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[Ala4]Surfactin, a Novel Isoform from Bacillus subtilis Studied by Mass and NMR Spectroscopies
Abstract
When Bacillus subtilis S 499 was grown on a culture medium containing L-alanine as nitrogen source, a mixture of surfactins was obtained. Suitable chromatographic conditions allowed the separation of isoforms. Among these compounds, a new variant of surfactin was isolated and its structure was established by chemical and spectrometric methods, especially by NMR spectrometry. It contains a peptide sequence which differs from that of standard surfactin by the replacement of the L-valine residue by L-alanine residue in position 4. The folding mode of [Ala4]surfactin as deduced from NMR results was compared with that of standard surfactin and the structure/properties relationship issuing from the study of this new isoform is discussed.
Abbreviations
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- [Ala4]Surfactin
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- surfactin in which Val4 has been replaced by Ala
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- LSIMS
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- liquid secondary ion mass spectrometry
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- DQF-COSY
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- double-quantum-filter correlation spectroscopy
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- TOCSY
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- total correlation spectroscopy
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- NOESY
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- nuclear Overhauser enhancement spectroscopy
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- γCMC
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- surface tension close to the critical micellar concentration