Protein Separation Techniques Matching Question: GATE Life Sciences Solved
Glycine and albumin separation, along with histones and lectins, requires specific chromatography and dialysis methods for precise purification in biochemistry. This detailed solution to Q39 explains matching Group 1 items with Group 2 techniques, ideal for competitive exam prep like GATE Life Sciences.
Question Breakdown
Group 1 lists protein mixtures needing separation:
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P: Glycine (small ~75 Da amino acid) and albumin (~66 kDa protein).
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Q: 20 kDa and 60 kDa proteins (size difference).
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R: Histones from nuclear extract (basic proteins).
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S: Lectins (sugar-binding proteins).
Group 2 techniques:
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Gas chromatography (volatiles, not proteins).
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Dialysis (size-based membrane filtration).
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Affinity chromatography (ligand-specific binding).
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Size exclusion chromatography (SEC; molecular weight separation).
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Thin layer chromatography (small molecules, not proteins).
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Cation exchange chromatography (positive charge binding).
Matching Explanations
P. Mixture of glycine and albumin → 2. Dialysis
Glycine passes through dialysis membranes (cutoff ~1-10 kDa), while large albumin is retained. This size-based technique separates small solutes from macromolecules without denaturation.
Q. Mixture of 20 and 60 kDa proteins → 4. Size exclusion chromatography
SEC separates by hydrodynamic volume; smaller 20 kDa elutes later than larger 60 kDa. Ideal for native protein mixtures by size alone.
R. Histones from nuclear extract → 6. Cation exchange chromatography
Histones are highly basic (lysine/arginine-rich), binding strongly to cation exchangers at low pH. Nuclear extracts contain contaminants; this purifies via charge.
S. Lectins → 3. Affinity chromatography
Lectins bind specific carbohydrates; use sugar-immobilized matrices (e.g., glucose columns) for selective elution. Gold standard for carbohydrate-binding proteins.
Option Analysis
| Option |
P |
Q |
R |
S |
Correct? |
Reason |
| (A) |
1 |
4 |
3 |
5 |
No |
Gas/TLC unsuitable for proteins; histones not affinity-specific here |
| (B) |
5 |
3 |
6 |
1 |
No |
TLC/gas wrong for proteins; Q not affinity |
| (C) |
2 |
4 |
6 |
3 |
Yes |
Matches all: dialysis (size), SEC (size), cation (charge), affinity (specific) |
| (D) |
6 |
5 |
2 |
4 |
No |
Cation wrong for small glycine; TLC/SEC swapped incorrectly |
Correct answer: (C) P-2, Q-4, R-6, S-3.
