Q.59 Given below are two statements :
Statement I :
Ion exchange chromatography exploits differences in the sign and magnitude
of the net electric charge of proteins at a given pH.
Statement II :
In ion exchange chromatography, separation can be optimized by gradually
changing the pH and/or salt concentrations of the mobile phase to create
a pH or salt gradient.
In the light of the above statements, choose the correct answer from the options given below :
- Both Statement I and Statement II are correct
- Both Statement I and Statement II are incorrect
- Statement I is correct but Statement II is incorrect
- Statement I is incorrect but Statement II is correct
Both statements about ion exchange chromatography are correct, making the first option the right answer. This technique separates proteins based on charge differences at specific pH levels, with optimization via pH or salt gradients in the mobile phase.
Core Mechanism
Ion exchange chromatography uses charged resins to bind proteins with opposite charges. Proteins’ net charge depends on pH relative to their isoelectric point (pI)—positive below pI, negative above—enabling selective binding and separation.
Statement Breakdown
-
Statement I (Correct): Separation relies on differences in net electric charge (sign and magnitude) of proteins at a fixed pH, as charged proteins interact electrostatically with the resin.
-
Statement II (Correct): Gradual changes in pH or salt concentration (gradients) elute bound proteins by weakening interactions—weaker binders elute first at low salt, stronger at higher.
Option Analysis
| Option |
Why Valid/Invalid |
Correct? |
| Both correct |
Matches charge-based separation and gradient elution standards. |
Yes |
| Both incorrect |
Contradicts established principles of protein purification. |
No |
| I correct, II incorrect |
Ignores routine use of salt/pH gradients for resolution. |
No |
| I incorrect, II correct |
Denies fundamental charge exploitation role. |
No |
Ion exchange chromatography protein net charge separation at specific pH with salt gradient optimization is key for biotech purification, vital for GATE Life Sciences preparation.
Charge-Based Separation
Resins (cation: negative; anion: positive) bind oppositely charged proteins. Net charge varies by pH vs. pI, driving high-resolution isolation.
Gradient Elution Strategy
Salt gradients compete ionic bonds; pH shifts alter charges. Weakly bound proteins elute early, enhancing purity.
Exam Application
Both statements affirm core technique: charge exploitation (I) and gradient tuning (II), selecting option (1).
