Biology Help please!

Question

For 60 years after the discovery of insulin by Banting and Best, insulin was extracted from beta cells of cattle or pigs to treat high blood sugar. Although the bovine insulin has 3 amino acids that were different from those of human insulin and the porcine insulin had one amino acid different, both gene products functioned very well in diabetic patients. If the insulin worked well in diabetic patients, why do you think scientists took the time to genetically engineer the molecule for the production in bacteria?

Answer 1

So that they can produce in large quantities at the fraction of the cost. Genetically engineered molecule can be grown in bacterial cells, they are easy to grow in laboratory conditions and would have very low mutation frequency when grown in control lab environment. Insulin can be isolated and purified  from these bacterial cultures at the minimal cost. Then it could be made available to many countries around the world where diabetes growing like an endemic, in particular many developing countries lack the facilities to produce insulin from bacterial cultures due to poor infrastructure.

 

Best, 

Answer 2

The major issue with insulin from pigs and cows is the risk of allergic reaction. The very first use of insulin in 1922 caused an allergic reaction in the patient. Over the years, as purification techniques have improved, the problem has decreased. Finally, with the development of insulin from E. coli, the problem has been almost eliminated, because insulin from bacteria has the exact same amino sequence as human insulin.

 

Some people do still experience a reaction to insulin injections, but mostly as a result of other things in the drug, like preservatives. The insulin itself rarely causes allergic reactions anymore.

 

As an additional benefit, the insulin from bacteria is cheaper to produce and more readily available, because bacteria reproduce a lot faster than cows/pigs.

 

Further reading: https://www.ncbi.nlm.nih.gov/pubmed/21496738