Controlling morphology of peptide-based soft structures by covalent modifications

Control of gross morphology of soft matter remains an area of continued interest. Towards this goal, this paper describes conjugation of mannose residues and introduction of thiol functionalities to diphenylalanine (FF) dipeptide, a fibrillating motif from amyloid-beta peptide, as covalent modifiers of its solution-phase self-assembly process. It was found that covalent attachment of a single mannose residue to FF leads to the retention of tubular structures, whereas the conjugation of two mannose units, linked through a Lys residue, resulted in a dramatic change from tubular morphology to spherical structures. However, a similar switch to spherical objects could be achieved by introducing a thiol residue in the mono-mannosylated FF dipeptide. Interestingly, these glycopeptides also exhibited interaction with concanavalin A, thereby providing an indirect evidence for the availability of mannose units for the process of lectin-carbohydrate interaction in the self-organized state. Copyright (c) 2012 European Peptide Society and John Wiley & Sons, Ltd.