(DEC 2013 GU)
78. You have isolated spleen cells and purified your desired enzyme from the spleen cell extract by a sequence of steps involving ammonium sulfate fractionation and gel chromatography. You found an increase in the specific activity of the enzyme in the purified fraction compared to cell free extract and made the following speculations:
A. Cell free extract contained inhibitor bound enzyme
B. Structure of the enzyme was modified during the course of purification
C. Purification steps gradually removed the inhibitors
D. The final fraction contained concentrated enzyme preparation
Which one of the following combination is appropriate?
(1) A, B and D (2) A, C and D
(3) A, B and C (4) B, C and D
The correct answer is (2) A, C and D.
Introduction
Purification of enzymes from complex biological extracts is a cornerstone of biochemical research. The process often results in an increase in specific activity, reflecting a higher ratio of enzyme to total protein. This increase can be explained by removal of inhibitors, concentration of the enzyme, and preservation of enzyme structure. This article discusses why certain key factors like inhibitor removal and enzyme concentration are responsible for increased specific activity, while discounting unlikely causes such as structural modification during purification.
Understanding Specific Activity Increase
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Specific activity = enzyme activity per mg protein
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An increase indicates either more enzyme relative to other proteins or reduction of enzyme inhibitors.
Explanation of Statements
A. Cell free extract contained inhibitor bound enzyme
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In crude extracts, enzymes often bind inhibitors or exist in inactive forms lowering their apparent activity.
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This contributes to low specific activity in crude extracts.
B. Structure of the enzyme was modified during purification
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Usually undesirable; structural modification often leads to loss of enzyme activity.
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Not a reason for increase in specific activity but rather potential loss.
C. Purification steps gradually removed inhibitors
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Ammonium sulfate fractionation and chromatography remove non-enzyme proteins including inhibitors.
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Removing inhibitors increases measurable enzyme activity.
D. The final fraction contained concentrated enzyme preparation
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Concentration of enzyme during purification increases fraction’s specific activity as protein contaminants are lost.
Reasoning for Correct Combination (A, C, D)
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Statements A, C, and D provide a logical chain:
Inhibitors are removed (C), previously bound inhibitory complexes present (A), enzyme is concentrated (D) → all leading to increased specific activity. -
Statement B conflicts with typical enzyme purification goals.
Practical Implications
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Enzyme purification relies on maintaining enzyme structure and removing inhibitory contaminants.
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Specific activity measurements are key quality checks in purification protocols.
Summary Table
Statement | Interpretation | Validity |
---|---|---|
A | Inhibitor bound enzyme in extract | True |
B | Enzyme structurally altered | False |
C | Removal of inhibitors during purification | True |
D | Enzyme concentrated in final fraction | True |
Conclusion
The increase in specific activity of the purified enzyme is best explained by the presence of inhibitors in the crude extract, removal of these inhibitors through purification steps, and concentration of enzyme, represented by option (2) A, C, and D.
36 Comments
yashika
September 12, 2025Presence if inhibitir in crude extract
Kirti Agarwal
September 12, 2025Opt A, C, D
Mahima Sharma
September 13, 2025A,c,d
Khushi Vaishnav
September 12, 2025ACD is the right option
Sakshi yadav
September 12, 2025Cell free extract contained inhibitor bound enzyme
C. Purification steps gradually removed the inhibitors
D. The final fraction contained concentrated enzyme preparation
Neelam Sharma
September 12, 2025A. Cell free extract contained inhibitor bound enzyme
C. Purification steps gradually removed the inhibitors
D. The final fraction contained concentrated enzyme preparation
A,c,d right h
Kyunki starting me inhibitors enzyme k sath bind krnge but jese jese purification hota jayega bese bese inhibitors htate jaynge or purified enzyme ki specific activity increase hojayegi
Ye koi modification nhi h enzyme ka purification k time or purification gradual process ho rhi h
Kajal
September 13, 2025A, C, and D
Inhibitors are removed (C), previously bound inhibitory complexes present (A), enzyme is concentrated (D) → all leading to increased specific activity.
Varsha Tatla
September 13, 2025Inhibitors bound enz in extract
Removal of inhibitors during purification
Enz conc in fraction
Savita Garwa
September 13, 2025Option 2 ACD correct answer…
Kajal
September 13, 2025Option 2means ACD is correct answer bcz modification in enzyme structure leads to decrease in enzyme activity…
Kanica Sunwalka
September 13, 2025specific activity of enzyme -increased when
* crude extract contains inhibitor bounded enzymes
* inhibitors less – enzyme activity increases
* concentrated enzyme – specific activity increases
so , option 2 is correct
Rishita
September 13, 2025Option 2
Aartii sharma
September 13, 2025A,c&D
Asha Gurzzar
September 13, 2025A,c,d are correct (option b)
Aakansha sharma Sharma
September 13, 2025A. Cell free extract contained inhibitor bound enzyme
C. Purification steps gradually removed the inhibitors
D. The final fraction contained concentrated enzyme preparation
All (A,c,d ) is correct
Vijay Marmat
September 14, 2025✔️
MOHIT AKHAND
September 14, 2025Enzyme’s activity loss due to structural modification.
Pratibha Jain
September 14, 2025correct answer is option (2) A, C and D.
Divya rani
September 14, 2025ACD is right answer because enzyme activity increase when cell free extract contain inhibitor bound enzyme , purification step gradually remove the inhibitor and final fraction contain concentrated enzyme or protein.
Santosh Saini
September 14, 2025Correct answer is option (2) A, C,D
Meera gurjar
September 14, 2025A, C, D
Meera gurjar
September 14, 2025A, C,and D
Meera gurjar
September 14, 2025A, C,and D is the answer
Meera gurjar
September 14, 2025Option A, C,and D is the answer
Parul Yadav
September 14, 2025Specific activity of the enzyme increased in the purified fraction as compared to the cell free extract because cell free extract contained inhibitor bound enzyme and purification steps gradually removed the inhibitors.
Pallavi Ghangas
September 14, 2025Second option is incorrect which is the structure of enzyme get modified because if this was the case then there should be no activity rather then less activities because all the enzymes are in this same environment if structure modification happen it should be for all the enzyme and hence no activity
Palak Sharma
September 14, 2025enzyme activity increased due to following reasons :
A. Cell free extract contained inhibitor bound enzyme
C. Purification steps gradually removed the inhibitors
D. The final fraction contained concentrated enzyme preparation
Lokesh Kumawat
September 14, 2025Acd
Priya dhakad
September 14, 2025The increase in specific activity of the purified enzyme is best explained by the presence of inhibitors in the crude extract, removal of these inhibitors through purification steps, and concentration of enzyme. So A, C, D option is correct.
Soniya Shekhawat
September 15, 2025👉 Specific activity = enzyme activity ÷ total protein.
If specific activity increases, it usually means inhibitors and contaminating proteins were removed. So in A,C,D in this show increase of enzyme activity means increase of specific activity.
Payal Solanki
September 18, 2025Option 2 A,C,D
priya khandal
September 17, 2025option a c d is right
Muskan Yadav
September 17, 2025A. Cell-free extract contained inhibitor-bound enzyme
C. Purification steps gradually removed the inhibitors
D. The final fraction contained concentrated enzyme preparation
A, C, and D are correct.
Because in the beginning, inhibitors are bound to the enzyme, but as purification proceeds, the inhibitors are gradually removed, and the specific activity of the purified enzyme increases.
This is not a modification of the enzyme — it is happening during purification, and purification is a gradual process.
Tanvi Panwar
September 17, 2025The crude extract contains inhibitors so by their purification inhibitors are removed and their specific activity increases. Purification of enzymes removes non enzymatic proteins including inhibitors and the final step contained concentrated enzyme preparation. so option A C and D are correct.
Minal Sethi
September 19, 2025option 2
A,C and D
Aafreen Khan
September 23, 2025A,C,D are the correct answer