production of human insulin by rDNA technology

 The production of human insulin using recombinant DNA (r-DNA) technology is a significant milestone in biotechnology and medicine, revolutionizing diabetes treatment. Here’s an overview of the process:

1. Understanding Insulin

Human insulin is a hormone produced by the pancreas, which regulates glucose levels in the blood. In individuals with diabetes, particularly type 1 diabetes, the body does not produce enough insulin, necessitating insulin injections.

2. Challenges with Earlier Insulin Sources

Prior to recombinant DNA technology, insulin for therapeutic use was extracted from the pancreases of pigs and cows. While effective, animal-derived insulin had differences from human insulin that sometimes led to allergic reactions and variations in potency.

3. Steps in Producing Human Insulin Using rDNA Technology

The advent of genetic engineering enabled scientists to produce human insulin synthetically, bypassing the limitations of animal insulin. The basic steps involved are:

a. Gene Identification and Isolation

• The first step is to identify and isolate the gene responsible for producing insulin in humans. Insulin consists of two polypeptide chains: A-chain and B-chain, which are encoded by the INS gene.

b. Gene Cloning

• The insulin gene is inserted into a plasmid (a small, circular piece of DNA) which acts as a vector. This plasmid can replicate independently inside a host cell.
• The plasmid containing the human insulin gene is introduced into bacterial cells, usually Escherichia coli (E. coli), which can reproduce rapidly, creating multiple copies of the insulin gene.

c. Protein Expression

• Inside the bacterial cells, the plasmid instructs the bacteria to produce the insulin protein. However, insulin is produced initially in the form of a preproinsulin, which requires further processing.

d. Separation of Insulin Chains

• Once expressed, the A and B chains of insulin are produced separately and later combined. In early processes, these chains were synthesized separately in bacteria and then chemically combined to form active insulin.

e. Purification

• The insulin produced by the bacteria is extracted and purified. This step ensures that the final insulin product is free of bacterial contaminants and any non-insulin proteins.

f. Post-processing and Formulation

• After purification, the insulin chains are combined chemically in the proper ratio to form functional insulin. The resulting insulin is identical to human insulin and can be administered to patients.

4. Modern Advancements

• Today, yeast cells, particularly strains like Saccharomyces cerevisiae, are also used to produce recombinant insulin. Yeast has advantages over bacteria in terms of protein folding, reducing the need for extensive chemical processing.
• Additionally, insulin analogs are produced using similar r-DNA techniques but with slight modifications to improve their pharmacokinetics (e.g., faster onset or longer duration of action), offering patients more flexible treatment options.

5. Benefits of r-DNA Insulin

• Safety and Efficacy: Recombinant insulin is structurally identical to human insulin, significantly reducing the risk of allergic reactions.
• Scalability: The use of microbial systems like bacteria and yeast enables mass production of insulin, meeting global demand.
• Cost-Effective: Large-scale production in microorganisms is more economical than extraction from animal pancreases.
• Purity: The insulin produced through r-DNA technology is highly purified, minimizing impurities that could affect patient health.

Recombinant DNA technology has transformed the production of human insulin, improving the quality of life for millions of diabetes patients worldwide. By harnessing microorganisms and genetic engineering, scientists have created an efficient, scalable, and safe method to produce insulin identical to the human form, thus minimizing side effects and enhancing treatment flexibility.