Center for Structural Biology, Center for Cancer Research, National Cancer Institute, Frederick, MD, USA.
FEBS Lett. 2022 Dec;596(23):3060-3068. doi: 10.1002/1873-3468.14526. Epub 2022 Nov 7.
Bacterial L-asparaginases have been used for over 40 years as anticancer drugs. Ardalan et al. (Medical Hypotheses 112, 7-17, 2018) proposed that the V27T mutant of Escherichia coli type II L-asparaginase, EcAII(V27T), should display altered biophysical and catalytic properties compared to the wild-type enzyme, EcAII(wt), rendering it more favourable as a pharmaceutical. They postulated that EcAII(V27T) would exhibit reduced glutaminolytic activity and be more stable compared to EcAII(wt). Their postulates, however, were purely theoretical. Here, we characterized experimentally selected properties of EcAII(V27T). We found asparaginolytic activity of this mutant unchanged, whereas its glutaminolytic activity was fourfold lower compared with EcAII(wt). We did not observe significant differences in stabilities of EcAII(wt) and EcAII(V27T). Crystal structures of the complexes with L-Asp and L-Glu showed considerable differences in binding modes of both substrates.
细菌 L-天冬酰胺酶已被用作抗癌药物超过 40 年。Ardalan 等人（Medical Hypotheses 112, 7-17, 2018）提出，与野生型酶 EcAII（wt）相比，大肠杆菌 II 型 L-天冬酰胺酶的 V27T 突变体 EcAII（V27T）应显示出改变的生物物理和催化特性，使其更适合作为药物。他们推测 EcAII（V27T）将表现出降低的谷氨酰胺分解活性，并且比 EcAII（wt）更稳定。然而，他们的假设纯粹是理论上的。在这里，我们通过实验对 EcAII（V27T）的特性进行了表征。我们发现该突变体的天冬酰胺酶活性没有变化，而其谷氨酰胺分解活性比 EcAII（wt）低四倍。我们没有观察到 EcAII（wt）和 EcAII（V27T）稳定性的显著差异。与 L-Asp 和 L-Glu 形成复合物的晶体结构显示出两种底物结合模式的明显差异。
