FIBRINO(GENO)LYTIC PROPERTIES OF PURIFIED HEMENTERIN, A METALLOPROTEINASE FROM THE LEECH HAEMENTERIA-DEPRESSA

The fibrino(geno)lytic protein designated hementerin contained in crud e extracts of the salivary complex of Haementeria depressa leeches was purified to apparent homogeneity by gel filtration, ion exchange chro matography and preparative SDS-PAGE. It is a single-chain 80 kDa, PhMe SO2F-resistant, calcium-dependent, metalloproteinase, which specifical ly degrades fibrin(ogen) through a plasminogen-independent pathway. Th e amino terminal sequence of 8 residues shows 80% similarity with heme ntin, another fibrino(geno)lytic protein purified from Haementeria ghi lianii leeches. However, their activities differ somewhat in terms of kinetics and with regard to the structure of the fibrin(ogen) fragment s they may produce. Cleavage by hementerin of fibrinogen A alpha, gamm a and B beta chains, in that order, produces 270 kDa to 67 kDa fragmen ts which differ from those produced by plasmin. Hementerin was also ab le to degrade cross-linked fibrin although at a lower rate as compared to fibrinogen. In conclusion, hementerin is a plasminogen-independent fibrino(geno)lytic metalloproteinase that degrades fibrinogen faster than fibrin, prevents blood coagulation and destroys fibrin clots in v itro.