Genetic engineering enhanced cell activity

G. Genetic Engineering for Broadly Enhanced Cell Activity... 

Physiological optimization of enzyme synthesis by variation of the culture parameters is usually required to enhance the catalytic activity of whole-cell biocatalysts to such a level that it can be apphed in a biocatalytic process. In addition, physiological conditions can influence the selectivity of the reaction, since enzymes with opposite selectivities can be differentially expressed. In some cases, genetic engineering is required to obtain biocatalysts with a desired selectivity that does not consume the product of choice (see 5.3.5). Alternatively, one may choose to isolate the desired activity from the culture in order to use the biocatalyst in an enzyme reactor. 

The enhanced availability of receptors, enzymes and cell systems has permitted these entities to be considered as viable means for the evaluation of very small amounts of a sample on an automated basis. This, in turn, has led to another important change, namely the rate at which new biologically active entities can be discovered. Whereas it previously took weeks or months to test a few hundred samples, it now takes, for some assays, only a matter of hours. Whole cell, enzyme-based, and receptor-based assays are now quite routine in many therapeutic target areas, and the emphasis is shifting rapidly to genetically-engineered assays which evaluate the ability of a compound to interfere with a biological process in an exceptionally specific manner. 

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