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Chirality plays a fundamental role in natural phenomena, yet its manifestation on solid surfaces remains relatively unexplored. In this study, we investigate the formation of chiroptical melanin‐based self‐assembled films on quartz substrates, leveraging mussel‐inspired surface chemistry. Water‐soluble porphyrins serve as molecular synthons, facilitating the spontaneous formation of hetero‐aggregates in phosphate‐buffered saline containing L‐ or D‐DOPA. Spectroscopic analysis reveals chiral transfer from DOPA enantiomers to porphyrin hetero‐aggregates, followed by the disruption of these latter and subsequent generation of chiral melanin structures in solution. Quartz substrates inserted into these solutions spontaneously accumulate homogeneous melanin‐like films over days, demonstrating the feasibility of self‐assembly. The resulting films exhibit characteristic UV/Vis and CD spectra, with distinct signals indicating successful chiral induction. Interestingly, the AFM characterizations reveal a distinct surface morphology, and in addition, some thermal and mechanical properties have been taken into account. Overall, this study sheds light on the formation, stability, and chiroptical properties of melanin‐based films, paving the way for their application in various fields. [ABSTRACT FROM AUTHOR]

Many chronic diseases, including cancer and neurodegeneration, are linked to proteasome dysregulation. Proteasome activity, essential for maintaining proteostasis in a cell, is controlled by the gating mechanism and its underlying conformational transitions. Thus, developing effective methods to detect gate-related specific proteasome conformations could be a significant contribution to rational drug design. Since the structural analysis suggests that gate opening is associated with a decrease in the content of α-helices and β-sheets and an increase in random coil structures, we decided to explore the application of electronic circular dichroism (ECD) in the UV region to monitor the proteasome gating. A comparison of ECD spectra of wild type yeast 20S proteasome (predominantly closed) and an open-gate mutant (α3ΔN) revealed an increased intensity in the ECD band at 220 nm, which suggests increased contents of random coil and β-turn structures. This observation was further supported by evaluating ECD spectra of human 20S treated with low concentration of SDS, known as a gate-opening reagent. Next, to evaluate the power of ECD to probe a ligand-induced gate status, we treated the proteasome with H2T4, a tetracationic porphyrin that we showed previously to induce large-scale protein conformational changes upon binding to h20S. H2T4 caused a significant increase in the ECD band at 220 nm, interpreted as an induced opening of the 20S gate. In parallel, we imaged the gate-harboring alpha ring of the 20S with AFM, a technique that we used previously to visualize the predominantly closed gate in latent human or yeast 20S and the open gate in α3ΔN mutant. The results were convergent with the ECD data and showed a marked decrease in the content of closed-gate conformation in the H2T4-treated h20S. Our findings provide compelling support for the use of ECD measurements to conveniently monitor proteasome conformational changes related to gating phenomena. We predict that the observed association of spectroscopic and structural results will help with efficient design and characterization of exogenous proteasome regulators. [ABSTRACT FROM AUTHOR]

Protonated achiral H2TPPS4 spontaneously self‐arranges at acids pH and high ionic strength to build mesoscopic J‐aggregates that are intrinsically chiral. According to the symmetry rule aggregation leads to a racemate that, however, can be unbalanced by chemical (chiral pollutants) or physical stimuli (as vortexing the solution). Vortexing the title racemate, in principle, might either induce chiral separation or chiral enrichment. Indeed, herein it is shown that vortices enable the resolution of this racemic solution exploiting the tendency to deposit, onto the quartz cuvette walls, of the enantiomer favored by the stirring sense. Simultaneously, over time, it was found that the opposite chiral conformation becomes prevalent in solution realizing a significant enantiomeric resolution. Therefore, after removing all stirring‐favored chiral J‐aggregate from the solution, the recovering and isolating of the desired enantiomers from the cuvette walls was successfully obtained without complex procedures. In this sense, it has been demonstrated that the stirring forces are executively able to fulfil the chiral separation in H2TPPS4 J‐aggregates, employed as model of a self‐assembled system in aqueous solution. [ABSTRACT FROM AUTHOR]

The cover image is based on the Research Article Self‐Assembled Chiral Film Based on Melanin Polymers by Massimiliano Gaeta et al., https://doi.org/10.1002/chir.23695. [ABSTRACT FROM AUTHOR]