A protease-like permeability factor in the guinea pig skin. 2. In vitro activation of the latent form permeability factor by weakly acidic phosphate buffer.

Conditions for the in vitro activation of the latent form of a protease-like permeability factor in the pseudoglobulin fraction from guinea pig skin were examined. (1) The factor was activated by dialysis against 67 mM phosphate buffer at pH 5.8--6.4, not at pH 7.0--8.0. (2) High salt concentration (200 mM or greater phosphate buffer or 67 mM phosphate buffer containing 200 mM or greater KCl or NaCl) prevented the activation at pH 6.2. (3) High osmotic pressure (sucrose at 1 M) did not affect activation at pH 6.2. (4) Reconversion of the activated permeability factor into an inactive form was not observed under high salt conditions, under which the latent permeability factor was stable in its own form. (5) The molecular size of the latent permeability factor was estimated as approx. 80 000 by Sephadex G-100 gel filtration at high salt concentration.