Insight into the esterase like activity demonstrated by an imidazole appended self-assembling hydrogelator

Abstract

A low molecular weight hydrogelator with a covalently appended imidazole moiety is reported. Capable of percolating water in the pH range of 6 to 8, it proves to be an efficient catalyst upon self-assembly, showing Michaelis-Menten type kinetics. Activities at different pH values correlated with dramatic structural changes were observed. It can hydrolyse p-nitrophenyl acetate (pNPA) as well as inactivated esters, and L and D-phenylalanine methyl esters. The enhanced activity can be related to the conglomeration of catalytic groups upon aggregation resulting in their close proximity and the formation of hydrophobic pockets.

Short Peptides in Minimalistic Biocatalyst Design

“…It has also been demonstrated that design of the peptides can be used to alter catalytic activity, enhance stability, and provide insights into the mechanisms of reactions. The most effective approaches seem to be based on primary peptide sequence, nanosurfaces/scaffolds and multivalency with an especially impressive rate enhancement observed in a system where cooperative interactions between imidazoles were facilitated [40]. The presence of metal ions has also been shown to improve activity [35].…”

“…Finally, a recent article from Escuder et al highlights a low molecular weight bola-amphiphile hydrogelator composed of an alkyl functionalised at both ends with a valine residue which is covalently linked to an imidazole moiety [40]. This gelator has proven to be an efficient catalyst once self-assembled and can hydrolyse p-NPA with k cat calculated to range from 2.1 -2.6 x 10 2 s -1 at pH 6-8.…”

Peptide‐Based Molecular Hydrogels as Supramolecular Protein Mimics

“…However, the hydrolysis of non‐activated substrates is still a challenge. In light of this, we recently reported an imidazole‐appended l ‐valine bolaamphiphile hydrogelator that is able to catalyze the hydrolysis of phenylalanine methyl ester at neutral pH, albeit with longer reaction times than for activated esters . Nevertheless, perhaps the biggest challenge for the next generation of peptide‐based catalytic gels is to achieve aqueous catalysis of bonds that are difficult to break, such as amide and phosphate ester bonds (requiring protease or phosphatase‐like activity).…”

A dipeptide‐based superhydrogel: Removal of toxic dyes and heavy metal ions from waste water

“…The network structure encapsulates large number of water molecules to form a hydrogel. Amino acid/peptide‐based gels are endowed with variety of applications including drug delivery, tissue engineering, oil‐spill recovery, and waste water treatment . They can also be used for making nanoclusters and nanoparticles, photo‐switching materials and for other biomedical applications …”