Polymeric peptide pigments with sequence-encoded properties

Abstract

Melanins are a family of heterogeneous polymeric pigments that provide ultraviolet (UV) light protection, structural support, coloration, and free radical scavenging. Formed by oxidative oligomerization of catecholic small molecules, the physical properties of melanins are influenced by covalent and noncovalent disorder. We report the use of tyrosine-containing tripeptides as tunable precursors for polymeric pigments. In these structures, phenols are presented in a (supra-)molecular context dictated by the positions of the amino acids in the peptide sequence. Oxidative polymerization can be tuned in a sequence-dependent manner, resulting in peptide sequence-encoded properties such as UV absorbance, morphology, coloration, and electrochemical properties over a considerable range. Short peptides have low barriers to application and can be easily scaled, suggesting near-term applications in cosmetics and biomedicine.

Tunable Pentapeptide Self‐Assembled β‐Sheet Hydrogels

“…Shifting the Asp from the C‐ to the N‐terminus was shown to invert the conformation from a parallel to an antiparallel β‐sheet 20. Similarly, both the D2I3 and DI3D peptides contain charged Asp species situated at the termini of the sequence with regions of three repeat Ile residues.…”

“…The native tripeptide sequences discovered to self‐assemble into stable hydrogels have contained aromatic amino acids such as the KYF and DFY motifs 3, 20. Oligopeptides that consist of amino acids with aliphatic side chains have received less attention 21, 22.…”

“…Recently, it has been reported that Asp positioning can influence the stacking orientation of tripeptide β‐sheet assemblies 20. Shifting the Asp from the C‐ to the N‐terminus was shown to invert the conformation from a parallel to an antiparallel β‐sheet 20.…”

Selection of Secondary Structures of Heterotypic Supramolecular Peptide Assemblies by an Enzymatic Reaction

“…Being easily accessible via solid phase synthesis, peptides are becoming important building blocks for generating supramolecular assemblies for a wide range of applications such as antibacterial agent, [18] self-assembly with non-covalent interaction, [19] conjugating with anticancer drug, [20] and sequence control for generating melanin-like color. [21] Therefore, the use of enzyme reaction for controlling the secondary structure of peptides will contribute to design more sophisticated and intelligent soft biomaterials for a wide range of applications.…”

Chemoenzymatic Synthesis of Polypeptides for Use as Functional and Structural Materials

“…Ulijn and co-workers demonstrated that the melanin-mimetic materials with tunable coloration ability were synthesized by the self-assembly of tyrosine-containing tripeptides followed by oxidative polymerization using tyrosinase. [115] The polypeptides obtained by chemoenzymatic polymerization possess a free amino group at their N-termini and an ester group at their C-termini. These structural features are useful for further functionalization, including block copoly mer synthesis.…”