Department of Biophysics, Faculty of Biological Sciences, Tarbiat Modares University, P.O. Box 14115-175, Tehran, Iran.
Department of Biochemistry, Faculty of Biological Sciences, Tarbiat Modares University, P.O. Box 14115-175, Tehran, Iran.
Int J Biol Macromol. 2021 Mar 1;172:162-169. doi: 10.1016/j.ijbiomac.2020.12.208. Epub 2021 Jan 5.
Considering importance and several industrial applications of lysozyme, including natural antibiotic and preservative, identifier for the diagnosis of diseases, and extraction purposes, its reversibility and stability studies can be very important. In this paper, the role that buffer and osmolytes concentrations play on the thermodynamic stability of lysozyme denaturation process, that is a new simple and inexpensive method, was evaluated by Nano-DSC III, far- and near-UV CD and fluorescence techniques. In thermal denaturation study, RI and ΔG of protein increased from 25.62% to 58.82% and 48.87 to 63.63 kJ mol with the increment of buffer and osmolytes concentrations, respectively. These changes showed a significant increase of 129.59% in RI and 28.16% in ΔG. The effect of buffer and osmolytes concentrations on the secondary and tertiary structures of protein was also investigated. The results indicated that increment of buffer and osmolytes concentrations increase rigidity and thermodynamic stability of protein. Also, structure of protein may be changed by its interaction with GNPs. Hence, interaction of lysozyme with GNPs was studied at the buffer and osmolytes concentrations that gives the maximum RI and ΔG, respectively. The results showed that molten globule-like state was formed by lysozyme in the presence of GNPs.
鉴于溶菌酶的重要性和多种工业应用，包括天然抗生素和防腐剂、疾病诊断的标志物以及提取目的，对其进行可逆性和稳定性研究可能非常重要。在本文中，通过 Nano-DSC III、远/近紫外 CD 和荧光技术评估了缓冲液和渗透剂浓度对溶菌酶变性过程热力学稳定性的影响，这是一种新的简单且廉价的方法。在热变性研究中，RI 和 ΔG 分别从 25.62%增加到 58.82%和从 48.87 增加到 63.63 kJ/mol，随着缓冲液和渗透剂浓度的增加。这些变化显示 RI 增加了 129.59%，ΔG 增加了 28.16%。还研究了缓冲液和渗透剂浓度对蛋白质二级和三级结构的影响。结果表明，缓冲液和渗透剂浓度的增加增加了蛋白质的刚性和热力学稳定性。此外，蛋白质的结构可能与其与 GNPs 的相互作用而改变。因此，在分别给出最大 RI 和 ΔG 的缓冲液和渗透剂浓度下研究了溶菌酶与 GNPs 的相互作用。结果表明，在 GNPs 的存在下，溶菌酶形成类似无规卷曲的状态。
