High-level expression of human alphaS1-casein in Escherichia coli

Abstract

Human αs1-casein was expressed efficiently in Escherichia coli. The overproduced recombinant human a αs1-casein was about 25% of the total cell protein. Two different vectors were constructed to express Met-αs1-casein and Met-αs1-casein with a His-affinity tag at the C-terminus. Recombinant Met-s1-casein with a His-affinity tag was purified to homogeneity using Ni-nitrilotriacetic acid resin. N-terminal sequence of the first 10 amino acid residues of this purified protein was identical to that of mature human αs1-casein with an extra methionine residue at the N-terminus.