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Layer-by-layer assembled magnetic bimetallic metal-organic framework composite for global phosphopeptide enrichment

Xiao, Ruili, Pan, Yini, Li, Jie, Zhang, Lingyi, Zhang, Weibing
Journal of chromatography 2019 v.1601 pp. 45-52
binding capacity, brain, chromatography, coordination compounds, magnetism, metal ions, moieties, phosphopeptides, proteomics, rats, skim milk, surface area
The highly selective enrichment of phosphopeptides is vital for the research of phosphorylated proteomics. Herein, a magnetic bimetallic metal-organic framework (MOF) with Zr-O and Ti-O clusters (denoted as Fe3O4@SiO2@(Zr-Ti-PTA)15) has been fabricated using a layer-by-layer assembly approach via the coordination of metal ions with carboxyl groups. The composite has large specific surface area (135.84 m2 g−1) and superparamagnetism (62.03 emu g−1). Compared with single-metal cluster MOF, the Fe3O4@SiO2@(Zr-Ti-PTA)15 showed higher binding capacity (100 mg g−1), enhanced affinity, better selectivity (nβ-casein : nBSA = 1 : 2000) and sensitivity (0.3 fmol/μL) towards phosphopeptides due to the combination of the dual metal clusters. Furthermore, the Fe3O4@SiO2@ (Zr-Ti-PTA)15 was successfully applied to extracting phosphopeptides from non-fat milk tryptic digest, and 10 mono-phosphopeptides and 22 multi-phosphopeptides were captured. As a result, 1294 phosphopeptides (476 multi-phosphopeptides and 818 mono-phosphopeptides) were selectively extracted and detected from tryptic digest of rat brain extract, indicating its great application potential in phosphorylated proteomics research.