[Purification and properties of human lysozyme in engineered bacterium E. coli]

To obtain the SDS-PAGE-pure human lysozyme, the crude enzyme of engineered bacterium E. coli was purified by chromatography on cation ion exchange of Express-Ion S. The optimum reaction temperature and pH of this lysozyme were 45 degrees C and 6.5, respectively. The isoelectric point is pH 8.91, and Km of the enzyme for Micrococcus lysodeikticus is 0.0311 mg/mL. The thermal stability of the engineered enzyme is more sensible than hen egg white lysozyme and human milk lysozyme. The sequence of 5 amino acids in N-end is same as designed, except an Met at the first. The affects of some metal ion on this enzyme were shown. Cu2+ of 0.01 mmol/L could completely inactivate the enzyme.