Minimalistic Artificial Catalysts with Esterase-Like Activity from Multivalent Nanofibers Formed by the Self-Assembly of Dipeptides

Abstract

Imitating and incorporating the multiple key structural features observed in natural enzymes into a minimalistic molecule to develop an artificial catalyst with outstanding catalytic efficiency is an attractive topic for chemists. Herein, we designed and synthesized one class of minimalistic dipeptide molecules containing a terminal −SH group and a terminal His-Phe dipeptide head linked by a hydrophobic alkyl chain with different lengths, marked as HS-C n+1-His-Phe (n = 4, 7, 11, 15, and 17; n + 1 represents the carbon atom number of the alkyl chain). The His (−imidazole), Phe (−CO2 –) moieties, the terminal −SH group, and a long hydrophobic alkyl chain were found to have important contributions to achieve high binding ability leading to outstanding absolute catalytic efficiency (k cat/K M) toward the hydrolysis reactions of carboxylic ester substrates.

Spectral-Sensing System for Distinguishing CH3OH and CD3OD

“…High-resolution mass spectrometry with the electron-spray ionization (ESI) source provided direct evidence for the formation of 4-nitrophenolate anions in the ester 1 methanol solution in the presence of DEA (Figure S2). Therefore, in the presence of DEA, the UV/vis absorption spectral response of ester 1 toward methanol could be attributed to the release of 4-nitrophenolate anions, owing to their strong CT effect. − This released 4-nitrophenolate anion can show the general structural feature of ground state-based CT molecules, where one electron-withdrawing group and one electron-donating group are connected to a conjugated system (in 4-nitrophenolate anion, –NO 2 is a strong electron-withdrawing group and hydroxyl anion is a strong electron-donating group). The extremely high selectivity of the spectral response of ester 1 toward methanol (Figure b) means that methanol is important for the release of 4-nitrophenolate anions.…”

“…Therefore, in such transesterification reactions, amines could be considered as catalysts. Furthermore, amines may also deprotonate −OH groups of released 4-nitrophenol (Figure b,ii) to generate 4-nitrophenolate anions and, therefore, a maximum UV/vis absorption spectral peak at ∼390 nm occurs, owing to the strong CT effect. − …”

Enzyme Mimics Based on Guanidinocalix[4]arene/ Nanodiamond Hybrid Systems with Phosphodiesterase Activity

“…[7][8][9][10][11] Alternative to the use of these platforms is resorting to nanostructured materials such as nanoparticles, [6,12,13] dendrimers/polymers [14,15] and surfactants. [16][17][18] In this context, nanodiamonds (NDs) [19][20][21] potentially offer a wide variety of possibilities entirely unexplored at the present time. These materials, prepared through detonation [19,21] or other techniques, [21][22][23] and after proper purification procedures, consist of a nanocrystalline diamond core with the simultaneous presence of hydrophobic graphenelike or graphite-like regions, consisting of conjugated sp 2 carbon atoms, and partially oxidized carbon atoms mainly present as hydroxy o carboxylate groups.…”

“…In these artificial systems, a number of active units are held together by conventional molecular scaffolds [7–11] . Alternative to the use of these platforms is resorting to nanostructured materials such as nanoparticles, [6,12,13] dendrimers/polymers [14,15] and surfactants [16–18] . In this context, nanodiamonds (NDs) [19–21] potentially offer a wide variety of possibilities entirely unexplored at the present time.…”