 The inhibitor binds to the zinc at the active center of the enzyme, thereby blocking its activity.Other inhibitor mechanisms are possible.α2-Macroglobulin (α2M) is a protease inhibitor which inhibits activated MMPs.α2M and MMP form a complex which is able to inactivate the MMP.MMPs are associated with the cell surface or bound to the extracellular matrix which prevents them from diffusing away and keeps the MMP under control of the cell.