What type of assays measure the reaction of protein and antibody?

The correct answer is immunochemical assays. These assays are specifically designed to measure interactions involving antibodies and antigens, which are typically proteins. Immunochemical assays utilize the specificity of antibodies to bind to their target antigens, allowing for the detection and quantification of proteins present in various samples, such as serum or tissue extracts.

Immunochemical techniques include a range of methods, such as enzyme-linked immunosorbent assays (ELISAs), Western blots, and radioimmunoassays, all of which capitalize on the specificity of antibody-antigen interactions. By measuring these reactions, immunochemical assays provide valuable information about the presence, quantity, and sometimes the function of proteins, which is essential in diagnostics, research, and therapeutic monitoring.

Serological assays, while related, are broader in scope and refer specifically to tests that detect antibodies or antigens in serum, which may include immunochemical techniques but do not solely measure the reactions of proteins and antibodies. Chemical assays generally involve the identification or quantification of chemical compounds and do not focus on the specific interactions between proteins and antibodies. Molecular assays are used to analyze nucleic acids (DNA or RNA) rather than proteins or their interactions, thus falling outside the context of measuring protein-antibody reactions.