Synthesis, self-assembly, and catalytic activity of histidine-based structured lipopeptides for hydrolysis reactions in water

Abstract

A new series of lipopeptides was designed to study their organocatalytic properties towards ester hydrolysis and the role of their self-assembled structures in catalysis. Synthesis of the catalysts was achieved by grafting fatty chains on tripeptides either at the C-terminal position or at the N-terminal extremity, affording amphiphilic character and self-assembling properties. Insertion of a histidine in the peptide sequence was chosen to bring about organocatalytic activity. Self-organization was evidenced first by the determination of critical aggregation concentrations and then by characterizing the aggregates formed by performing scattering techniques and microscopy. Variation of the structures (peptide sequence, hydrophobic character) led to the formation of various aggregates, from globular objects to fibers. All derivatives containing histidine presented a catalytic activity for the hydrolysis reaction of p-nitrophenyl acetate in aqueous solution. The influence of the self-organization on the catalysis was evidenced by showing different behaviors observed between the monomers and aggregates.

Amino-Acid-Based Metallo-Hydrogel That Acts Like an Esterase

“…There are a few reportson the histidine containing short peptide based hydrogelatorswith esterase activity [54][55][56][57][58] . Korendovychand coworkers have reported a Zn 2+ ion stabilized amyloid fibril with esterase acivity, whose catalytic activity drops several times in absence of the metal ion 59 .Therefore, it is of great interest to make amino acid/peptide based molecules with a ligating group that can bind with a suitable metal ion like Fe 3+ , Hg 2+ , Cu 2+ , Zn 2+ and any of these metal complexes can eventually self-associate by using various non-covalent interactions to form either gels or soluble aggregates.…”

Self-assembled nanoreactors based on peptides and proteins

“…1). In most systems, the hydrophobic portion of the amphiphile is composed of an alkyl chain of 8 to 16 carbons in length [9][10][11][12] although bolaamphiphilic peptides [13] and peptide amphiphiles with aromatic domains are also known [14]. Despite the catalytic applications of the specific fibers differing substantially, the origin for catalysis generally can be found in the peptide segment.…”

“…Despite the catalytic applications of the specific fibers differing substantially, the origin for catalysis generally can be found in the peptide segment. A (combination of) specific amino acid(s) can activate a reaction either directly [11,12,14] or indirectly via coordination to a metal catalyst [9,10,13].…”

“…More recent studies confirmed these findings and added to our knowledge of peptide amphiphile assembly into catalytic fibers. For example, it was revealed that the alkyl tails are tightly packed in a hydrophobic core that is surrounded by the peptide domain [9,10,12], which allows easy access for interacting metal catalysts [9] or substrates [12]. In addition, novel self-assembly mechanisms were discovered [13,14].…”

“…Most importantly, all these examples indicate that self-assembly of the peptide amphiphiles is essential to catalysis. Explanations for this are either a high density of catalysts presented at the surface of the nanofiber [11,13], chirality in the peptide assembly [13], or the presence of a hydrophobic domain that efficiently accommodates the substrate in close proximity to the reactive site [12].…”