Lesson 7 of 12 · 7 min
Genetically engineered insulin
NCERT §10.2, §10.2.1
Kavya's next week is in a hospital. Her first patient conversation is with a man in his sixties who has used insulin injections for twenty years.
The lesson in notes
In short
Recombinant DNA technology allows mass production of safe and more effective therapeutic drugs. Recombinant therapeutics do not provoke the unwanted immune responses common with similar products taken from non-human sources.
Worldwide, about 30 recombinant therapeutics have approval for use in humans; 12 of these are currently sold in India.
Adult-onset diabetes can be managed by taking insulin at regular intervals.
Insulin was earlier extracted from the pancreas of slaughtered cattle and pigs. Being a foreign protein, animal insulin caused allergy or other reactions in some patients.
Insulin is made of two short polypeptide chains, A and B, linked by disulphide bridges.
In mammals, humans included, insulin is made as a pro-hormone that must be processed before it works. The pro-hormone carries an extra stretch, the C peptide, which is removed during maturation and is absent from mature insulin.
The main difficulty in making insulin by rDNA techniques was getting it assembled into the mature form.
In 1983 the American company Eli Lilly made two DNA sequences, one for the A chain and one for the B chain of human insulin, and placed them in E. coli plasmids.
The A and B chains were produced separately, extracted, and joined by creating disulphide bonds, giving human insulin.