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.
Vogt
T C
TC
Department of Biochemistry of Membranes, University of Utrecht, The Netherlands.
Killian
J A
JA
De Kruijff
B
B
Andersen
O S
OS
D000215:Acylation; D004553:Electric Conductivity; D006096:Gramicidin / Q000737:chemistry*; D007202:Indicators and Reagents; D007473:Ion Channels / Q000502:physiology*; D007700:Kinetics; D008051:Lipid Bilayers; D008433:Mathematics; D008954:Models, Biological; D013329:Structure-Activity Relationship
D007202:Indicators and Reagents; D007473:Ion Channels; D008051:Lipid Bilayers; D006096:Gramicidin