Ionic channels in Langmuir-Blodgett films imaged by a scanning tunneling microscope.
The molecular structure of channels formed by gramicidin A in a lipid membrane was imaged by a scanning tunneling microscope operating in air. The mono- and bimolecular films of lipid with gramicidin A were deposited onto a highly oriented pyrolitic graphite substrate by the Langmuir-Blodgett technique. It has been shown that under high concentration gramicidin A molecules can form in lipid films a quasi-regular, densely packed structure. Single gramicidin A molecules were imaged for the first time as well. The cavity of 0.4 +/- 0.05 nm in halfwidth was found on the scanning tunneling microscopy image of the gramicidin A molecule. The results of direct observation obtained by means of scanning tunneling microscope are in good agreement with the known molecular model of gramicidin A. It was shown that gramicidin A molecules can exist in a lipid monolayer as individual molecules or combined into clusters. The results demonstrate that scanning tunneling microscope can be used for high spatial resolution study of ionic channel structure.
Kolomytkin
O V
OV
Institute of Biophysics, Academy of Sciences of the USSR, Pushchino.
Golubok
A O
AO
Davydov
D N
DN
Timofeev
V A
VA
Vinogradova
S A
SA
Tipisev SYa
D015060:1,2-Dipalmitoylphosphatidylcholine / Q000737:chemistry; D005989:Glycerides; D006096:Gramicidin / Q000737:chemistry*; D007473:Ion Channels; D008051:Lipid Bilayers; D016252:Microscopy, Scanning Tunneling / Q000379:methods; D008954:Models, Biological; D008958:Models, Molecular; D008968:Molecular Conformation; D011487:Protein Conformation
D005989:Glycerides; D007473:Ion Channels; D008051:Lipid Bilayers; D006096:Gramicidin; D015060:1,2-Dipalmitoylphosphatidylcholine; C005953:monoolein