A Molecular Theory of Ion-Conducting Channels: A Field-Dependent Transition Between Conducting and Nonconducting Conformations

摘要: Abstract Structural and conformational requirements for an electric field-dependent transition between conducting nonconducting macromolecular systems are: two kinetically interconvertible energetically similar conformations, one the other nonconducting, which have axes spanning lipid layer of biological membranes, but different net dipole moments along those axes. Two examples are described. A previously defined helix, π6LD-helix now termed β63,3-helix, is proposed as species, linear peptide correlate cyclic hexapeptide conformation containing β-turns inversion element symmetry a species. The latter anti-β62-spiral contains little or no moment per turn, whereas β63,3-helix helix axis about 0.5 Debye dipeptide unit. related pair with large opposite sign, syn-β62-spiral β62,4-helix, also spiral conformations stabilized in by intermolecular hydrogen bonds, leading to association transmembrane structures. member array could lead destabilization adjacent array. analysis uses concept correlates. derivable from structure [unk], syn-β2-spiral β62,4-helix may be derived [unk]. The leads expectation that N-formyl-(L-Ala-L-Ala-Gly)n would form channels.