Département de chimie moléculaire

Amphiphilic catechol-type iron chelators were studied with the aim of mimicking the properties of marine bacterials siderophores. The FeIII complexation consts. and aq. soln. speciation of LS10, a sulfonated catechol unit that has a C10 lipophilic carbon chain connected by an amide linkage, were detd. by spectro-photometric titrn. The calcd. value of pFe3+ is 18.1 at pH 7.4. Cryogenic TEM showed that the tris(catecholate) ferric complex formed at physiol. pH initially assembles into micelles, in which the catecholate-iron units stay on the exterior of the micelle. The av. diam. of these micelles was estd. to be 4.2 nm. The micelles then slowly rearrange into clusters of different sizes, which leads to the formation of unilamellar and bilamellar vesicles. The reorganization processes are comparable to those obsd. by Butler et al. for the marinobactin siderophores produced by marine bacteria, but in contrast to the marinobactins, vesicles of the Fe3+ - LS10 complex form without an excess of iron relative to ligand concn. The time-dependent micelle-to-vesicle transition is discussed herein. [on SciFinder(R)]