Abstract
Summary
A method of controlled inactivation of alkaline phosphatase in tissue sections by removal of the activating metallic component through chelation is described. The enzyme activity of alcohol-fixed, paraffin-embedded rabbit kidney can be completely inhibited by EDTA and subsequently reactivated by a variety of metallic cations in 0.1 molar concentration, including Mg++, Co++, Zn++, Ca++, Sr++ and Ba++. Ni++ is a weak reactivator. The localization of enzyme activity in the tissue is the same regardless of the reactivating ion. Hg++, Be++, and Cu++ are constant strong inhibitors. Mn++, Pb ++ and Cd++ fail to reverse EDTA inhibition but will not themselves inhibit the active enzyme in the concentrations used. Preliminary experiments indicate, however, that the alkaline phosphatase of guinea pig and monkey kidney is inhibited by Pb++ and Cd++ in much lower concentrations.
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