C.T. Lee and A.P.J. Middelberg*<=
/sup>
Department of Che=
mical
Engineering, University of Cambridge, UK
We demonstrate that an oscillatory flow-mixing reactor (OFMR) operating in fed-batch mode is viable for industrial protein refolding. OFMR offers the advantage of uniform, controllable, and scalable mixing. Denatured lysozyme (15 mg/ml, in = 8 M guanidine hydrochloride (GuHCl) or 8 M urea, and 32 mM dithiothreitol) was = fed into a 150-ml OFMR for 2 h and the final solution was incubated for a furth= er 3 h. A control experiment used= a small perfectly-mixed stirred-tank reactor (STR). Both systems were operated under mild and intense mixing conditions. With GuHCl denaturation, the refolding yield profiles throughout the 5 h period were identical in both the OFMR and STR, and yield was independent of mixing intensity. Conversely, refol= ding yield in both reactors following urea denaturation decreased from 25% to 15= % as mixing intensity decreased. Clearly, imperfect mixing in large STRs may lead to reduced refolding yield when urea is used as a denaturant.&= nbsp; This effect can be minimised by using a reactor with uniform, controllable and scaleable mixing, such as the OFMR.