Comparative properties of recombinant human and bovine matrix metalloproteinase-20

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.

Our goal is to compare the characteristics between recombinant human MMP-20 (rhMMP-20) and bovine MMP-20 (rbMMP-20).

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.

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.

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.