In this study, a facile synthesis of the titanium(IV) ion-immobilized poly-glycidyl methacrylate microparticles functionalized with polyethylenimine and adenosine triphosphate was developed for efficient enrichment of intact phosphoproteins. The titanium(IV) ion-immobilized microparticles had higher saturated adsorption capacity for phosphoproteins (1217.6 mg/g for β-casein) than nonphosphoproteins (97.1 mg/g for bovine serum albumin) and the average particle diameter was about 1.4 μm with good dispersibility. In application, as demonstrated by SDS-PAGE, titanium(IV) ion-immobilized microparticles exhibited good performance in enriching intact phosphoproteins from standard protein mixtures of β-casein and bovine serum albumin with high specificity and selectivity. In addition, titanium(IV) ion-immobilized microparticles were also successfully applied in intact phosphoprotein enrichment from complex biological samples including nonfat milk, chicken egg white, and mouse heart tissue extract.
Keywords: enrichment; immobilized titanium(IV) affinity chromatography; intact phosphoproteins.
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