Influence of acylation on the channel characteristics of gramicidin A.

The influence of acylation on the conductance, average duration, and channel-forming potency of channels formed by gramicidin A analogues was investigated using single-channel and multichannel techniques. Lauroyl-, myristoyl-, palmitoyl-, stearoyl-, and oleoylgramicidin A were prepared by covalent coupling of that fatty acid to the C-terminal ethanolamine group. Acylation of gramicidin A does not affect the single-channel conductance or the minichannel frequency in diphytanoylphosphatidylcholine/n-decane black lipid membranes. However, the average duration of all acylgramicidin channels was increased approximately 5-fold as compared to unmodified gramicidin A, which has a duration of 0.9 s at 200-mV applied potential. Somewhat surprisingly the rate of channel formation of the acylgramicidins is decreased relative to gramicidin A: lauroyl- and stearoylgramicidin are approximately 200 times less effective in channel formation as compared to gramicidin A. We conclude that channels formed by the acylgramicidins and by gramicidin A are structurally and conformationally equivalent.

[1]  L. B. Weiss,et al.  Single-channel studies on linear gramicidins with altered amino acid side chains. Effects of altering the polarity of the side chain at position 1 in gramicidin A. , 1986, Biophysical journal.

[2]  O. Andersen,et al.  Energetics of gramicidin hybrid channel formation as a test for structural equivalence. Side-chain substitutions in the native sequence. , 1990, Journal of molecular biology.

[3]  H. Huang,et al.  Deformation free energy of bilayer membrane and its effect on gramicidin channel lifetime. , 1986, Biophysical journal.

[4]  C. Etchebest,et al.  The gramicidin A channel , 1984 .

[5]  M. Schmidt.  Fatty acylation of proteins , 1989, Biochimica et Biophysica Acta (BBA) - Reviews on Biomembranes.

[6]  E. Blout,et al.  Structural information from functional measurements: single-channel studies on gramicidin analogues. , 1986, Biophysical journal.

[7]  E. Jakobsson,et al.  Calculation of deformation energies and conformations in lipid membranes containing gramicidin channels. , 1990, Biophysical journal.

[8]  O. Andersen.  Ion movement through gramicidin A channels. Single-channel measurements at very high potentials. , 1983, Biophysical journal.

[9]  P. Watnick,et al.  Hydrophobic mismatch in gramicidin A'/lecithin systems. , 1990, Biochemistry.

[10]  R. Hochmuth,et al.  Analysis of lateral diffusion from a spherical cell surface to a tubular projection. , 1992, Biophysical journal.

[11]  R. Koeppe,et al.  Gramicidin K, a new linear channel-forming gramicidin from Bacillus brevis. , 1985, Biochemistry.

[12]  Lipid polymorphism and the functional roles of lipids in biological membranes. , 1979 .

[13]  C. Venkatachalam,et al.  Synthesis, characterization, and black lipid membrane studies of [7-L-alanine] gramicidin A. , 1986, Biochemistry.

[14]  B. Ninham,et al.  Theory of self-assembly of hydrocarbon amphiphiles into micelles and bilayers , 1976 .

[15]  S. Hladky,et al.  Ion Movements in Gramicidin Channels , 1984 .

[16]  B. de Kruijff,et al.  Synthesis of acylated gramicidins and the influence of acylation on the interfacial properties and conformational behavior of gramicidin A. , 1991, Biochimica et biophysica acta.

[17]  D. Sawyer,et al.  Induction of conductance heterogeneity in gramicidin channels. , 1989, Biochemistry.

[18]  C. Etchebest,et al.  Experimental and theoretical study of gramicidin P, an analog of gramicidin A with a methylamine C‐terminal , 1987, FEBS letters.

[19]  Urry Dw,et al.  The Gramicidin A Transmembrane Channel: A Proposed π(L,D) Helix , 1971 .

[20]  D. Mayers,et al.  The gramicidin A transmembrane channel: characteristics of head-to-head dimerized (L,D) helices. , 1971, Proceedings of the National Academy of Sciences of the United States of America.