Abstract
A novel zinc endoproteinase has been sequenced and characterized from soybean leaves (Glycine max var Williams 82) and has been designated as Protein Identification Resource accession No. A41820 SMEP1 (soybean metalloendoproteinase 1). Comparison of the primary amino acid sequence with other zinc proteinases revealed the enzyme to be a new member of the matrix metalloproteinase (MMP) family of enzymes. SMEP was found to have MMP cleavage specificity toward peptide substrates and the enzyme is specifically inhibited by naturally occurring tissue inhibitors of MMPs through a high-affinity interaction (inhibitor concentration resulting in an approximate 50% decrease in enzyme activity = 23 x 10(-9) molar). Together, these results suggest that the origin of the MMP family of enzymes and their cognate inhibitors predates the divergence of plants and animals.