PRODUCTION OF THE CHIMERIC-BINDING PROTEIN, MALTOSE-BINDING PROTEIN-PROTEIN-A, BY GENE FUSION

A fusion protein between maltose-binding protein (MBP) and staphylococ cal protein A (SpA) was genetically produced. The gene fusion plasmid, pMALPA2, was constructed by inserting the protein A gene into an expr ession vector of maltose-binding protein in frame, and was expressed e fficiently in Escherichia coli. The resulting fusion protein of molecu lar mass 65 kDa, retained the activity of both MBP and SpA (binding ca pability to amylose and immunoglobulin G). This chimeric-binding prote in was used as an adhesive molecule for immobilization of antibodies t o a solid-phase surface for enzyme immunoassay. An enzyme immunoassay was performed with the fusion protein, and human IgG was determined in the concentration range from 10(-4) to 10(-6) g ml(-1).