(MODEL PAPER) 79. A biochemist purifies a new enzyme, generating the following purification table. The most effective purification step is (1) iv. (2) iii. (3) v (4) ii.

The correct answer is (1) iv. Affinity chromatography.


Introduction

Enzyme purification is a multistep process designed to isolate proteins from complex biological mixtures. Each stage serves to increase the purity and specific activity of the desired enzyme, but not all steps contribute equally. Effective purification is typically identified by dramatic increases in specific activity and reduction of contaminating proteins. This guide analyzes a typical purification table to identify the most effective purification step—in this case, affinity chromatography.


Purification Table Analysis

Step Protein (mg) Activity (units)
Crude Extract 20,000 4,000,000
Salt precipitation 5,000 3,000,000
Ion-exchange 200 800,000
Affinity chromatography 50 750,000
Size-exclusion chromatography 45 675,000

The effectiveness of a step is measured by greatest increase in specific activity:

Specific activity=Activity (units)Protein (mg)


Specific Activity Change

  • Before affinity chromatography: Ion-exchange (III): 800,000/200=4,000 units/mg

  • After affinity chromatography (IV): 750,000/50=15,000 units/mg

Affinity step boosts specific activity almost 4-fold, reflecting comprehensive removal of contaminants and retention of most enzyme activity.


Why Affinity Chromatography Is Best

  • Design: Uses specific ligand binding to isolate only the enzyme.

  • Effectiveness: Yields highest purity and specific activity over other methods, evident from large protein reduction with minimal activity loss.

  • Result: Maximally enriches enzyme, removes non-specific proteins and inhibitors.


Explanation of Other Steps

  • Salt precipitation and ion-exchange remove some contaminants but less selectively; specific activity rises more modestly.

  • Size-exclusion chromatography gives only slight improvement in purity.


Summary Table for Step Effectiveness

Step Specific Activity (units/mg)
Crude Extract 200
Salt precipitation 600
Ion-exchange 4,000
Affinity chromatography 15,000
Size-exclusion chromatography 15,000

Conclusion

Affinity chromatography (step iv) stands as the most effective purification technique in this process due to its sharp increase in specific activity with minimal activity loss. Its molecular selectivity ensures superior enzyme enrichment compared to all other steps.

44 Comments
  • yashika
    September 12, 2025

    Affinity chromatogeaphy

    • Mahima Sharma
      September 13, 2025

      Affinity chromatography

  • Rishita
    September 12, 2025

    Affinity chromatography is the right answer

    • Vijay Marmat
      September 12, 2025

      Affinity chromatography ✔️

  • Kirti Agarwal
    September 12, 2025

    Affinity chromatography is best technique for enzyme purification

  • Khushi Vaishnav
    September 12, 2025

    The most effective purification technique is affinity chromatography

  • Khushi Vaishnav
    September 12, 2025

    The most effective purification technique is affinity chromatography .

  • Sakshi yadav
    September 12, 2025

    Affinity chromatography

    • anjani sharma
      September 12, 2025

      Affinity chromatography is the most effective technique

  • Kajal
    September 12, 2025

    Affinity chromatography

  • Neelam Sharma
    September 12, 2025

    Affinity chromatography for enzyme purification kyunki esk ley speci activity jyada h so enzyme purification k ley most effective tec. Is affinity chromatography

  • Mitali saini
    September 13, 2025

    The correct answer is (1) iv. Affinity chromatography

  • Varsha Tatla
    September 13, 2025

    Affinity chromatography

  • Anju
    September 13, 2025

    Ans: affinity chromatography because it separate the molecule with high affinity

  • Savita Garwa
    September 13, 2025

    Affinity chromatography is best technique for enzyme purification

  • Kanica Sunwalka
    September 13, 2025

    specific activity = units /mg
    on calculation , affinity chromatography have high specific activity ( with minimal activity loss )
    therefore its the most effective purification technique .

  • Kajal
    September 13, 2025

    Option A is correct as affinity chromatography is best for enzyme purification due to its design, effectiveness and result…

  • Konika Naval
    September 13, 2025

    Affinity chromatography

  • Aartii sharma
    September 13, 2025

    Affinity chromatography

  • Asha Gurzzar
    September 13, 2025

    Affinity chromatography

  • Aakansha sharma Sharma
    September 13, 2025

    specific activity =activity (units) / protein (mg)
    on calculation , affinity chromatography have high specific activity ( with minimal activity loss ) So it is most effective purification technique .

  • MOHIT AKHAND
    September 13, 2025

    (1) Affinity chromatography

  • Parul Yadav
    September 14, 2025

    The most effective purification step is affinity chromatography as it has increased specific activity by
    4-fold.

  • Deekshita
    September 14, 2025

    Affinity chromatography

  • Pratibha Jain
    September 14, 2025

    Affinity chromatography is best technique for enzyme purification

  • Payal Gaur
    September 14, 2025

    Affinity chromatography for enzyme purification

  • Meera gurjar
    September 14, 2025

    Affinity

  • Meera gurjar
    September 14, 2025

    By Affinity

  • Pallavi Ghangas
    September 14, 2025

    Affinity chromatography is best out of all as it gives high yield and is specific and remove non specific protein

  • anjani sharma
    September 14, 2025

    Affinity chromatography is the best technique as it removes non-specific proteins and inhibitors

  • Palak Sharma
    September 14, 2025

    specific activity for affinity chromatography is the highest. So it is the best technique.

  • Dharmpal Swami
    September 14, 2025

    Affinity chromatography

  • Lokesh Kumawat
    September 14, 2025

    Affinity chromatography

  • Priya dhakad
    September 14, 2025

    Affinity chromatography is the most effective purification technique.

  • Divya rani
    September 14, 2025

    Affinity chromatography is the best technique for purification of enzyme or protein. It maintain the specific Binding and dissociate the non specific Binding.

  • Vanshika Sharma
    September 15, 2025

    Affinity chromatography

  • Bhawna Choudhary
    September 15, 2025

    Affinity chromatography

  • Sheikh Aleen
    September 15, 2025

    Affinity chromatography

  • Soniya Shekhawat
    September 15, 2025

    Affinity chromatography is best technique for enzyme purification.

  • Nilofar Khan
    September 16, 2025

    correct answer is 1
    Affinity chromatography is best tech. For enzyme purification

  • Mohd juber Ali
    September 16, 2025

    Option 1
    Affinity chromatography

  • Muskan Yadav
    September 17, 2025

    Affinity chromatography is the right answer

  • Neelam Sharma
    September 23, 2025

    Affinity chromatography (step iv) stands as the most effective purification technique in this process due to its sharp increase in specific activity with minimal activity loss. Its molecular selectivity ensures superior enzyme enrichment compared to all other steps.

  • Aafreen Khan
    September 23, 2025

    Affinity chromatography is best technique for enzyme purification

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