Microbial Production of Pharmaceuticals
Somatostatin, Humulin and Interferons
1. Introduction
Advances in recombinant DNA technology have enabled microorganisms to produce human therapeutic proteins safely, economically and in large quantities. Microbial systems such as Escherichia coli and yeast (Saccharomyces cerevisiae) are widely used for the production of pharmaceuticals that were earlier isolated from human or animal tissues.
Important microbial-derived pharmaceuticals include somatostatin, human insulin (Humulin) and interferons.
2. Advantages of Microbial Production of Pharmaceuticals
High yield and rapid production
Cost-effective and scalable
Free from animal pathogens
Consistent product quality
Easy genetic manipulation
3. General Steps in Microbial Production of Recombinant Pharmaceuticals
Isolation of target gene
Construction of recombinant DNA
Insertion into suitable vector
Transformation into host microorganism
Expression of protein
Downstream processing and purification
4. Microbial Production of Somatostatin
About Somatostatin
A 14-amino acid peptide hormone
Inhibits secretion of growth hormone (GH), insulin and glucagon
Used in treatment of acromegaly, endocrine tumors, GI disorders
Production Strategy
Somatostatin is too small and unstable when produced alone in microbes. Hence it is produced as a fusion protein.
Steps Involved
Synthetic DNA coding for somatostatin is prepared
Gene is fused to β-galactosidase gene (lacZ)
Recombinant plasmid is introduced into E. coli
Fusion protein is expressed in large quantity
Fusion protein is purified
Somatostatin is cleaved using cyanogen bromide (CNBr)
Active somatostatin is purified
Significance
First human hormone produced by recombinant DNA technology
Opened the era of recombinant pharmaceuticals
5. Microbial Production of Humulin (Human Insulin)
About Insulin
Hormone regulating blood glucose level
Composed of two polypeptide chains (A and B) linked by disulfide bonds
Used in treatment of diabetes mellitus
Limitations of Animal Insulin
Allergic reactions
Limited supply
Slight structural differences
Recombinant Production Strategy
Insulin is produced either as separate A and B chains or as proinsulin.
Production in E. coli
Synthetic genes for A-chain and B-chain are prepared
Each gene is fused to β-galactosidase gene
Recombinant plasmids introduced into E. coli
A and B chains produced separately
Chains are purified and cleaved from fusion protein
A and B chains are chemically joined to form insulin
Production in Yeast (Saccharomyces cerevisiae)
Proinsulin gene is inserted into yeast plasmid
Yeast expresses proinsulin
Enzymatic processing converts proinsulin to insulin
Commercial Product
Humulin (first recombinant insulin approved in 1982)
6. Microbial Production of Interferons
About Interferons
Group of cytokines with antiviral, anticancer and immunomodulatory properties
Produced naturally by human cells in response to viral infection
Types of Interferons
IFN-α (alpha) – leukocytes
IFN-β (beta) – fibroblasts
IFN-γ (gamma) – T-lymphocytes
Medical Uses
Treatment of viral infections (hepatitis B & C)
Cancer therapy
Multiple sclerosis
Production in Microbes
IFN-α and IFN-β are commonly produced in E. coli
IFN-γ is produced in E. coli or yeast
Production Steps
Isolation of interferon gene (usually IFN-α)
Cloning into expression vector
Transformation into E. coli
Expression of interferon protein
Recovery from inclusion bodies (if formed)
Refolding and purification
Challenges
Formation of inclusion bodies
Lack of post-translational modifications in bacteria
Protein folding issues
7. Downstream Processing
Cell lysis
Protein purification (chromatography)
Refolding of protein
Quality control and formulation
8. Advantages of Recombinant Interferons
High purity
Reduced side effects
Consistent biological activity
10. Applications of Microbial Pharmaceuticals
Treatment of hormonal disorders
Management of diabetes
Antiviral and anticancer therapy
Immunomodulation
11. Conclusion
Microbial production of pharmaceuticals has revolutionized modern medicine by enabling safe, economical and large-scale synthesis of human therapeutic proteins. The successful production of somatostatin, humulin and interferons demonstrates the immense potential of recombinant microorganisms in the pharmaceutical industry and marks a major milestone in biotechnology.
50 MCQs – Microbial Production of Pharmaceuticals
1. Recombinant pharmaceutical proteins are produced mainly using
A. Plants only
B. Animals only
C. Microorganisms
D. Chemicals
✔ Answer: C
2. The most commonly used bacterial host for recombinant protein production is
A. Bacillus subtilis
B. Escherichia coli
C. Pseudomonas aeruginosa
D. Streptomyces
✔ Answer: B
3. Somatostatin is a
A. Enzyme
B. Antibiotic
C. Peptide hormone
D. Vitamin
✔ Answer: C
4. Somatostatin mainly inhibits the secretion of
A. Thyroxine
B. Growth hormone
C. Adrenaline
D. Prolactin
✔ Answer: B
5. Length of somatostatin is
A. 7 amino acids
B. 14 amino acids
C. 21 amino acids
D. 51 amino acids
✔ Answer: B
6. Somatostatin was the first hormone produced by
A. Chemical synthesis
B. Plant tissue culture
C. Recombinant DNA technology
D. Animal extraction
✔ Answer: C
7. Somatostatin gene is usually expressed as a
A. Free peptide
B. Fusion protein
C. Multimer
D. Zymogen
✔ Answer: B
8. β-galactosidase gene used in somatostatin production is
A. trpA
B. lacZ
C. araC
D. tetR
✔ Answer: B
9. Enzyme/chemical used to cleave somatostatin from fusion protein is
A. Trypsin
B. Pepsin
C. Cyanogen bromide
D. Lysozyme
✔ Answer: C
10. Human insulin consists of
A. One polypeptide chain
B. Two polypeptide chains
C. Three polypeptide chains
D. Four polypeptide chains
✔ Answer: B
11. The two chains of insulin are
A. α and β
B. Heavy and light
C. A and B
D. X and Y
✔ Answer: C
12. Total number of amino acids in insulin is
A. 14
B. 21
C. 51
D. 165
✔ Answer: C
13. Insulin deficiency leads to
A. Acromegaly
B. Dwarfism
C. Diabetes mellitus
D. Goitre
✔ Answer: C
14. Commercial recombinant human insulin is called
A. Interferon
B. Somatotropin
C. Humulin
D. Prolactin
✔ Answer: C
15. The first recombinant insulin was approved in
A. 1978
B. 1980
C. 1982
D. 1985
✔ Answer: C
16. Animal insulin differs from human insulin by
A. 1–3 amino acids
B. 5 amino acids
C. 10 amino acids
D. 20 amino acids
✔ Answer: A
17. In E. coli, insulin is produced by
A. Whole insulin gene
B. Proinsulin only
C. Separate A and B chains
D. Mature insulin directly
✔ Answer: C
18. Yeast is preferred for insulin production because
A. It grows faster
B. It performs post-translational modifications
C. It produces antibiotics
D. It forms spores
✔ Answer: B
19. Proinsulin is converted into insulin by
A. Acid hydrolysis
B. Chemical oxidation
C. Enzymatic cleavage
D. Heat treatment
✔ Answer: C
20. Interferons belong to the group of
A. Hormones
B. Enzymes
C. Cytokines
D. Vitamins
✔ Answer: C
21. Interferons are mainly involved in
A. Digestion
B. Photosynthesis
C. Antiviral defense
D. Respiration
✔ Answer: C
22. IFN-α is naturally produced by
A. Fibroblasts
B. T-lymphocytes
C. Leukocytes
D. Macrophages only
✔ Answer: C
23. IFN-β is produced by
A. Leukocytes
B. Fibroblasts
C. T-cells
D. B-cells
✔ Answer: B
24. IFN-γ is produced by
A. Fibroblasts
B. Leukocytes
C. T-lymphocytes
D. Platelets
✔ Answer: C
25. Recombinant interferons are mainly produced in
A. Plants
B. Animals
C. Bacteria and yeast
D. Algae
✔ Answer: C
26. One major medical application of interferons is treatment of
A. Diabetes
B. Cancer
C. Goitre
D. Hypertension
✔ Answer: B
27. Interferons inhibit viral replication by
A. Destroying host DNA
B. Blocking protein synthesis
C. Activating antiviral enzymes
D. Killing host cells
✔ Answer: C
28. Major problem during bacterial expression of interferons is
A. Slow growth
B. Inclusion body formation
C. Low plasmid copy number
D. Antibiotic resistance
✔ Answer: B
29. Inclusion bodies are
A. Secretory vesicles
B. Aggregates of misfolded proteins
C. Ribosomes
D. Cell organelles
✔ Answer: B
30. Refolding of proteins is required after
A. Transcription
B. Translation
C. Inclusion body solubilization
D. Cell growth
✔ Answer: C
31. Downstream processing includes
A. Gene cloning
B. Fermentation only
C. Protein purification
D. Transformation
✔ Answer: C
32. Chromatography is mainly used for
A. Gene isolation
B. Protein purification
C. Cell growth
D. Mutation induction
✔ Answer: B
33. Recombinant pharmaceuticals are safer because
A. They are cheaper
B. They lack pathogens
C. They are plant-derived
D. They are chemically synthesized
✔ Answer: B
34. Which protein is smallest in size?
A. Insulin
B. Interferon
C. Somatostatin
D. Proinsulin
✔ Answer: C
35. Which protein requires formation of disulfide bonds?
A. Somatostatin
B. Insulin
C. Interferon
D. All of the above
✔ Answer: B
36. Cyanogen bromide cleaves proteins at
A. Arginine
B. Lysine
C. Methionine
D. Tryptophan
✔ Answer: C
37. lac operon system is used in
A. Yeast expression
B. Plant expression
C. Bacterial expression
D. Animal cell culture
✔ Answer: C
38. Recombinant insulin reduced
A. Cost of antibiotics
B. Allergic reactions
C. Hormone deficiency
D. Viral infections
✔ Answer: B
39. Interferons are NOT used for
A. Viral infections
B. Cancer therapy
C. Diabetes treatment
D. Multiple sclerosis
✔ Answer: C
40. IFN-α is commonly used to treat
A. Diabetes
B. Hepatitis
C. Acromegaly
D. Goitre
✔ Answer: B
41. Host system offering eukaryotic processing is
A. E. coli
B. Yeast
C. Bacteriophage
D. Virus
✔ Answer: B
42. Recombinant protein expression requires
A. Only host cell
B. Vector and host
C. Chemical synthesis
D. Heat treatment
✔ Answer: B
43. Promoter controls
A. Protein folding
B. Transcription initiation
C. Translation termination
D. Protein cleavage
✔ Answer: B
44. Insulin produced in yeast is usually synthesized as
A. Mature insulin
B. Proinsulin
C. Separate A and B chains
D. Fusion protein
✔ Answer: B
45. First recombinant pharmaceutical approved for human use was
A. Interferon
B. Somatostatin
C. Insulin
D. Growth hormone
✔ Answer: C
46. Recombinant DNA technology helps in
A. Uniform drug quality
B. Large-scale production
C. Reduced contamination
D. All of the above
✔ Answer: D
47. Insulin chains are linked by
A. Hydrogen bonds
B. Ionic bonds
C. Disulfide bonds
D. Peptide bonds
✔ Answer: C
48. Interferons show which activity?
A. Antibacterial
B. Antiviral
C. Antifungal
D. Antiprotozoal
✔ Answer: B
49. Which is NOT a recombinant pharmaceutical?
A. Insulin
B. Interferon
C. Somatostatin
D. Penicillin
✔ Answer: D
50. Microbial pharmaceutical production represents
A. Traditional biotechnology
B. Medical biotechnology
C. Agricultural biotechnology
D. Environmental biotechnology
✔ Answer: B
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