In EMIT, the enzyme is coupled to which molecule?

In EMIT, the enzyme is coupled to which molecule?

• A. Antibody
• B. Antigen
• C. Substrate
• D. Coenzyme

Answer: (B)

In EMIT, the labeled component that provides the measurable signal is created by attaching the enzyme to the antigen. This enzyme-labeled antigen acts as the tracer in a competitive immunoassay: the antibody binds either the patient’s free antigen or the enzyme-labeled antigen, and the enzyme’s activity is affected by this binding. Because binding to the antibody inhibits the enzyme, the amount of signal you detect depends on how much antibody is bound to the labeled tracer versus the free antigen. The key point is that the enzyme is chemically linked to the antigen, not to the antibody, substrate, or coenzyme. This is why the molecule coupled to the enzyme is the antigen.

In EMIT, the labeled component that provides the measurable signal is created by attaching the enzyme to the antigen. This enzyme-labeled antigen acts as the tracer in a competitive immunoassay: the antibody binds either the patient’s free antigen or the enzyme-labeled antigen, and the enzyme’s activity is affected by this binding. Because binding to the antibody inhibits the enzyme, the amount of signal you detect depends on how much antibody is bound to the labeled tracer versus the free antigen. The key point is that the enzyme is chemically linked to the antigen, not to the antibody, substrate, or coenzyme. This is why the molecule coupled to the enzyme is the antigen.