The enzyme horseradish peroxidase， found in horseradish， is used extensively in molecular biologyand in antibody amplification and detection， among other things. For example， "In recent years the technique of marking neurons with the enzyme horseradish peroxidase（HRP) has become a major tool. In its brief history， this method has probably been used by more neurobiologists than have used the Golgi stainsince its discovery in 1870." Horseradish peroxidase is also highly used in techniques such as Western blottingand ELISAs.
HRP is widely used as an enzymatic label in immunoassays. Usually， the enzyme is coupled to antibodies， lectins or haptens. Coupling to antibodies etc. may be performed through the carbohydrate side chains of the HRP.
