The role of hydrophobicity in supramolecular polymer/surfactant catalysts: An understandable model for enzymatic catalysis.

Enzymes are highly significant catalysts, essential to biological systems, and a source of inspiration for the design of artificial enzymes. Although many models have been developed describing enzymatic catalysis, a deeper understanding of these biocatalysts remains a major challenge. Herein we detail the formation, characterization, performance, and catalytic mechanisms of a series of bio-inspired supramolecular polymer/surfactant complexes acting as artificial enzymes.

Coordination among Bond Formation/Cleavage in a Bifunctional-Catalyzed Fast Amide Hydrolysis: Evidence for an Optimized Intramolecular -Protonation Event.

A density functional theory (DFT) computational analysis, using the ωB97X-D functional, of a rapid amide cleavage in 2-carboxyphthalanilic acid (2CPA), where the amide group is flanked by two catalytic carboxyls, reveals key mechanistic information: (a) General base catalysis by a carboxylate coupled to general acid catalysis by a carboxyl is not operative. (b) Nucleophilic attack by a carboxylate on the amide carbonyl coupled to general acid catalysis at the amide oxygen can also be ruled out. (c) A mechanistic pathway that remains viable involves general acid proton delivery to the amide nitrogen by a carboxyl, while the other carboxylate engages in nucleophilic attack upon the amide carbonyl; a substantially unchanged amide carbonyl in the transition state; two concurrent bond-forming events; and a spatiotemporal-base rate acceleration.

Inhibitory and Cooperative Effects Regulated by pH in Host-Guest Complexation between Cationic Pillar[5]arene and Reactive 2-Carboxyphthalanilic Acid.

The study of host-guest complexation between reactive 2-carboxyphthalanilic acid (CPA) and two cationic pillararenes has been carried out. Host-guest complexation with significant kinetic effects was observed only with the smaller cavity size pillararene (P5A). Kinetics in the pH range 1.

Interaction vs Preorganization in Enzyme Catalysis. A Dispute That Calls for Resolution.

This essay focuses on the debate between Warshel et al. (proponents of preorganization) and Menger and Nome (proponents of spatiotemporal effects) over the source of fast enzyme catalysis. The Warshel model proposes that the main function of enzymes is to push the solvent coordinate toward the transition state.

Novel Supramolecular Nanoparticles Derived from Cucurbit[7]uril and Zwitterionic Surfactants.

Binding constants, log K ≈ 6.6 M, and NMR characterization of the complexes formed by sulfobetaines and cucurbit[7]uril (CB7) support the electrostatic interaction as the major driving force. This very strong binding motif is cross-linked by additional CB7 molecules, resulting in the formation of supramolecular nanoparticles (SNPs) with an average diameter of 172 nm and a negative surface potential.