Which assay is described as a homogeneous enzyme immunoassay?

Which assay is described as a homogeneous enzyme immunoassay?

• A. Chemiluminescence immunoassay
• B. Enzyme-multiplied immunoassay technique
• C. Fluorescent polarization immunoassay
• D. High-performance liquid chromatography

Answer: (B)

A homogeneous enzyme immunoassay is one where the signal is generated entirely in solution, without any separation step to wash away unbound reagents. In this approach, an enzyme-labeled antigen competes with the unlabeled analyte for antibody binding. When the antibody binds to the enzyme-labeled antigen, the enzyme activity is inhibited; when the analyte is present, it reduces this inhibition, leaving more active enzyme in solution. Measuring the enzyme activity directly in the mixture provides a readout proportional to the analyte concentration, and because everything happens in one phase, no washing is required. This is why the enzyme-multiplied immunoassay technique is the best example: it relies on an enzyme label and a competitive setup that yields a signal in the reaction mixture itself, fulfilling the homogeneous format. The other options involve different readouts or methodologies (chemiluminescence without necessarily relying on an enzyme in the same way, fluorescent polarization, or a chromatographic method), so they don’t describe the homogeneous enzyme immunoassay in question.

A homogeneous enzyme immunoassay is one where the signal is generated entirely in solution, without any separation step to wash away unbound reagents. In this approach, an enzyme-labeled antigen competes with the unlabeled analyte for antibody binding. When the antibody binds to the enzyme-labeled antigen, the enzyme activity is inhibited; when the analyte is present, it reduces this inhibition, leaving more active enzyme in solution. Measuring the enzyme activity directly in the mixture provides a readout proportional to the analyte concentration, and because everything happens in one phase, no washing is required.

This is why the enzyme-multiplied immunoassay technique is the best example: it relies on an enzyme label and a competitive setup that yields a signal in the reaction mixture itself, fulfilling the homogeneous format. The other options involve different readouts or methodologies (chemiluminescence without necessarily relying on an enzyme in the same way, fluorescent polarization, or a chromatographic method), so they don’t describe the homogeneous enzyme immunoassay in question.