Multi-enzyme cascade reactions using protein-polymer surfactant self-standing films

Hierarchical self-assembly is used to fabricate bio-catalytically active, self-supporting protein-polymer surfactant films capable of sustaining two-or three-enzyme cascade reactions

Neat Protein–Polymer Surfactant Bioconjugates as Universal Solvents

Solvents, particularly those having low volatility, are of great interest for the biocatalytic synthesis of utility chemicals and fuels. We show novel and universal solvent-like properties of a neat and water-less polymer surfactant–bovine serum albumin (BSA) conjugated material (WL-PS<i>p</i>BSA). This highly viscous, nonvolatile material behaves as a liquid above its solid–liquid transition temperature (∼25–27 °C) and can be used as a solvent for variety of completely dry solutes of different sizes and surface chemistries. We show using a combination of optical microscopy and steady -state and time-resolved fluorescence spectroscopy that dry and powdered dyes (hydrophobic Coumarin 153 (C153)), enzymes (α-chymotrypsin (α-Chy)), or even 1 μm microparticles (diffusion coefficient ca. three orders slower than C153), can be solubilized and completely dispersed in the WL-PS<i>p</i>BSA solvent above 25 °C. While C153, irrespective of its mode of addition to WL-PS<i>p</i>BSA, binds similarly to BSA, α-Chy can be stabilized and activated to perform its hydrolysis function, even at 100 °C. This work therefore provides insights into the form of universal solvent characteristic property for this new class of nonaqueous, nonvolatile, biodegradable protein–polymer surfactant-based conjugated materials and suggests potential new avenues that can have a huge impact on biocatalysis, bionanotechnology, drug delivery, and other applications

Isolation of a Highly Reactive β‑Sheet-Rich Intermediate of Lysozyme in a Solvent-Free Liquid Phase

The thermal denaturation of solvent-free liquid lysozyme at temperatures in excess of 200 °C was studied by synchrotron radiation circular dichroism spectroscopy. Temperature-dependent changes in the secondary structure were used to map the equilibrium denaturation pathway and characterize a reactive β-sheet-rich unfolding intermediate that was stable in the solvent-free liquid phase under anhydrous conditions but which underwent irreversible aggregation in the presence of water. The unfolding intermediate had a transition temperature of 78 °C and was extremely stable to temperature, eventually reaching the fully denatured state at 178 °C. We propose that the three-stage denaturation pathway arises from the decreased stability of the native state due to the absence of any appreciable hydrophobic effect, along with an entropically derived stabilization of the reactive intermediate associated with molecular crowding in the solvent-free liquid