β-Amyloid Peptide 1–42-Conjugated Magnetic Nanoparticles for the Isolation and Purification of Glycoproteins in Egg White

Abstract

Aβ 1−42 -conjugated magnetic nanoparticles, Aβ 1−42 @MNP, were prepared by covalently coupling Aβ 1−42 to hyperbranched polyethyleneimine (PEI)-modified magnetic nanoparticles via N-(3dimethylaminopropyl)-N′-ethylcarbodiimide hydrochloride (EDC). Aβ 1−42 's high binding capacity to glycosyl groups facilitates Aβ 1−42 @ MNP composite to be a promising selective adsorbent for glycoproteins in egg whites. In our study, under conditions of pH 4.0, the adsorption efficiency of Aβ 1−42 @MNP composite for ovalbumin (100 μg mL −1 ) was 98.4% and its maximum adsorption capacity was 344.8 mg g −1 ; under the condition of pH 4.0 and 200 mmol L −1 NaCl, its adsorption efficiencies for ovalbumin and ovotransferrin were 96.9% and 60.0%, respectively. According to these primary data, in practice, ovalbumin was removed from egg white by Aβ 1−42 @MNP composite at pH 4.0 (step I), and then after adding NaCl until the final salt concentration reached 200 mmol L −1 (pretreated egg white), we utilized the same adsorbent to further isolate/purify glycoproteins (step II). SDS-PAGE results showed that Aβ 1−42 @MNP composite could largely remove ovalbumin in step I and could isolate/purify the remaining ovalbumin and ovotransferrin in step II. LC−MS/MS analysis results showed that the removal of ovalbumin reduced its percentage in egg white samples from 32.93% to 11.05% in step I and the remaining ovalbumin and ovotransferrin were enriched in step II, where the final percentage reached 11.6% and 12.6%, respectively. In summary, 81 protein species were identified after two-step extraction with Aβ 1−42 @MNP on egg white, while only 46 protein species were identified directly from raw egg white without any pretreatment. This work well illustrates the excellent adsorption performance of Aβ 1−42 @MNP composite to glycoproteins and its potential in the application of proteomic studies on low-abundance proteins in egg white.

Iron Oxide Nanomaterials at Interfaces for Sustainable Environmental Applications

“…Protein extraction and characterization is a quite cumbersome process because it involves selective centrifugation in a stepwise manner to extract different protein fractions. Water soluble hybrid magnetic NPs can perform this extraction elegantly by complexing and extracting different protein fractions. , A load of protein fractions adsorbed on metal–magnetic hybrid NPs act as vehicles for protein extraction simply by using the external magnetic field and without implementing laborious centrifugation techniques (Figure A) . Protein fractions are dislodged from the surface of NPs and then characterized through SDS page electrophoresis.…”