Biocatalysis and immobilized enzyme applications MCQs With Answer

Biocatalysis and immobilized enzyme applications MCQs With Answer

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Introduction: Biocatalysis and immobilized enzyme applications are pivotal in modern pharmaceutical manufacturing, offering selective, efficient, and greener routes to complex molecules. This quiz set is designed for M.Pharm students to reinforce core concepts of enzyme catalysis, immobilization techniques (adsorption, covalent binding, entrapment, encapsulation, cross-linking), effects on kinetics and stability, reactor configurations, and real-world pharmaceutical applications such as chiral synthesis and antibiotic modification. Questions probe theoretical principles, characterization methods, operational challenges like mass transfer limitations and enzyme leaching, and strategies for cofactor regeneration and stabilization. Use these MCQs to test understanding, prepare for exams, and apply knowledge to process design and scale-up in pharma biocatalysis.

Q1. What is the primary advantage of immobilizing an enzyme on a solid support for industrial processes?

  • Increased solubility of enzyme in organic solvents
  • Improved enzyme recyclability and operational stability
  • Complete elimination of mass transfer limitations
  • Guaranteed increase in intrinsic catalytic rate (kcat)

Correct Answer: Improved enzyme recyclability and operational stability

Q2. Which immobilization method involves forming covalent bonds between enzyme functional groups and activated support surfaces?

  • Physical adsorption
  • Covalent binding
  • Entrapment in alginate beads
  • Encapsulation within liposomes

Correct Answer: Covalent binding

Q3. Entrapment of enzymes in calcium alginate beads primarily affects enzyme performance by:

  • Eliminating enzyme leaching completely
  • Altering the enzyme’s primary amino acid sequence
  • Introducing diffusional limitations for substrates and products
  • Forming covalent enzyme-support linkages

Correct Answer: Introducing diffusional limitations for substrates and products

Q4. Multipoint covalent attachment of enzymes to a support is used mainly to:

  • Increase enzyme turnover number by mutation
  • Improve thermal and operational stability by restricting conformational mobility
  • Enhance substrate diffusion into the active site
  • Convert a monomeric enzyme into a multimeric complex

Correct Answer: Improve thermal and operational stability by restricting conformational mobility

Q5. Which parameter best describes the fraction of immobilized enzyme activity retained after immobilization relative to the initial free enzyme activity?

  • Immobilization yield
  • Activity recovery
  • Loading capacity
  • Turnover frequency

Correct Answer: Activity recovery

Q6. In Michaelis–Menten kinetics for an immobilized enzyme, an apparent increase in Km is most often attributed to:

  • Higher intrinsic affinity of enzyme for substrate
  • Mass transfer (diffusional) limitations within the immobilisate
  • Complete denaturation of the enzyme
  • Increase in cofactor concentration

Correct Answer: Mass transfer (diffusional) limitations within the immobilisate

Q7. Which reactor type is most commonly used for continuous processing with immobilized enzymes in packed form?

  • Batch stirred-tank reactor
  • Packed-bed (fixed-bed) reactor
  • Membrane dialysis reactor
  • Photobioreactor

Correct Answer: Packed-bed (fixed-bed) reactor

Q8. What is the Thiele modulus used to evaluate in immobilized enzyme systems?

  • Thermal stability of enzyme-support conjugates
  • Ratio of reaction rate to internal diffusion rate in porous particles
  • Degree of covalent attachment sites per enzyme molecule
  • Extent of leaching during repeated cycles

Correct Answer: Ratio of reaction rate to internal diffusion rate in porous particles

Q9. Which support material is naturally derived and frequently used for entrapment and gel-based immobilization in pharma labs?

  • Sepharose (agarose)
  • Eupergit C (glycidyl methacrylate resin)
  • Polystyrene-divinylbenzene resin
  • Synthetic silica nanoparticles only

Correct Answer: Sepharose (agarose)

Q10. Cross-linked enzyme aggregates (CLEAs) are formed by:

  • Adsorbing enzyme onto ion-exchange resins without cross-linking
  • Precipitating the enzyme and then cross-linking aggregates with bifunctional reagents
  • Entrapping enzyme in micelles
  • Genetically fusing enzyme to a carrier protein

Correct Answer: Precipitating the enzyme and then cross-linking aggregates with bifunctional reagents

Q11. Which analytical technique is commonly used to confirm covalent attachment and changes in functional groups after enzyme immobilization?

  • NMR spectroscopy of whole immobilisate without pretreatment
  • FTIR spectroscopy to detect new bond vibrations
  • Optical microscopy for primary sequence analysis
  • Mass spectrometry of support alone

Correct Answer: FTIR spectroscopy to detect new bond vibrations

Q12. Immobilized lipases are widely applied in pharmaceutical synthesis primarily for:

  • Non-selective hydrolysis of proteins
  • Enantioselective transesterification and kinetic resolution of racemates
  • Oxidative deamination of amines
  • Photochemical isomerization of double bonds

Correct Answer: Enantioselective transesterification and kinetic resolution of racemates

Q13. A major challenge when using immobilized enzymes in organic solvents is:

  • Excessive enzyme hydration leading to overactivity
  • Denaturation due to removal of essential bound water and changed conformation
  • Support materials dissolving in water
  • Increase in enzyme gene expression

Correct Answer: Denaturation due to removal of essential bound water and changed conformation

Q14. Cofactor-dependent enzymes immobilized for NAD(P)H-utilizing reactions in pharma processes often require:

  • Permanent chemical inactivation of cofactors
  • Strategies for cofactor regeneration or co-immobilization of regeneration systems
  • Removal of all cofactors to make reactions faster
  • Use of only whole-cell systems that cannot regenerate cofactors

Correct Answer: Strategies for cofactor regeneration or co-immobilization of regeneration systems

Q15. Which statement about enzyme leaching from non-covalent immobilisates is correct?

  • Leaching is impossible when adsorption is used
  • Leaching reduces operational stability and can contaminate product streams
  • Leaching always increases catalytic turnover
  • Leaching converts the immobilized enzyme into a covalent form

Correct Answer: Leaching reduces operational stability and can contaminate product streams

Q16. Activity recovery of an immobilized enzyme is calculated as the ratio of:

  • Total protein bound to support to support mass
  • Enzyme activity after immobilization to enzyme activity before immobilization
  • Support surface area to enzyme molecular weight
  • Number of cycles run to total operational time

Correct Answer: Enzyme activity after immobilization to enzyme activity before immobilization

Q17. Which design consideration becomes critical when scaling up packed-bed reactors with immobilized enzymes for high substrate concentration feeds?

  • Avoiding any pressure drop across the bed regardless of particle size
  • Managing external mass transfer and pressure drop while preventing channeling and maintaining residence time
  • Using the highest possible bed height without flow control
  • Irradiating the bed with UV to enhance activity

Correct Answer: Managing external mass transfer and pressure drop while preventing channeling and maintaining residence time

Q18. In immobilized enzyme systems, the effectiveness factor (η) is defined as:

  • The fraction of enzyme that becomes covalently attached
  • The ratio of observed reaction rate of immobilized enzyme to the rate if all enzyme were fully accessible with no diffusion limitation
  • The amount of enzyme leached per cycle
  • The percentage increase in Km after immobilization

Correct Answer: The ratio of observed reaction rate of immobilized enzyme to the rate if all enzyme were fully accessible with no diffusion limitation

Q19. Which immobilization approach is most suitable when simple recovery and low-cost supports are priorities for bulk biocatalytic processes?

  • Immobilization on expensive functionalized synthetic resins only
  • Adsorption on inexpensive porous carriers or entrapment in inexpensive gels
  • Covalent multipoint attachment on bespoke supports exclusively
  • Cross-linking only without any carrier

Correct Answer: Adsorption on inexpensive porous carriers or entrapment in inexpensive gels

Q20. For immobilized enzymes used in stereoselective pharmaceutical synthesis, which combination often yields the best enantioselectivity and reusability?

  • Free enzyme in batch with organic solvent and no immobilization
  • Rational enzyme engineering (mutagenesis) combined with immobilization on an appropriate support and process optimization
  • Random adsorption on hydrophobic beads without screening
  • Using only whole-cell biocatalysts regardless of mass transfer issues

Correct Answer: Rational enzyme engineering (mutagenesis) combined with immobilization on an appropriate support and process optimization

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