Practical uses of antibodies in the laboratory and medicine: Which of the following represents legitimate applications of antibodies?

Introduction / Context:
Antibodies are versatile tools beyond immunity. Their specificity enables detection, purification, and even catalysis when engineered appropriately.

Given Data / Assumptions:

• High specificity and affinity for target epitopes.
• Antibodies can be immobilized on solid supports.
• Catalytic antibodies (abzymes) can be selected to stabilize transition states.

Concept / Approach:
For localization, labeled antibodies reveal protein distribution within cells or tissues. For purification, immunoaffinity chromatography uses immobilized antibodies to capture targets from mixtures. For catalysis, antibodies raised against transition-state analogs can catalyze reactions by preferentially binding transition-state-like structures.

Step-by-Step Solution:
A: Use fluorescent or enzyme-conjugated antibodies to visualize proteins.B: Couple antibody to resin; bind and elute target protein.C: Generate abzymes via transition-state analog immunization; test catalytic rate enhancement.

Verification / Alternative check:
Common kits (IHC/IF, IP/Co-IP, immunoaffinity columns) and literature on abzymes validate these uses.

Why Other Options Are Wrong:

• None of the above: Contradicts standard lab practice and research applications.

Common Pitfalls:
Overlooking antibody orientation and elution conditions in purification; misinterpreting nonspecific staining without proper controls.

Final Answer:
All of the above.