Protein passage efficiency

Because conditions are not constant during the batch concentration of the cell broth, protein transmission usually changes during the run. Thus transmission is not a consistent parameter for comparison of different rims. For purposes of summarizing protein transmission during the cell concentration step, a protein passage efficiency is used, which is defined as ... 

This is the weight fraction of enzyme in the feed actually recovered in the final permeate, normalized to the volume fraction of the feed collected as permeate. Unlike a simple yield calculation, this efficiency separates the effect of volume recovery from the effects of protein transmission. For example, for a five-fold volume reduction of the cell broth (before diafiltration), a protein passage efficiency of 100% corresponds to a yield of only 80%, because 20% of the protein originally fed is left behind in the retentate. For a constant passage efficiency, 3ueld will go up or down with changes in the volume reduction of the feed. For computational purposes, equation (3) reduces to a simple ratio of enz3une concentrations in the feed and final permeates ... 

Figure 6. Concentration of Cells (AG Techn. 500K MWCO Hollow Fibers) Summary of Protein Passage Efficiencies for 100 liter Scale Runs...

It has been reported that the plasmid vector is unable to translocate to the nucleus unless complexed in the cytoplasm with nuclear proteins possessing NLS. NLS are short karyophilic peptides on proteins that bind to specific transporter molecules in the cytoplasm, mediating their passage through the pore complexes to the nucleus. Examples of these peptides will be given later in this section. DNA can also be presented to cells in culture as a complex with polycations such as polylysine, or basic proteins such as protamine, total histones or specific histone fractions (110), cationized albumin, and others. These molecules increase the transfection efficiency. In addition histone HI is identified as transfection-enhancing protein in cell culture (111). 

This high molecular weight material could be effectively removed from the majority of the F-II by passage of the F-II through a 0.45 y durapore membrane with excellent recovery and efficient removal of high molecular weight proteins. These results are summarized in Scheme 6 and Figure 6. 

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