Modified and Mutant Porins in the Study on Molecular Basis of Non- Specific Diffusion.

Site-directed mutagenesis allows elucidation of the basic principles of the porin-driven membrane permeability and opens the possibility for the modulation of functional states of porin channels. The review is aimed to show the advantages of using mutant and chemically modified porins for obtaining detailed information about molecular mechanisms that underlie the non-specific transmembrane diffusion. We summarized data regarding the effects of the point substitutions and the external loop deletions on electrophysiological properties of general porins. The influence of charges inside the pore eyelet and the roles of external loops in ion conductance, ion selectivity, and voltage gating were described.