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Updated: Jul 5, 2026

Identification of Protein Interacting Partners Using Tandem Affinity Purification
Published on: February 25, 2012
Strategy for purifying maltose binding protein fusion proteins by affinity precipitation
Smita Raghava1, Samina Aquil, Sanchari Bhattacharyya
1Chemistry Department, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India.
Abstract:
The maltose binding protein (MBP) affinity tag has been extensively used for protein purification. A commercial grade cationic starch could precipitate MBP or an MBP-tagged protein quantitatively by simultaneous addition of 10% (w/v) polyethylene glycol (PEG) and 50 mM calcium chloride. The precipitated MBP or MBP-tagged protein could be selectively dissociated by suspending the precipitate in 1 M NaCl. In the case of a soluble MBP fusion with a fragment of human immunodeficiency virus protein gp120, 38% of the contaminating proteins could be removed by precipitation with PEG/CaCl(2) and 100% of the fusion protein was recovered. In all cases, the purified proteins showed a single band on sodium dodecyl sulfate-polyacrylamide gel electrophoresis and the expected changes in fluorescence emission spectra upon binding to maltose.
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