Pure protein was obtained by solubilization of the red precipitate
that was formed in the fraction eluted with 10 mM Tris–HCl
using 10 mM potassium phosphate buffer and 100 mM KCl. To prevent
protein precipitation 0.05% of DDM was added to the solubilized
solution. Since the periplasmic space of Gram-positive
bacteria is narrower than that of Gram-negative bacteria and
crossed by several membrane bound polymers