Malihe Moghadam1, Ali Ganji1, Abdolreza Varasteh2, Reza Falak3, Mojtaba Sankian1. 1. Immunology Research Center, Medical School, Mashhad University of Medical Sciences, Mashhad, Iran. 2. Allergy Research Center, Medical School, Mashhad University of Medical Sciences, Mashhad, Iran. 3. Immunology Research Center, Iran University of Medical Sciences, Tehran, Iran; Department of Immunology, Iran University of Medical Sciences, Tehran, Iran.
Abstract
BACKGROUND: Recombinant proteins overexpressed in E. coli are usually deposited in inclusion bodies. Cysteines in the protein contribute to this process. Inter- and intra- molecular disulfide bonds in chitinase, a cysteine-rich protein, cause aggregation when the recombinant protein is overexpressed in E. coli. Hence, aggregated proteins should be solubilized and allowed to refold to obtain native- or correctly- folded recombinant proteins. METHODS: Dilution method that allows refolding of recombinant proteins, especially at high protein concentrations, is to slowly add the soluble protein to refolding buffer. For this purpose: first, the inclusion bodies containing insoluble proteins were purified; second, the aggregated proteins were solubilized; finally, the soluble proteins were refolded using glutathione redox system, guanidinium chloride, dithiothreitol, sucrose, and glycerol, simultaneously. RESULTS: After protein solubilization and refolding, SDS-PAGE showed a 32 kDa band that was recognized by an anti-chitin antibody on western blots. CONCLUSIONS: By this method, cysteine-rich proteins from E. coli inclusion bodies can be solubilized and correctly folded into active proteins.
BACKGROUND: Recombinant proteins overexpressed in E. coli are usually deposited in inclusion bodies. Cysteines in the protein contribute to this process. Inter- and intra- molecular disulfide bonds in chitinase, a cysteine-rich protein, cause aggregation when the recombinant protein is overexpressed in E. coli. Hence, aggregated proteins should be solubilized and allowed to refold to obtain native- or correctly- folded recombinant proteins. METHODS: Dilution method that allows refolding of recombinant proteins, especially at high protein concentrations, is to slowly add the soluble protein to refolding buffer. For this purpose: first, the inclusion bodies containing insoluble proteins were purified; second, the aggregated proteins were solubilized; finally, the soluble proteins were refolded using glutathione redox system, guanidinium chloride, dithiothreitol, sucrose, and glycerol, simultaneously. RESULTS: After protein solubilization and refolding, SDS-PAGE showed a 32 kDa band that was recognized by an anti-chitin antibody on western blots. CONCLUSIONS: By this method, cysteine-rich proteins from E. coli inclusion bodies can be solubilized and correctly folded into active proteins.
Entities:
Keywords:
Chitinase; Cysteine-rich proteins; Protein refolding; Protein solubilization
Authors: Ayokunmi Omolola Oyeleye; Siti Faridah Mohd Yusoff; Izzah Nadiah Abd Rahim; Adam Thean Chor Leow; Noor Baity Saidi; Yahaya M Normi Journal: PLoS One Date: 2020-10-22 Impact factor: 3.240