缢蛏(Sinonovacula constricta)重组Fe-铁蛋白和Mn-铁蛋白的性质解析

利用缢蛏(Sinonovacula constricta)重组铁蛋白富集Fe~(3+)和Mn~(2+)制备重组Fe-铁蛋白和Mn-铁蛋白,通过扫描电镜、X射线能量色散能谱仪(EDS)和MALDI TOF/TOF质谱系统测定蛋白的表面形貌变化、金属元素的能量变化和肽段分子量。利用综合物性测量系统(PPMS)测定蛋白纳米颗粒在室温300K,外加磁场3T下的磁学性质变化。结果显示,重组Fe-铁蛋白和Mn-铁蛋白与空白相比,表面形貌发生明显变化,Fe-铁蛋白仍为小球状,Mn-铁蛋白聚集体呈片层花球状,Cd-铁蛋白聚集体呈小圆球状,Mn-铁蛋白富集Cd~(2+)后呈片层花瓣散落状。Fe-铁蛋白和Mn-铁蛋白分别检测出相应金属元素且都有其特征能量态。两种重组蛋白的肽谱图与空白组相比,除铁蛋白保守肽段外还出现各自的特征肽段,推测与铁蛋白对Fe~(3+)和Mn~(2+)的富集功能密切相关。Fe-铁蛋白和Mn-铁蛋白纳米颗粒磁滞回线形状与铁蛋白空白组基本相同,呈顺磁性特征,磁性强度随Fe~(3+)和Mn~(2+)富集量的增加而增大。通过比较Fe-铁蛋白和Mn-铁蛋白与空白组在富集Hg~(2+)、As O43–和Cd~(2+)三种重金属离子方面能力的差异,发现Fe-铁蛋白对Hg~(2+)、AsO_4~(3–)和Cd~(2+)三种重金属的富集能力是空白组的2.4倍、1.7倍和3.7倍。Mn-铁蛋白对Hg~(2+)、AsO_4~(3–)和Cd~(2+)三种重金属离子在相同条件下的富集能力也有明显提高,分别为铁蛋白空白组的1.8倍、3.0倍和4.6倍。本研究结果为Fe-铁蛋白和Mn-铁蛋白在重金属污染治理方面的应用提供了数据参考。

RECOMBINANT FE-FERRITIN AND MN-FERRITIN FROM CHINESE RAZOR CLAM SINONOVACULA CONSTRICTA

The recombinant ferritin in Chinese razor clam Sinonovacula constricta were exposed to the same concentration of Fe³⁺ and Mn²⁺ to prepare for recombinant Fe-ferritin and Mn-ferritin. Scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and MALDI TOF/TOF mass spectrometry were applied to study changes in protein surface morphology, energy of metal elements, and molecular weight of peptides. The magnetic properties changes of protein nanoparticles were measured by physics property measurement system (PPMS) at room temperature (300K) and an external magnetic field (3T). The results indicate that compared with the ScFER, the surface topography of Fe-ferritin and Mn-ferritin changed obviously. Fe-ferritin remained globular, Mn-ferritin aggregates resembled lamellar flower, and Cd-ferritin aggregates were small round ball in shape, while Mn-ferritin that Cd²⁺-enriched formed lamella flower-like aggregate. Characteristic energy states of corresponding metal elements were detected from Fe-ferritin and Mn-ferritin. Compared with the ScFER, the peptides of the two recombinant proteins were distinct in addition to the conserved peptides of ferritin, suggesting that ferritin was closely related to the enrichment of Fe³⁺ and Mn²⁺. Fe-ferritin and Mn-ferritin nanoparticles had the same hysteresis loop as the blank group, showing paramagnetic characteristics, and the magnetic intensity increased with the increase of Fe³⁺ and Mn²⁺ contents. By comparing the ability of Fe-ferritin and Mn-ferritin in enriching heavy metals Hg²⁺, AsO₄^3- and Cd²⁺, we found that the ability of Fe-ferritin enrichment of Hg²⁺, AsO₄^3- and Cd² was 2.4, 1.7, and 3.7 times, and that of Mn-ferritin under the same conditions 1.8, 3.0, and 4.6 times higher of that of ScFER, respectively. These results provide a reference for the application of Fe-ferritin and Mn-ferritin in heavy metal pollution control.