Department of Chemistry, KU Leuven, Celestijnenlaan 200F, 3001, Leuven, Belgium.
Chemistry. 2022 Feb 7;28(8):e202104224. doi: 10.1002/chem.202104224. Epub 2021 Dec 22.
Despite the enormous importance of insoluble proteins in biological processes, their structural investigation remains a challenging task. The development of artificial enzyme-like catalysts would greatly facilitate the elucidation of their structure since currently used enzymes in proteomics largely lose activity in the presence of surfactants, which are necessary to solubilize insoluble proteins. In this study, the hydrolysis of a fully insoluble protein by polyoxometalate complexes as artificial proteases in surfactant solutions is reported for the first time. The hydrolysis of zein as a model protein was investigated in the presence of Zr(IV) and Hf(IV) substituted Keggin-type polyoxometalates (POMs), (Et NH ) [M(α-PW O ) ] (M = Zr or Hf), and different concentrations of the anionic surfactant sodium dodecyl sulfate (SDS). Selective hydrolysis of the protein upon incubation with the catalyst was observed, and the results indicate that the hydrolytic selectivity and activity of the POM catalysts strongly depends on the concentration of surfactant. The molecular interactions between the POM catalyst and zein in the presence of SDS were explored using a combination of spectroscopic techniques which indicated competitive binding between POM and SDS towards the protein. Furthermore, the formation of micellar superstructures in ternary POM/surfactant/protein solutions has been confirmed by conductivity and Dynamic Light Scattering measurements.
尽管不溶性蛋白质在生物过程中具有极其重要的意义，但它们的结构研究仍然是一项具有挑战性的任务。人工酶样催化剂的开发将极大地促进它们结构的阐明，因为目前在蛋白质组学中使用的酶在存在表面活性剂时，其活性会大大降低，而表面活性剂是溶解不溶性蛋白质所必需的。在这项研究中，首次报道了多金属氧酸盐复合物在表面活性剂溶液中作为人工蛋白酶对完全不溶性蛋白质的水解。以玉米醇溶蛋白为模型蛋白，在Zr(IV)和Hf(IV)取代的 Keggin 型多金属氧酸盐（POM）（EtNH）[M(α-PW O )]（M = Zr 或 Hf）和不同浓度的阴离子表面活性剂十二烷基硫酸钠（SDS）存在下，研究了其水解。在与催化剂孵育时观察到蛋白质的选择性水解，结果表明 POM 催化剂的水解选择性和活性强烈依赖于表面活性剂的浓度。使用光谱技术组合研究了 SDS 存在下 POM 催化剂与玉米醇溶蛋白之间的分子相互作用，表明 POM 和 SDS 与蛋白质之间存在竞争结合。此外，通过电导率和动态光散射测量证实了三元 POM/表面活性剂/蛋白质溶液中胶束超结构的形成。
