Question

NATIONAL CENTER FOR CASE STUDY TEACHING IN SCIENCE Part lIl Chemical Synthesis of Human Insulin - Close, but no Cigar In order to meet the increasing demands for insulin, and to eliminate the adverse side effects of animal insulin, scientists began searching for ways to synthesize human insulin in the hrSr lab. The first attempts to produce synthetic human insulin 2 3 459101112 13 14151617 1819 20 21 made use of chemical reactions to join amino acids in the correct order to make the insulin protein. Before scientists could do this, however, they needed to know the primary Chain B amino acid sequence of insulin ain Phe val Asn Gn H GlyeHi alGu laTy ays Gly The amino acid sequence of human insulin was worked out23 4 5678 9 10 11 12 13 14 15 16 17 18 19 20 by Frederick Sanger in 1951 insulin was in fact the first protein to be sequenced), and he was awarded the Nobel Prize in 1958 for his discovery. Insulin is composed of two short chains, the A chain and the B chain, which are held together by disulfide bonds or bridges between cysteine Figure 2. Amino acid sequence of human insulin. Each amino acid amino acids present in the two chains Glu 21 30 29 28 27 26 25 24 23 22 is represented by a circle. Disulfide bonds are shown by lines Human insulin was chemically synthesized in the early 1960s by several academic groups, including those at the University of Pittsburgh and Aachen University in Germany. To do this, the scientists produced the A and B chains separately by joining the amino acids in the correct order through a series of chemical reactions, and then they mixed them together so that disulfide bonds could form. While the synthetic insulin was functional, the production process was very difficult, time intensive, expensive, and could not be scaled up to produce enough insulin to meet the needs of diabetic patients Another method was used by the pharmaceutical company Novo Nordisk A/S to chemically produce human insulin in the early 1970s. Scientists first purified insulin from pigs, which only differs from human insulin by a single amino acid. They then chemically treated the porcine insulin to change that single amino acid to the human amino acid, thereby producing human insulin. Novo Nordisk A/S marketed this product as "semi-synthetic" human insulin However, other events that occurred during this time period led to the production of human insulin in a dramatically different and more effective way, as we shall see next. Questions at are some of the criteria a pharmaceutical company would want to meet if it is producing a drug for sale to consumers 2. How do cells make proteins? Give a general overview of the process 3. Do you think it is possible to exploit the biological process of protein synthesis to make human proteins in the lab? What would you need to do this? Describe the general process you would need to follow to accomplish this goal

Do you think it is possible to exploit the biological process of protein synthesis to make human proteins in the lab? What would you need to do this? Describe the general process you would need to follow to accomplish this goal.

Answer 1

With the 8ntroduction of the field of genetic engineering, it has become possible to synthesise protiens outside body in vivo.

The first gene product that was produced through genetic engineering was a protien, human insulin with the aim to treat diabetes.

A rod shaped bacteria called E. Coli is used for the synthesis of this protien. These bacteria were grown in laboratory and human insulin gene was transferred into the bacteria through recombinant DNA technology. Bacteria was able to express the gene and synthesise insulin. These bacteria are grown in bioreactors for the large scale production of insulin which is then extracted from these bioreactors, purified, processed and is finally made ready for use.

Therefore protiens can be synthesised in laboratory. The various steps involved are.

1. Finding the gene that encodes the protien to be synthesised.

2. Cutting the gene by the help of specific restriction enzymes and pasting it in a suitable vector to form.recombinant DNA.

3. This recombinant DNA is transferred into a suitable host such as E. Coli.

Now E.coli is ready to synthesise the protien.

One of the important jobs for the biotechnologist is to create the perfect environment for the cells to grow and thrive. Nutrients and oxygen must be delivered in exact quantities, the optimum temperature and pH must be maintained, and waste products must be removed.

The cells that are going to produce the protein need to be able to be grown in large amounts. Bioreactors are used to grow cells under conditions where they will make proteins. A bioreactor provides cells with all the substances they need to grow and reproduce.