ISSN:
1075-2617
Keywords:
peptide surfactant
;
surfactin
;
conformation
;
micelles
;
biosurfactant
;
Chemistry
;
Biochemistry and Biotechnology
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
We have studied the effects of extrinsic environmental conditions on the conformation of surfactin, a heptapeptide biosurfactant from Bacillus subtilis, in aqueous solutions. It has been made clear that temperature, pH, Ca2+ ions and the synthetic nonionic surfactant hepta-ethylene glycol (C12E7) affect the conformation of surfactin in aqueous solutions. The β-sheet formation reached a maximum at 40°C both in presence and absence of (C12E7) and the nonionic surfactant enhances the β-sheet formation even at 25°C. Ca2+ induced the formation of a-helices and caused this transition at 0.3 mm with surfactin monomers or at 0.5 mm with surfactin micelles, but above these transition concentrations of Ca2+ β-sheets were observed. In micellar solution the β-sheet structure was stabilized at pH values below 7 or upon addition of Ca2+ in concentrations above 0.5 mm. Our results indicated that the bioactive conformation of surfactin is most likely the β-sheets when the molecules are assembled in micelles. The β-sheet structure in micelles could be retained by tuning the micelles. Surfactin micelles could be tuned in the bioactive conformation by manipulating pH, temperature, Ca2+ or (C12E7) concentrations in surfactin solutions. Our results strongly indicated that Ca2+ and other molecules (such as C12E7) may function as directing templates in the assembly and conformation of surfactin in micelles. Thus, we suggest environmental manipulation and template-aided micellation (TAM) as a new approach for preparing predesigned micelles, microemulsions or micro-spheres for specific application purposes. © 1998 European Peptide Society and John Wiley & Sons, Ltd.
Additional Material:
3 Ill.
Type of Medium:
Electronic Resource
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