| Abstract
| - 13C-Labeled amphotericin B (AmB) was prepared by feeding the producing organismStreptomyces nodosus with [3-13C]propionate. The REDOR experiments for dimyristoylphosphatidylcholine(DMPC) membrane using the 13C-labeled AmB showed the prominent dephasing effects between thephosphate group in PC and C41 carboxyl carbon in the polar head. In addition, C39/C40 methyl carbonsalso gave rise to the significant reduction of their 13C NMR signals, implying that both terminal parts ofAmB reside close to the surface of the DMPC membrane. Conversely, the same REDOR experimentswith use of distearoylphosphatidylcholine (DSPC) showed no dephasing for the C39/C40 methyl signalswhile a marked reduction of the C41 carbonyl signal was again observed. These findings should be mostreasonably accounted for by the notion that AmB can span across the DMPC membrane with a single-length interaction but cannot span the DSPC membrane due to its greater thickness. To our knowledge,the results provide the first direct spectroscopic evidence for the formation of a single-length channelacross a biomembrane, which was previously suggested by channel current recording experiments.
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