Aricov Ludmila, Precupas Aurica, Tudose Madalina, Baltag Dragos, Trică Bogdan, Sandu Romica, Leonties Anca Ruxandra
"Ilie Murgulescu" Institute of Physical Chemistry, Romanian Academy, Spl. Independentei 202, 060021, Bucharest, Romania.
"Ilie Murgulescu" Institute of Physical Chemistry, Romanian Academy, Spl. Independentei 202, 060021, Bucharest, Romania.
Environ Res. 2023 Nov 15;237(Pt 1):116920. doi: 10.1016/j.envres.2023.116920. Epub 2023 Aug 18.
In this study, the impact of gold nanoparticles (AuNPs) on the structure and activity of laccase from Trametes versicolor (Lc) was described. Fluorescence experiments revealed that AuNPs efficiently quench Lc's tryptophan fluorescence by a static and dynamic process. By using differential scanning microcalorimetry and circular dichroism spectroscopy, it was determined how the concentration of nanoparticles and the composition of the medium affected the secondary structure of Lc. The data revealed that upon binding with AuNPs, conformational changes take place mainly in presence of high amounts of nanoparticles. The complex kinetic analysis unveiled the Lc activity enhancement at low concentrations of AuNPs as opposed to the concentrated regime, where it can be reduced by up to 55%. The Michaelis-Menten tests highlighted that the activity of the biocatalyst is closely related to the concentration of AuNPs, while the Selwyn analysis demonstrated that even in a concentrated regime of Lc it is not deactivated regardless of the amount of AuNPs added. The thermal parameters improved by twofold in the presence of low AuNPs concentration, whereas the activation energy increased with AuNPs content, implying that not all collisions are beneficial to the enzyme structure. The effect of AuNPs on the decomposition of a recalcitrant dye (naphthol green B, NG) by Lc was also evaluated, and the Michaelis-Menten model revealed that only the high AuNPs content influenced negatively the Lc activity. The isothermal titration calorimetry revealed that hydrogen bonds are the main intermolecular forces between Lc and AuNPs, while electrostatic interactions are responsible for NG adsorption to AuNPs. The results of the docking analysis show the binding of NG near the copper T1 site of Lc with hydrogen bonds, electrostatic and hydrophobic interactions. The findings of this work provide important knowledge for laccase-based bio-nanoconjugates and their use in the field of environmental remediation.
在本研究中，描述了金纳米颗粒（AuNPs）对云芝漆酶（Lc）结构和活性的影响。荧光实验表明，AuNPs通过静态和动态过程有效地猝灭了Lc的色氨酸荧光。通过差示扫描量热法和圆二色光谱法，确定了纳米颗粒浓度和介质组成如何影响Lc的二级结构。数据表明，与AuNPs结合时，构象变化主要发生在大量纳米颗粒存在的情况下。复杂动力学分析表明，与高浓度情况相反，低浓度AuNPs时Lc活性增强，在高浓度时活性可降低高达55%。米氏试验强调，生物催化剂的活性与AuNPs浓度密切相关，而塞尔温分析表明，即使在Lc的高浓度体系中，无论添加多少AuNPs，它都不会失活。在低AuNPs浓度存在下，热参数提高了两倍，而活化能随AuNPs含量增加，这意味着并非所有碰撞都对酶结构有益。还评估了AuNPs对Lc分解难降解染料（萘酚绿B，NG）的影响，米氏模型表明只有高AuNPs含量对Lc活性有负面影响。等温滴定量热法表明，氢键是Lc与AuNPs之间的主要分子间作用力，而静电相互作用是NG吸附到AuNPs的原因。对接分析结果表明，NG通过氢键、静电和疏水相互作用与Lc的铜T1位点附近结合。这项工作的发现为基于漆酶的生物纳米缀合物及其在环境修复领域的应用提供了重要知识。
