A mixture of three proteins (X, Y and Z) was loaded on a size exclusion column. [Table] The correct order of elution of the proteins from the column…
A mixture of three proteins (X, Y and Z) was loaded on a size exclusion column.
The correct order of elution of the proteins from the column is
| Protein | MW (KD) | pI |
|---|---|---|
| X | 140.75 | 5.5 |
| Y | 22.3 | 10.1 |
| Z | 88.6 | 2.8 |
Select an option to attempt
Correct Answer: Option A
Explanation
Size exclusion chromatography (SEC/GFC) elution order: Larger molecules elute FIRST (excluded from pores; shorter path through column); smaller molecules elute LAST (enter pores; longer effective path). Given proteins from the table: X = 140.75 kDa (largest), Z = 88.6 kDa (medium), Y = 22.3 kDa (smallest). Elution order (first to last): X → Z → Y. Column elution: X, Z, Y. This is the reverse of molecular weight order in denaturing SDS-PAGE. In native SEC, the hydrodynamic radius (, Stokes radius) — not just MW — determines elution; however for globular proteins of similar shape,, and larger MW → larger→ earlier elution.