Abstract
The purpose of this study is to evaluate the effect of operating conditions upon the separation of endonuclease DNase I on micron-size aqueous polymer two-phase systems. The end product DNaseI is a clinically useful enzyme used for cystic fibrosis. First, to achieve extracellular production of DNaseI, genetically modified strain of Pichia pastoris was constructed. Second, a method to separate DNaseI from culture supernatant was investigated using continuous laminar two-phase flow of aqueous polymers on microchannel device (500µm width, 300µm depth). Solutions of aqueous polymers were polyethylene glycol (PEG) and Dextran (Dex). The PEG solution containing DNaseI and the Dex solution without DNaseI were introduced separately into the device using micro syringe pumps and contacted in microchannel. DNaseI was partitioned from PEG phase to Dex phase. Concentrations of DNase I in PEG phase and in Dextran phase were determined by using absorption measurement method. The effects of space-time on the concentrations of DNase I in both polymer phases at the exit were investigated. On the basis of experimental data, mass transfer coefficient of DNase I from PEG phase to Dex phase was evaluated. Simulation of DNaseI-extraction was also performed. Micron-size two-phase system was found to promise a rapid transport of DNase I in separation by reason of its high specific surface area.
