Recombinant DNA process

Recombinant DNA processes can be used to make subunit vaccines. These can be classified either as biological or fermentation processes. Hepatitis B vaccines are made by genetic manipulation of yeast or animal cells. The cells then express the hepatitis B virus outer coat protein, which is harmless to the host because there is no DNA present. Similarly, in 2007, two companies launched a vaccine for cervival cancer caused by the human papilloma virus (HPV). 

The Federal investment in R D infrastructure outlined above made possible the fundamental knowledge and techniques upon which current drug discovery depends. The advances in molecular biology, which form the core of biotechnology (445), include recombinant DNA processes, monoclinal antibodies, and gene synthesis and splicing. Chapter 5 discusses the importance of these techniques in today s pharmaceutical R D process. These advances were made, for the most part, in university laboratories and relied heavily on Federal support. 

In many cases it is possible to synthesize the product of a gene in a different organism, eg, bacteria, yeast, or higher eukaryote. Recombinant DNAs directing the synthesis of the gene product must contain information specifying a number of biochemical processes. 

A fermentation route to 1-butanol based on carbon monoxide employing the anaerobic bacterium, Butyribacterium methjlotrophicum has been reported (14,15). In contrast to other commercial catalytic processes for converting synthesis gas to alcohols, the new process is insensitive to sulfur contaminants. Current productivities to butanol are 1 g/L, about 10% of that required for commercial viabiUty. Researchers hope to learn enough about the bacteria s control mechanisms to be able to use recombinant DNA to make the cells produce more butanol. 

It is often important to control the CSD of pharmaceutical compounds, eg, in the synthesis of human insulin, which is made by recombinant DNA techniques (1). The most favored size distribution is one that is monodisperse, ie, all crystals are of the same size, so that the rate at which the crystals dissolve and are taken up by the body is known and reproducible. Such uniformity can be achieved by screening or otherwise separating the desired size from a broader distribution or by devising a crystallization process that will produce insulin in the desired form. The latter of these options is preferable, and considerable effort has been expended in that regard. 

Human insulin is derived from a biosynthetic process using strains of Escherichia coli (recombinant DNA, rDNA). Human insulin appears to cause fewer allergic reactions than does insulin obtained from animal sources. Insulin analogy, insulin lispro, and insulin aspart are newer forms of human insulin made by using recombinant DNA technology and are structurally similar to human insulin. 

Experimental approaches that have afforded major insights to the processes described in this chapter include (1) use of yeast mutants (2) application of recombinant DNA techniques (eg, mutating or eliminating particular sequences in proteins, or fusing new sequences onto them and (3) development of in vitro... 

The above two processes employ isolated enzymes - penicillin G acylase and thermolysin, respectively - and the key to their success was an efficient production of the enzyme. In the past this was often an insurmountable obstacle to commercialization, but the advent of recombinant DNA technology has changed this situation dramatically. Using this workhorse of modern biotechnology most enzymes can be expressed in a suitable microbial host, which enables their efficient production. As with chemical catalysts another key to success often is the development of a suitable immobilization method, which allows for efficient recovery and recycling of the biocatalyst. 

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