Purification and partial characterization of the cold shock protein CspC from Escherichia coli

After two-step chromatography of Sepharose Q Fast Flow and Superdex 30, a small protein with molecular size of 7.2 ku was purified from Escherichia coli. The purity examined by SDS-PAGE showed as a single band. Its molecular mass measured by mass spectrum and the amino acid sequence of N terminal were in consistence with CspC, one of the cold shock proteins, in E. coli. Subsequently, the content of its secondary structure was estimated from the circular dichroism spectra, and moreover, its stability in high temperature and the conformational change after binding with single strand DNA were monitored with a CD spectrophometer.