title: Tuning the self-assembly of the bioactive dipeptide L-carnosine by incorporation of a bulky aromatic substituent.
abstract: The dipeptide L-carnosine has a number of important biological properties. Here, we explore the effect of attachment of a bulky hydrophobic aromatic unit, Fmoc [N-(fluorenyl-9-methoxycarbonyl)] on the self-assembly of Fmoc-L-carnosine, i.e., Fmoc-β-alanine-histidine (Fmoc-βAH). It is shown that Fmoc-βAH forms well-defined amyloid fibrils containing β sheets above a critical aggregation concentration, which is determined from pyrene and ThT fluorescence experiments. Twisted fibrils were imaged by cryogenic transmission electron microscopy. The zinc-binding properties of Fmoc-βAH were investigated by FTIR and Raman spectroscopy since the formation of metal ion complexes with the histidine residue in carnosine is well-known, and important to its biological roles. Observed changes in the spectra may reflect differences in the packing of the Fmoc-dipeptides due to electrostatic interactions. Cryo-TEM shows that this leads to changes in the fibril morphology. Hydrogelation is also induced by addition of an appropriate concentration of zinc ions. Our work shows that the Fmoc motif can be employed to drive the self-assembly of carnosine into amyloid fibrils.
authors.affiliation: School of Chemistry, Food Science and Pharmacy, University of Reading, Whiteknights, Reading RG6 6AD, United Kingdom.
authors.forename: V
authors.initials: V
authors.lastname: Castelletto
authors.forename: G
authors.initials: G
authors.lastname: Cheng
authors.forename: B W
authors.initials: BW
authors.lastname: Greenland
authors.forename: I W
authors.initials: IW
authors.lastname: Hamley
authors.forename: P J F
authors.initials: PJ
authors.lastname: Harris
mesh_terms: D002336:Carnosine / Q000737:chemistry*; D005449:Fluorenes / Q000737:chemistry*; D057927:Hydrophobic and Hydrophilic Interactions; D015394:Molecular Structure; D010316:Particle Size; D013499:Surface Properties
chemical_list: C496789:9-fluorenylmethoxycarbonyl; D005449:Fluorenes; D002336:Carnosine