Proteinase binding and enhancing factor from human skin.

Fresh human skin extract made in salt solution after a prior buffer extraction was shown to enhance the hydrolysis of N-alpha-benzoyl-DL-arginine beta-naphthylamide (BANA) by trypsin. This trypsin enhancing effect was further shown to be both stabilizing and activating. After chromatography on Sephadex G-100, the trypsin binding factor was found in fractions of void volume. Protease binding took place in physiological and hypotonic but not in hypertonic NaCl-solutions (0.5 mol/l). The proteinase binding factor was further purified by trypsin-Sepharose 4 B affinity chromatography. It was found to bind also chymotrypsin and elastase and to be thermostable (100 degrees C for 20 min), precipitable at acidic pH (3.5), and by acetone and ammonium sulphate (60% saturation). The bound proteinases were found to preserve their hydrolytic activity towards protein substrates. Bound trypsin and chymotrypsin could completely be inhibited by soybean trypsin inhibitor. The binding factor did not react with anti-human-alfa2-macroglobulin antiserum from rabbit.