Gramicidins A, B, and C form structurally equivalent ion channels Academic Article Article uri icon

Overview

MeSH Major

  • Gramicidin
  • Lipid Bilayers
  • Membrane Transport Proteins

abstract

  • The membrane structure of the naturally occurring gramicidins A, B, and C was investigated using circular dichroism (CD) spectroscopy and single-channel recording techniques. All three gramicidins form channels with fairly similar properties (Bamberg, E., K. Noda, E. Gross, and P. Läuger. 1976. Biochim. Biophys. Acta. 419:223-228.). When incorporated into lysophosphatidylcholine micelles, however, the CD spectrum of gramicidin B is different from that of gramicidin A or C (cf. Prasad, K. U., T. L. Trapane, D. Busath, G. Szabo, and D. W. Urry. 1983. Int. J. Pept. Protein Res. 22:341-347.). The structural identity of the channels formed by gramicidin B has, therefore, been uncertain. We find that when gramicidins A and B are incorporated into dipalmitoylphosphatidylcholine vesicles, their CD spectra are fairly similar, suggesting that the two channel structures could be similar. In planar bilayers, gramicidins A, B, and C all form hybrid channels with each other. The properties of the hybrid channels are intermediate to those of the symmetric channels, and the appearance rates of the hybrid channels (relative to the symmetric channels) corresponds to what would be predicted if all three gramicidin molecules were to form structurally equivalent channels. These results allow us to interpret the different behavior of channels formed by the three gramicidins solely on the basis of the amino acid substitution at position 11.

publication date

  • November 14, 1990

Research

keywords

  • Academic Article

Identity

PubMed ID

  • 1705449

Additional Document Info

start page

  • 1207

end page

  • 12

volume

  • 58

number

  • 5