Determination of ion permeability through the channels made of porins from the outer membrane of Salmonella typhimurium in lipid bilayer membranes.

摘要: The three types of porin (matrix-proteins) fromSalmonella typhimurium with molecular weights 38,000, 39,000 and 40,000 were reconstituted lipid bilayer membranes either as a trimer or an oligomer (complex I). specific conductance the increased several orders magnitude after addition porins into aqueous phase bathing membranes. A linear relationship between protein concentration in membrane was found. In case lower concentrations (10−12m), stepwise fashion single increment 2.3 nS 1m KCl. For given salt found to be largely independent particular (38 K, 39K 40 K) on state aggregation, although oligomers showed up 10 times smaller increase macroscopic measurements. pathway has ohmic current voltage characteristic poor selectivity for different alkali ions. Further information structure pores formed by obtained from various From permeability pore large ions (Tris+, glucosamine+, Hepes−_ minimum diameter 0.8 nm is estimated. This value agreement size calculated data KCl (1.4 length 7.5 nm). may well account sugar which been vesicles. findings reported here are consistent assumption that form channels condutance unit trimer. addition, it suggested one contains only rather than bundle pores.