Xu Xiafan, Du Chunlan, Ren Zilong, Zhang Min, Ma Lin
School of Chemistry and Chemical Engineering, Guangxi University, Nanning 530004, PR China.
ACS Omega. 2021 Apr 14;6(16):10859-10865. doi: 10.1021/acsomega.1c00562. eCollection 2021 Apr 27.
For a better understanding on the interaction between polyethyleneimine (PEI) and proteins, spectroscopic studies including UV-vis absorption, resonance Rayleigh scattering, fluorescence, and circular dichroism were conducted to reveal the conformational change of rabbit muscle lactate dehydrogenase (rmLDH) and related to the bioactivity of the enzyme. Regardless of the electrostatic repulsion, PEI could bind on the surface of rmLDH, a basic protein, via hydrogen binding of the dense amine groups and hydrophobic interaction of methyl groups. The competitive binding by PEI led to a reduction of the binding efficiency of rmLDH toward β-nicotinamide adenine dinucleotide, the coenzyme, and sodium pyruvate, the substrate. However, the complex formation with PEI induced a less ordered conformation and an enhanced surface hydrophobicity of rmLDH, facilitating the turnover of the enzyme and generally resulting in an increased activity. PEI of higher molecular weight was more efficient to induce alteration in the conformation and catalytic activity of the enzyme.
为了更好地理解聚乙烯亚胺（PEI）与蛋白质之间的相互作用，进行了包括紫外可见吸收、共振瑞利散射、荧光和圆二色性在内的光谱研究，以揭示兔肌肉乳酸脱氢酶（rmLDH）的构象变化及其与酶生物活性的关系。尽管存在静电排斥，PEI仍可通过密集胺基的氢键作用和甲基的疏水相互作用，结合在碱性蛋白质rmLDH的表面。PEI的竞争性结合导致rmLDH对辅酶β-烟酰胺腺嘌呤二核苷酸和底物丙酮酸钠的结合效率降低。然而，与PEI形成复合物会诱导rmLDH形成较无序的构象并增强其表面疏水性，促进酶的周转并通常导致活性增加。较高分子量的PEI在诱导酶的构象和催化活性改变方面更有效。
