A β-Turn Rich Barley Seed Protein Is Correctly Folded in Escherichia coli

Wild-type and cysteine-containing mutant C hordeins from barley were expressed in Escherichia coli at high levels (≥ 30 mg/liter). N-terminal sequence analysis, SDS-PAGE, RP-HPLC, cd spectroscopy, and small angle X-ray scattering demonstrated that their physicochemical properties were similar to those of C hordeins isolated from barley grain. This indicates that the expressed proteins were correctly folded. The cysteine-containing mutant showed evidence of polymer formation in E. coli, nonreduced preparations of the protein showing the presence of polymers that were replaced by a single protein when a reducing agent was added.