking, molecular dynamics (MD) and QM-MM (Quantum mechanics molecular dynamics) simulations. Residues with low free energy of binding to Asn and high free binding energy to Gln were chosen for mutagenesis. Then, a mutant with higher glutaminase free binding energy was selected for further studies. Additionally, the MD simulation and QM-MM computation of wild type (WT) were employed and the selected mutated ASNase were analyzed and discussed. Our data showed that V27T is a good candidate to reduction the glutaminase activity, while has no remarkable effect on asparaginase activity of the enzyme. The simulation analysis revealed that V27T mutant is more stable than WT and mutant simulation was successful completely. QM-MM results confirmed the successfulness of our mutagenesis.
L-天冬酰胺酶（ASNase）属于酰胺水解酶家族，具有天冬酰胺酶和谷氨酰胺酶活性。急性淋巴细胞白血病（ALL）是一种全球性的恶性疾病。细菌 ASNase 已被用于 ALL 的治疗。酶的谷氨酰胺酶活性会引起一些副作用，并且对抗癌活性不是必需的。本研究的目的是通过分子对接、分子动力学（MD）和 QM-MM（量子力学分子动力学）模拟工程化大肠杆菌天冬酰胺酶 II，以找到一种突变体，其谷氨酰胺酶活性降低。选择与 Asn 结合自由能低、与 Gln 结合自由能高的残基进行突变。然后，选择具有更高谷氨酰胺酶自由结合能的突变体进行进一步研究。此外，还对野生型（WT）进行了 MD 模拟和 QM-MM 计算，并对选定的突变 ASNase 进行了分析和讨论。我们的数据表明，V27T 是降低谷氨酰胺酶活性的一个很好的候选者，同时对酶的天冬酰胺酶活性没有显著影响。模拟分析表明，V27T 突变体比 WT 更稳定，突变体模拟完全成功。QM-MM 结果证实了我们诱变的成功。
