Recombinant DNA Technology For Insulin Production

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Genetically Engineered Insulin

Insulin is a hormone which is produced in pancreas by beta cells. Insulin is released every 3 to 6 minutes from the pancreas. Human insulin protein consists of 110 amino acids and has a molecular mass of 5808 Da. Insulin consists to two short polypeptide chains - Chain A (21 amino acids) and Chain B (30 amino acids), that are linked together by two disulphide bridges.

Effect of insulin on glucose uptake and metabolism. 

Insulin binds to its receptor, which in turn starts many protein activation cascased. These include: translocation of Glut-4 transporter to the plasma membrane and influx of glucose, glucogen synthesis, glycolysis and fatty acid synthesis. It works at other sizes, but sometimes truncates the text on the far right.

Diabetes and Insulin

Insulin regulates sugar metabolism and insufficiency or lack of insulin leads to high blood sugar level; this disease is called diabetes.
Injecting insulin at regular intervals manages the adult-onset diabetes.

The injected insulin, earlier, were extracted from pancreas of slaughtered cattle or pigs.

However, some patients developed allergy and other immunological reactions to the animal protein.

Along the Insulin production path, there is very extensive modifications which insulin undergoes after translation. The production of insulin is more or less independent of the secretion oscillations. So the insulin is produced by the pancreas and is stored till the next secretion cycle. The insulin path includes:
  1. translation and translocation,
  2. folding, oxidation and signal peptide cleavage,
  3. ER export, Golgi transport, vesicle packaging,
  4. protease cleavage liberates C-peptide and
  5. carboxypeptidase E produces mature insulin

Recombinant DNA Technology (rDNA)

Recombinant DNA Technology (rDNA) technology has enabled to mass produce safe and more effective therapeutic drugs.

Also they do not induce unwanted immunological responses, common to the product isolated from non-human sources.

There are about 30 recombinant therapeutics approved for human use. In mammals, including humans, insulin is synthesised as a pro-hormone, which contains an extra stretch called C peptide.

Like a pro-enzyme, the pro-hormone also needs to be processed before it becomes fully mature and a functional hormone.

The C Peptide is not present in the mature insulin and is removed during maturing.

The main challenge for production of insulin using rDNA technology was getting insulin assembled into a mature form.

On 5th July, 1983, Eli Lilly, an American Company, prepared two DNA sequences corresponding to chains A and B and introduced them into plasmids of E.coli to produce insulin chain - humulin (human insulin).
Chains A and B were produced separately, extracted and combined by creating disulphide bonds to form human insulin.

Multiple Choice Questions on Insulin

Insulin is a dimer of an A-chain and a B-chain, which are linked together by _______ bond
(1) hydrogen
(2) phosphodiester
(3) glycosidic
(4) disulphide
Ans:   Click here

Insulin belong to the category of
(1) Steroids
(2) Vaccines
(3) Antibiotics
(4) Hormones
Ans:   Click here

On 5th July, 1983, _________, an American Company, prepared two DNA sequences corresponding to chains A and B and introduced them into plasmids of E.coli to produce insulin chain - humulin (human insulin).
(1) Merck
(2) Abbott Laboratories
(3) Pfizer
(4) Eli Lilly
Ans:   Click here

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