[Skin high-molecular-weight protease. 2. Biochemical properties].

The purification of High-Molecular-Weight Protease from Wistar Rat's skin was previously investigated and reported. Some properties of this enzyme were subsequently investigated. This enzyme showed high activities toward succynyl-leucyl-leucyl-valyl-tyrosine-methylcoumarinamide (SLLVT-MCA). The addition of 0.03% sodium dodecyl sulphate (SDS) stimulated enzyme activity to 2,000% of the initial activity. The pH optimum was pH 8.5 in the presence of 0.03% SDS, but pH 6.0-8.5 in the absence of SDS. This enzyme was inhibited by one of serine protease inhibitors, diisopropylfluorophosphate (DFP) strongly. It was also inhibited by some of SH protease inhibitors, N-ethylmaleimide (NEM), iodoacetamide (IA), and leupeptin. Interestingly, chymostatin, a serine and SH protease inhibitor also inhibited enzyme activity. These results show that both serine and cysteine++ residues are related to the enzyme activity of High-Molecular-Weight Protease.