Using a bioinformatical approach, a hybrid gene encoding the Fc-binding domains of both SPA and SPG (1 269 bp) was designed and synthesized. The sequence was designed by substitution of high-usage codons for low-usage ones of Escherichia coli. A total of 64 oligonucleotides were assembled in a single-step, in which T4 DNA ligase ligated DNA fragments from a pool of overlapping oligonucleotides. The synthetic gene was cloned to pSK vector. After sequencing and remending, the gene was expressed using the expression vector pET-28a-c(+). A band of 47 ku was detected with Western blot analysis. The protein so called MproteinAG has been covalently conjugated to the carboxyl-terminated magnetic particles. With the MproteinAG magnetic particles,IgG from blood serium of rabbit, pig,dog,mouse, human, macaque, rat, cat, sheep, cattle, horse can be purificated in one hour.