Purification and characterization of a connective-tissue-degrading metalloproteinase from the cytosol of metastatic melanoma cells

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Abstract
A metalloproteinase with activity against type IV collagen, type I collagen and gelatin has been purified from the cytosol of a highly metastatic mouse melanoma by anion-exchange, zinc-chelated and lectin-affinity column chromatography. The purified enzyme has a molecular mass of approx. 59 kDa and on isoelectric focusing in two-dimensional gels produced three spots with apparent isoelectric points (pI) between 5.7 and 6.1. Enzymic activity with collagen, but not gelatin, substrates was latent, requiring activation by trypsin or organomercurials. Trypsin activation of this metalloproteinase was accompanied by a change in molecular mass, whereas autoactivation after 1 month's storage, was not. The degradation of types I and IV collagen by the melanoma enzyme yielded products of lower molecular masses than those yielded by mammalian collagenases, this characteristic thus differentiating this metalloproteinase from classical collagenases.