Breakthrough curves of bovine immunoglobulin G (IgG) solutions from a recombinant protein G affinity membrane cartridge were significantly affected by flow velocity and feed solution concentration. Increasing the flow velocity decreased the amount of IgG bound to the membranes prior to breakthrough and broadened the breakthrough curve. Increased feed solution concentration allowed more IgG to bind prior to breakthrough but did not affect the shape of the curve. In batch incubation experiments, sorption of IgG to the membranes was slow, requiring 27 h to reach equilibrium. Sorption did not follow single-solute Langmuir kinetics. Desorption of IgG from the membranes during elution was flow rate dependent and produced multiple IgG peaks. These observations were interpreted using slow, competitive, and heterogeneous multisolute sorption of the IgG subclasses to the affinity membranes.

Protein sorption from raw rennet whey at pH 3.0 onto S-type (strong acid), and at pH 7.2 onto Q-type (strong base), ion exchange beads and membranes was measured. The data were used to analyze protein binding capacities, percentage recoveries, production rates, and design parameters for a commercial-scale process. Performance of S-type beads was superior to Q-type beads, but Q-type and S-type membranes performed comparably, except that the S-type membranes lost capacity during repeated cycling without cleaning, while the Q-type membranes did not. Performance of the S-type membranes was increased by microfiltration of the whey before loading, but this was partially offset by the lower protein content of the microfiltered whey. Increasing the flow rate through the cartridge increased productivity, but the percentage protein recovery decreased. This 1437