ABSTRACT
INTRODUCTION: Matrix metalloproteinase-20 (MMP-20) is a predominant enzyme for the progressive processing of enamel extracellular matrix protein components (primarily amelogenin) during the early stages of enamel formation. So far, the recombinant porcine, mouse and bovine MMP-20 have been cloned and used extensively in the researches of tooth enamel development. The homology of these MMP-20s to human MMP-20 is approximately 80%. The effect of sequence differences on the properties of these enzymes is poorly understood even though they have been used to hydrolyse amelogenins from different species. OBJECTIVE: Our goal is to compare the characteristics between recombinant human MMP-20 (rhMMP-20) and bovine MMP-20 (rbMMP-20). DESIGN: rhMMP-20 and rbMMP-20 were parallelly expressed, purified and activated. The SDS-PAGE, zymography and quenched peptide assay were used for characterization and comparisons. RESULTS: Both proteases were activated by autocatalysis in a similar pattern of fragmentation. Dynamically, rbMMP-20 autoactivated faster and digested a fluorescence-quenched peptide Mca-PLGL-Dpa-AR, a non-amelogenin substrate, more efficiently than rhMMP-20. However, rhMMP-20 showed higher enzymatic activity for a human amelogenin substrate and in addition, it created an extra cleavage site at its C-terminus. CONCLUSIONS: The differences in their catalytic properties and substrate specificities may be attributed to the sequence divergence of MMP-20 between species, especially in the hinge region.
