An improved method for refolding recombinant decay accelerating factor for therapeutic studies

Decay accelerating factor (DAF) is a very potent complement regulatory protein which holds promise for clinical usage. Here we report on an improved procedure for refolding both rat and human DAF over-expressed in Escherichia coli. It was shown that 50–70% of the inclusion body could be refolded to soluble active protein. This method excludes the use of l-arginine, which is expensive, and can be used to prepare a large quantity of recombinant DAF for therapeutic studies.