Soluble metalloendopeptidase (MMP-7ase) activity in mouse kidney cytosol.

Previously, MMP-7ases were isolated from rat skeletal muscle by gel filtration and anion exchange chromatography. The enzyme that hydrolyzed succinyl-Ala-Ala-Pro-Phe-AMC (AMC: 7-amino-4-methyl-coumarin) was inhibited by EDTA. In this study we attempted to isolate MMP-7ase from mouse kidney. The isolation procedure was the same as that previously used for skeletal muscle. Kidneys of ICR mice were homogenized and, after centrifugation, the supernatant fraction was subjected to gel filtration chromatography. The fraction with the highest activity (Mr 67-72 kDa) was subjected to anion exchange chromatography, which showed three peaks of activity. The second peak hydrolyzed succ-Ala-Ala-Pro-Phe-AMC, but had low activity against Arg- or Ala-AMC. This peak was a single protein (Mr 68-72 kDa) and its activity could be inhibited with EDTA. Several tri- and tetrapeptide derivatives were tested as substrates for this enzyme and the best was found to be succ-Ala-Ala-Pro-Phe-AMC. We can conclude that mouse kidney cytosol contains a metalloendopeptidase similar to muscle MMP-7ase.