Correct option is B
Explanation-
A. 3-dimensional structure → I. Nuclear Magnetic Resonance (NMR)
The 3D structure of a protein refers to its tertiary and quaternary structure, which includes the spatial arrangement of atoms. Nuclear Magnetic Resonance (NMR) spectroscopy is a powerful technique used to determine the 3D structures of small to medium-sized proteins in solution. NMR detects the magnetic properties of atomic nuclei and provides information about atomic distances and angles.
B. Ionic Charge → II. Isoelectric Focusing
Proteins carry different net charges depending on the pH due to their amino acid side chains. Isoelectric focusing separates proteins based on their isoelectric point (pI)—the pH at which a protein carries no net charge. In a pH gradient gel, proteins migrate until they reach the pH = pI and then stop, effectively separating them by charge.
C. Binding specificity → III. Affinity Chromatography
Binding specificity refers to a protein's ability to bind specifically to a particular ligand or molecule. Affinity chromatography exploits this property by immobilizing the ligand on a column matrix. Only proteins with the correct binding sites will bind; others wash away. Bound proteins are then eluted under special conditions.
D. Molecular Size → IV. Ultracentrifugation
Molecular size affects how molecules behave in a centrifugal field. Ultracentrifugation uses high-speed spinning to separate macromolecules based on size and shape. Larger, heavier proteins sediment faster than smaller ones. It can be analytical (for determining molecular weight) or preparative (for separation).
Final Matching:
A – I, B – II, C – III, D – IV
Correct Answer: Option b — A-I, B-II, C-III, D-IV
