Benefits of Altered DNA
Part 1: Production of Insulin
As previously mentioned, there are many benefits of altering DNA by genetic engineering. Pharmaceutical companies producing human insulin (humalin) and human growth hormone (HGH) with bacteria with modified DNA were two of the earlier successes.
· Humalin: The introduction of genetically modified bacteria to produce human insulin replaced the use of cow and pig insulin. Although pig and cow insulin is very similar to human DNA, some people produce antibodies that reduce its effectiveness. Also, those who develop these antibodies tend to have inflammation at the point of injection. The introduction of humalin eliminated these complications.
![clip_image002[17]](http://www.alterdna.com/wp-content/uploads/2009/07/clip_image00217.jpg "Benefits of Altered DNA")
· HGH: HGH produced by the bacteria with modified DNA (called rHGH) replaced HGH extracted from cadavers (cadaver-GH). In 1985, there were four cases of Creutzfeldt-Jakob (mad cow) disease diagnosed in people who had been treated with cadaver-GH, leading to the eventual global ban. Genentech (USA) and Kabi (Swedish) had produced the first rHGH in 1981, leading to a sufficient supply when cadaver-GH was banned.
· Insulin Production: To produce insulin using bacteria, a process called recombinant DNA is used to
modify the DNA of the bacteria. The recombinant DNA process is a means of inserting new DNA into the existing DNA of an organism. For insulin production, the DNA is altered by inserting the insulin gene extracted from human DNA into a plasmid in the bacteria. A plasmid is a strand of DNA, usually circular, separate from a bacteria’s regular genome that replicates independently from the genome DNA. The insulin gene is inserted in the plasmid rather than the genome.
To prepare for purification of the modified bacteria, the gene that provides ampicillin tolerance is also inserted in a plasmid, along with the gene for luciferase, the protein that makes fireflies glow. The bacteria are then grown on a substrate containing ampicillin, so the surviving colonies that are ampicillin resistant glow in the dark are most likely to be the bacteria with the altered DNA. This method of selection is a purification step in the process.
Typically, the insulin is attached to the compound the bacteria normally excrete. In the final step an enzyme snips off the unwanted molecule and separates it from the desired compound.
The production of insulin using bacteria has been replaced by using genetically-engineered yeast. It was determined that it produces a form of insulin almost identical to human DNA. Neither the humalin from bacteria nor from yeast cause the side effects that animal insulin did.
Image Sources:
The Mummy (Boris Karloff ) as a cadaver:
Recombinant DNA Process:
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Read about Monoclonal Antibodies in our next installment.
