HistoZyme is a proteolytic enzyme solution that results in superior staining over traditionally used enzyme pretreatments, such as pepsin and trypsin. Moreover, HistoZyme requires only a brief incubation at room temperature. Performing antigen recovery with HistoZyme, will allow you to dilute the primary antibody 5 to 10 fold further and achieve optimal staining.
Formalin fixation of tissues induces protein cross links that helps in maintaining the cellular morphology by inactivating the digestive enzymes and preserving the cytoskeleton. Fixation stops tissue autolysis, preserves tissue structures, and immobilizes antigens. However, antigens undergo chemical alteration of their primary, secondary and tertiary structures during fixation. This may cause a loss of reactivity of a specific antibody to that antigen. High-energy treatment of such proteins in appropriate pH leads to restoration of the epitope structure and hence retrieves the reactivity of antibody to the target antigen. This process is defined as Antigen Retrieval. Shi et al 1991. It has been suggested that antigen retrieval loosens or breaks the cross linkages induced by formalin. This allows for the enhanced penetration of antibodies and accessibility of epitopes.