ZINC CONTENT OF PROMATRILYSIN, MATRILYSIN AND THE STROMELYSIN CATALYTIC DOMAIN

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 p rotein, 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 bin ding sites at which zinc is bound firmly and possibly a third site at which it is bound weakly. Promatrilysin acid matrilysin do not contain significant amounts of Fe, Cu, Mn, or Ni. All known matrix metallopro teinases have a sequence homologous to the zinc binding site of astaci n, HExxHxxGxxH,, suggesting that one of the zinc sites is catalytic in agreement with the known inhibition of these enzymes by chelators. (C ) 1994 Academic Press, Inc.