A Serine Proteinase from Cow Snout Epidermis Degrades High Molecular Weight Keratins

Abstract

This study describes a serine proteinase which degrades high molecular weight polypeptides of keratins. The enzyme was coextracted with 8M urea together with keratins and separated from the keratins by gel filtration chromatography. Molecular weight of the enzyme was estimated at 25,000 daltons by gel filtration. Revealed characteristics of the enzyme were as follows; 1) maximally active at pH 8.5-9.0, 2) requires 0.04% SDS for maximum activity, 3) heat stable in the absence of SDS up to 65°C for 2 min, 4) sensitive against serine protease inhibitor, phenylmethanesulfonyl fluoride and soybean trypsin inhibitor, 5) highly specific for natural protein substrates, such as keratin polypeptides.