Structural and functional zinc in horse liver alcohol dehydrogenase.

Abstract

Horse liver alcohol dehydrogenase containing 3.4-3.6 gm at. of Zn/mol. wt. 80,000, dissociates into 2 subunits in 8 [image] urea and further into 4 subunits of mol. wt. 20,000 upon removal of a fraction of the Zn content. Two Zn atoms are essential for activity, "free" and accessible to the ambient medium as gauged by their reactivity toward certain chelating agents and by isotope exchange. They do not appear to participate in subunit interactions. The balance are un-reactive or "buried" but participate in forming the quaternary structure of the enzyme. The relationship of Zn content, reactivity, and modes of interaction with subunit and isoenzyme structure is discussed.