Micelle to fibre biocatalytic supramolecular transformation of an aromatic peptide amphiphile

Abstract

We use a range of spectroscopic methods to provide mechanistic insight into a phosphatase-driven supramolecular transformation whereby an amphiphilic peptide building block, upon dephosphorylation, switches from a solution-phase, micellar structure to a gel-phase, chiral uni-directional nanofibre morphology.

Enzymatically activated emulsions stabilised by interfacial nanofibre networks

“…Having established the ability of the enzyme to trigger the self-assembly process, the second part of the study is to investigate the on-demand Figure 2b) that resulted in a hydrogel. Similar observations have been reported using Fmoc-Yp, 26,37 Fmoc-Phenylalanine-Yp (Fmoc-FYp), 18,27 Fmoc-FpY, 28 Fmoc-Yp-Serine (Fmoc-YpS) and The self-assembly process of aromatic peptide amphiphiles is known to be controlled by weak non-covalent hydrophobic interactions such as -stacking between fluorenyl groups and hydrogen bonding between amino acids. 20,21,38 Fluorescence spectroscopy spectra can provide evidence of aromatic interactions, since these may stabilize and form excimers which emit at agreement to what has been reported for Fmoc-Yp 37 and Fmoc-FpY.…”

“…The initial blue-shift probably occurs due to the disruption of stacking interactions when phosphate groups start to be cleaved, followed by a red-shift that points to a gradually formed fluorenyl stacking arrangement that gives rise to fibres as previously observed for the dephosphorylation of Fmoc-Yp. 39 The shoulder (peak at 375 nm), associated to micellar aggregates, 28,39,40 is only visible before the addition of alkaline phosphatase, which supports a micelle to fibre transition, by rearranging of the peptide chains and aromatic moieties upon dephosphorylation.…”

Nanopropulsion by Biocatalytic Self-Assembly

“…The amphiphilic nature of 1a results in formation of spherical micelle structures in water. 45 Enzymatic removal of the charged tyrosine phosphate group, leads to the dephosphorylated product 1b (Figure 1. ), which self-assembles into -sheet-like fibrous nanostructures, as described previously.…”

“…Escherichia coli, using the biocatalytically induced self-assembly of an aromatic peptide amphiphile, fluorenylmethoxycarbonyl-phenylalanine-phosphotyrosine(Fmoc-FpY) 39,42,45 (1a) -see Figure 1. The amphiphilic nature of 1a results in formation of spherical micelle structures in water.…”

“…), which self-assembles into -sheet-like fibrous nanostructures, as described previously. 45 In order to determine and analyze the motion of the enzyme conjugates a method was required to track the conjugates over time by visualizing individual vehicles. In principle this can be achieved by labeling the enzyme to enable observation via fluorescence microscopy.…”