Question

Which of the following methods can be used to detect a protein band in an organelle fraction for which there is no enzyme assay? A monoclonal antibody specific for the protein is available and each fraction obtained from the fractionation experiment will be assayed.

a. Immunofluorescence

b. Western blotting

c. Immunoelectron microscopy

d. ELISA assay

Answer 1

The processes of western blotting and ELISA both involve enzymatic reactions to detect the protein band, and in both cases, the secondary antibody is tagged with an enzyme that acts on a substrate to give a product that gives us a measure of the protein.

In case of immunofluorescence also the secondary antibody is attached to a fluorophore that when excited gives a colored signal.

In case of immune electron microscopy, the secondary antibody is gold conjugated and thus creates a coat that helps us to visualize the protein, so it does not involve any enzymatic reaction.

So a method used to detect a protein band in an organelle fraction for which there is no enzyme assay is Immunoelectron microscopy( option c)