Chemical synthesis of a gene for human cystatin C and its expression in E. coli

A DNA containing the coding sequence for the human cysteine proteinase inhibitor protein cystatin C has been obtained by enzymatic ligation of chemically synthesized deoxyoligonucleotides, using the Khorana ligation method. The 375 bp synthetic gene carries signals for the translation initiation and termination and was expressed in E. coli as a beta-galactosidase fusion protein as well as a secreted protein under the control of the E. coli alkaline phosphatase signal sequence. The secreted hybrid protein was shown to have similar biological properties as the authentic protein isolated from human plasma.