College of Chemistry and Chemical Engineering, Shanxi University, Taiyuan, Shanxi 030006, China.
College of Chemistry and Chemical Engineering, Shanxi University, Taiyuan, Shanxi 030006, China.
Int J Biol Macromol. 2018 Oct 15;118(Pt A):244-251. doi: 10.1016/j.ijbiomac.2018.06.051. Epub 2018 Jun 18.
The interaction between surfactin and alkaline protease in aqueous solution has been studied. Ultraviolet visible absorption spectra (UV-vis) show that surfactin causes the extension of peptide chain of the alkaline protease resulting in the weakening of hydrophobic interaction between the hydrophobic groups. Fluorescence spectra indicate that the interaction of surfactin with the tryptophan and tyrosine residues led to a change of conformation of the alkaline protease. Fourier transform infrared spectroscopy (FTIR) proves complex weak interactions between surfactin and alkaline protease, especially hydrogen bonds. Enzyme activity measurements demonstrate that low concentration of surfactin can increase the enzyme activity of alkaline protease, while high concentrations inhibit it. The particle size and Zeta potential measurements confirm that the system particle size and Zeta potential are dependent on the concentration of surfactin, in addition, there is the electrostatic interaction between surfactin and alkaline protease. Surface tension measurements indicate that the binds of surfactin and alkaline protease molecules are spontaneous. Based on experimental results, the composite model of surfactin and alkaline protease in aqueous solution is proposed.
已研究了表面活性剂与水溶液中碱性蛋白酶之间的相互作用。紫外可见吸收光谱（UV-vis）表明，表面活性剂导致碱性蛋白酶的肽链伸展，从而削弱了疏水区之间的疏水相互作用。荧光光谱表明，表面活性剂与色氨酸和酪氨酸残基的相互作用导致碱性蛋白酶构象发生变化。傅里叶变换红外光谱（FTIR）证明了表面活性剂与碱性蛋白酶之间存在复杂的弱相互作用，特别是氢键。酶活性测定表明，低浓度的表面活性剂可以提高碱性蛋白酶的酶活性，而高浓度则抑制其活性。粒径和 Zeta 电位测量证实，该体系的粒径和 Zeta 电位取决于表面活性剂的浓度，此外，表面活性剂和碱性蛋白酶之间还存在静电相互作用。表面张力测量表明，表面活性剂和碱性蛋白酶分子的结合是自发的。基于实验结果，提出了表面活性剂与碱性蛋白酶在水溶液中的复合模型。
