Micellization activity of the natural lipopeptide [Glu1, Asp5] surfactin-C15 in aqueous solution.
Surface tension, small angle neutron scattering (SANS), freeze-fracture transmission electron microscopy (FF-TEM), and circular dichroism (CD) have been used to study the self-aggregation properties of the natural lipopeptide [Glu(1), Asp(5)] surfactin-C15 in 0.01 M phosphate buffer solution (PBS) at pH 7.4. It has been found that the critical micelle concentration (cmc) of surfactin is 1.54 x 10(-5) M, the surface tension at the cmc (sigma(cmc)) is 27.7 mN/m, and the area per molecule at the air-water interface is 107.8 A(2). Surfactin molecules adopt a beta-sheet conformation already at low concentrations. This feature probably makes it surface-active at such low concentrations. From SANS and FF-TEM results, it is seen that surfactin exhibits a strong self-assembly ability to form sphere-like micelles and some larger aggregates even at the rare low concentration. The aggregation number of sphere-like micelles is much smaller than that for conventional surfactants of similar alkyl chain length.
Zou
Aihua
A
State Key Laboratory of Bioreactor Engineering and Institute of Applied Chemistry, East China University of Science and Technology, Shanghai 200237, PR China.
Liu
Jing
J
Garamus
Vasil M
VM
Yang
Ying
Y
Willumeit
Regine
R
Mu
Bozhong
B
D000388:Air; D002942:Circular Dichroism; D055666:Lipopeptides / Q000737:chemistry*; D008823:Micelles; D046529:Microscopy, Electron, Transmission; D010316:Particle Size; D010456:Peptides, Cyclic / Q000737:chemistry*; D011487:Protein Conformation; D053838:Scattering, Small Angle; D012996:Solutions; D013500:Surface Tension; D014867:Water / Q000737:chemistry
D055666:Lipopeptides; D008823:Micelles; D010456:Peptides, Cyclic; D012996:Solutions; D014867:Water; C009365:surfactin peptide