Magnetic silica microspheres as a novel support for immobilized metal affinity purification of proteins/peptides

Magnetic silica microbeads with high magnetization, uniform particle size distribution were modified by silane coupling agents to yield a novel support for immobilized metal affinity purification of proteins. The synthetic procedure consists of three steps: (i) the preparation of magnetic silica microbeads by polymer templating method; (ii) coupling of iminodiacetic acid (IDA) with a bifunctional silane agent 3-glycidoxypropyl trimethoxysilane; (iii) charging the magnetic support with Cu2+. With bovine serum albumin (BSA) as a model compound, the adsorption behavior of protein on the magnetic matrix was studied. Preliminary results show that the adsorption of BSA can be described by Langmuir equation with saturation capacity being 90 mg/g. These magnetic microbeads were further applied to purify a recombinant peptide Analgesic-antitumor peptide (AGAP), directly from cell lysis without sample pretreatment. Being simple and specific, the magnetic silica microbeads based protocol is especially suited for purification of histidine-tagged recombinant peptides or proteins.