Direct comparison of enzyme histochemical and immunohistochemical methods to localize an enzyme

Immunohistochemical localization of enzymes is compared directly with localization of enzyme activity with (catalytic) enzyme histochemical methods. The two approaches demonstrate principally different aspects of an enzyme. The immunohistochemical method localizes the enzyme protein whether it is active or not whereas the catalytic method visualizes the functionally active enzyme only. Furthermore, enzyme histochemical methods appear to be highly sensitive in comparison with immunohistochemical methods. Finally, the catalytic methods are simple and last 5–60 min at room temp, whereas immunohistochemical methods take hours at least. It can be concluded that enzyme histochemical methods are the methods of choice to localize enzymes because they detect the functional activity of an enzyme, they are relatively simple and their sensitivity is high.