Magnetic Silica Microspheres as a Novel Support for Immobilized Metal Affinity Purification of Proteins/Peptides

Magnetic silica microspheres with high magnetization and 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-glycidoxypropyltrimethoxysilane; and (iii) charging the magnetic support with Cu2+. The adsorption behavior of bovine serum albumin (BSA) as a model compound 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−1. These magnetic microbeads were further applied to the purification of 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 suitable for purification of histidine-tagged recombinant peptides or proteins.