Large-scale Transient Expression

Wurm FM, Bernard A (1999), Large-scale transient expression in mammalian cells for recombinant protein production, Curr. Opin. Biotech. 10 156-159. 

Blasey HD,AubryJ-P,Mazzei GJ,Bernard AR (1996) Large scale transient expression with COS cells. Cytotechnology 18 183-192... 

In the next contribution we learn about hands-on experience and recent improvements with different production systems for biopharmaceuticals at Bayer Health-Care. As previously also published in Nature by Heiner Apeler, Head of Expression, an E. coli host/vector system was originally developed for the efficient production of an interleukin-4 variant, but afterwards it was optimized for the expression of other proteins and even Fab fragments. Process development and optimization of the yeast secretory Saccharomyces cerevisiae for expression of a protease inhibitor will also be presented. The focus, however, is on the use of a recently developed mammalian HKBll (hybrid clone of human kidney and B cells) expression system for recombinant human glycoprotein biopharmaceuticals. HKBll is a favorable cell host for the production of human proteins, because it dehvers biopharmaceuticals that are structurally identical to the natural product. The host/vector system supports the production of gram quantities of proteins in a large-scale transient transfection format as well as the development of stable cell fines. These systems together... 

Baldi, L., Muller, N., Picasso, S., Jacquet, R., Girard, P., Thanh, H. R, et al. (2005). Transient gene expression in suspension HEK-293 cells application to large-scale protein production. Biotechnol. Prog. 21,148-153. 

Another approach towards inhibition of silencing is to block deacetylation of histones. Acetylated histones are considered the primary hallmark of active chromatin [61]. In recent investigations by Hacker and colleagues, it was shown that increased expression from silenced transgenes in recombinant CHO cell Hnes could be mediated by transient expression of Gam-1, an avian adenovims protein that is known to block deacetylase activity [62]. It should be mentioned in this context that the successful appHcation of butyrate in large-scale manufacturing processes for... 

Literature on thermodynamics of biopolymers other than proteins, such as DNA, does not seem to be available in large amounts. It is conceivable that this area might become important due to the fact that the scale at which DNA will have to be isolated and purified will become considerably larger in the future, as such areas as somatic gene therapy, DNA immunization and vaccination, and transient expression of gene products for rapid production of preparative amounts of recombinant proteins gain wider interest [28-31]. 

Fast transient studies are largely focused on elementary kinetic processes in atoms and molecules, i.e., on unimolecular and bimolecular reactions with first and second order kinetics, respectively (although confonnational heterogeneity in macromolecules may lead to the observation of more complicated unimolecular kinetics). Examples of fast thennally activated unimolecular processes include dissociation reactions in molecules as simple as diatomics, and isomerization and tautomerization reactions in polyatomic molecules. A very rough estimate of the minimum time scale required for an elementary unimolecular reaction may be obtained from the Arrhenius expression for the reaction rate constant, k = A. The quantity /cg T//i from transition state theory provides... 

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