Zinc Content of Promatrilysin, Matrilysin and the Stromelysin Catalytic Domain

Abstract Promatrilysin expressed in Escherichia coli and Chinese hamster ovary cells contains 2.36 ± 0.19 and 2.13 ± 0.39 moles of zinc per mole of protein, respectively, while the activated enzyme contains 2.22 ± 0.21. The catalytic domain of stromelysin-1 expressed in E. coli contains 2.22 ± 0.11. Thus these matrix metalloproteinases contain two metal binding sites at which zinc is bound firmly and possibly a third site at which it is bound weakly. Promatrilysin and matrilysin do not contain significant amounts of Fe, Cu, Mn, or Ni. All known matrix metalloproteinases have a sequence homologous to the zinc binding site of astacin, HExxHxxGxxH , suggesting that one of the zinc sites is catalytic in agreement with the known inhibition of these enzymes by chelators.