Final answer:
Enzyme antibodies are highly flexible in Western blot detection due to their ability to bind various epitopes and their enzymatic signal amplification, which enhances both sensitivity and specificity of the assay, allowing detection of low antigen levels.
Step-by-step explanation:
Enzyme antibodies offer the most flexibility in detection for Western blotting due to their ability to bind different epitopes of an antigen and amplify the signal via an enzymatic reaction. In Western blot assays, typically polyclonal antibodies are used because they are more sensitive than monoclonal antibodies (mAbs) owing to their capability to recognize multiple epitopes. This leads to a stronger signal. Monoclonal antibodies, while specific to a single epitope, may not provide as strong of a signal due to this specificity. However, in enzyme-linked immunosorbent assays (ELISAs), enzyme-antibody conjugates are used to visualize or quantify antigens with a high degree of specificity, and they can be used to measure the presence of antigens within a range as low as nanograms per milliliter.
Western blotting uses a layered approach where the target protein is first bound by a primary antibody and then a secondary antibody coupled to an enzyme, such as alkaline phosphatase, binds to the primary antibody. The substrate for the enzyme produces a color change or a fluorescence signal, allowing precise detection. The enzyme acts as a signal amplifier, which means even low levels of an antigen can produce a detectable signal, thus enhancing sensitivity and specificity of the assay.