Enzyme-Reactive Self-Assembling Peptides for Biomacromolecular Functionalization

Supramolecular nanostructures comprised of self-assembling peptides are a promising soft material in bionanotechnology. They can form nanocarriers of small drugs/biomolecules for pharmaceuticals, nanofibrous networks as an artificial extracellular matrix for regenerative medicine, and so forth. Enzyme-responsiveness of these materials has recently been attracted attention because it enables the efficient and highly specific control of materials functions under physiological conditions. However most of the published work utilized enzymes to fabricate or decompose the assembly, and enzymatic decoration of the nanostructures has not been focused.

Herein we developed novel peptide assemblies that can be further functionalized with biomacromolecules using enzyme catalysis. The enzyme used in our study is microbial transglutaminase, MTG. MTG catalyzes the acyl transfer reaction between γ-carboxyamide of glutamine (Q) residues and ε-amino group of lysine (K) residues or primary amines. MTG-recognizable self-assembling peptides were designed by introducing aromatic group and hydrophobic amino acid sequence at the N-terminal of Q. As a biomacromolecule, enhanced green fluorescent protein (EGFP) was employed, of which C-terminal was attached with the MTG-recognizable lysine-containing sequence, K-tag. We synthesized several self-assembling peptides and investigated the influence of the assembled structures on the MTG reactivity. The enzymatic functionalization of EGFP on the peptides structures was also examined.