Two different antibodies against the same protein were generated and named AB1 and AB2. While AB1 was able to detect the target protein in a western blot, it was unable to detect the protein in ELISA. The opposite was true for AB2. Which one of the following is the most likely reason?

Correct option is D

Correct Answer:  (d)
Explanation: In western blotting, proteins are denatured due to SDS and reducing agents, exposing linear (continuous) epitopes. Antibodies recognizing these linear epitopes can bind effectively in western blot. ELISA, however, often detects proteins in a more native or folded conformation, where discontinuous epitopes are preserved. Therefore, AB1 detects linear epitopes on unfolded protein, whereas AB2 recognizes conformational epitopes on the folded protein.
Information Booster
· Western blotting involves protein denaturation using SDS.
· Linear epitopes consist of continuous amino acid sequences.
· ELISA often preserves native protein conformation.
· Conformational (discontinuous) epitopes depend on protein folding.
· Antibody specificity depends strongly on epitope structure and protein state.
Additional Knowledge
Antibodies recognizing conformational epitopes generally fail in western blot because denaturation disrupts epitope structure. Conversely, antibodies that bind linear epitopes may not recognize the native protein structure efficiently in ELISA. Understanding epitope specificity is critical for selecting antibodies for appropriate immunodetection techniques.