Proteins recombinant DNA

Quick cooling is often advantageous, e. g. for recombinant DNA-proteins, in order to avoid crystallization of salts and to obtain the best possible, homogeneous cake. 

Figure 3.1 shows the influence of different freezing methods on the activity of a recombinant DNA protein. However, in the case of other macromolecules, for example a monoclonal antibody, there may be exceptions from the rule and different factors (e. g. pH-value) play an important role. 

Fig. 3.1. Influence of different freezing processes on the activity of recombinant DNA protein.

The problem of the immunogenic nature of many human recombinant DNA proteins, and the potential to generate antibodies to a normal human protein, is of special interest to the immunotoxicologist. For example, 3 of 16 patients administered the rDNA-derived interferon-a (clone A) developed antibodies of the IgG class that were undetectable prior to or during therapy (Gutterman et al., 1982). These antibodies were capable of in vitro neutralization of interferon activity, although in vivo neutralization of interferon has not been documented. Since there are several different subtypes of interferon-a s, some contain epitopes not present on their own interferon subtype. Similarly, two patients treated with interferon-/ for many months developed high-titered antibody, which in one case was correlated with an inability of the patient s fibroblasts to produce interferon (Vallbracht et al., 1982). 

Fig. 3.1. Influence of different freezing processes on the activity of recombinant DNA protein. A, Solution before freezing B, freeze-dried after quick freezing C, freeze-dried after freezing on precooled shelves D, freeze-dried after cooling shelves and product simultaneously (Figure 1 from [3.6])...

S6 outlines the products for which this guidance is applicable, such as recombinant DNA proteins, vaccines, peptides, plasma derived products, endogenous proteins extracted from human tissues or oligonucleotide drugs etc., while heparin, vitamins, and cellular blood components, for example, are not covered. 

For a recombinant DNA protein, expression system comparison with the native sequence. 

In general recombination, the exchange of DNA sequences takes place between homologous sequences. In site-specific recombination, DNA-protein interactions are principally responsible for the exchange of nonhomologous sequences. 

Morris, H. R., M. Panico, and G. W. Taylor FAB-Mapping of Recombinant-DNA Protein Products. Biochem. Biophys. Res. Comm. 117, 299 (1983). 

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