Comparison of bioseparation methods for microgravity experiments

The efficiency of the 1-g version of the continuous-flow electrophoresis (CFE) system flown on Space Shuttle missions is compared with the efficiency of a commercial CFE for separating living cells (human kidney, liver, and pituitary-gland cells and T-lymphocytes). In addition, the CFE system and a reciprocal isoelectric focusing (RIEF) system are compared with respect to protein pyrification efficiency. Correlations were made among electrophoretic mobilities (EPMs), secretory functions of cells, and input sample concentrations. A significant reduction in mean and range EPM was observed when input sample concentrations exceeded a low threshohold. This effect was not observed in microgravity experiments conducted at sample concentrations three times greater than the threshold for the controls. Comparison of CFE and RIEF methods showed that there are apparent advantages for each method depending on the product. For example, RIEF purification of urokinase removed more protein impurities, but focused the enzyme at a pH different than the enzyme's known isoelectric point.