European Biophysics Journal最新文献

The global outbreak of COVID-19 pandemic has been accompanied by the emergence of numerous mutated forms of the SARS-CoV-2 virus, exhibiting an increasingly refined capacity to adapt to the human host. The majority of mutations affect viral proteins, particularly the Spike glycoprotein (S), leading to alterations in their physicochemical properties, in secondary structures and biological functions. In the present work, we performed, to the best of our knowledge, the first infrared spectroscopic characterization of monomeric spike glycoprotein subunits 1 (S1) of SARS-CoV-2 Beta variant at pH 7.4, combining the experimental results with Molecular Dynamic simulations, Definition of Secondary Structure of Proteins (DSSP) assignments and hydrophobicity calculations. This integrated approach has yielded valuable insights into the protein secondary structure, hydrophobic behaviour, conformational dynamics, and functional attributes, factors essential for a comprehensive understanding of the viral protein domain. Our results reveal that the SARS-CoV-2 S1 Beta variant is characterized by a secondary structure enriched with antiparallel β-sheets, as consistently supported by both experimental data and computational models. Moreover, a comparative analysis of the experimental results with hydrophobicity calculations indicates that the Beta variant exhibits a slightly more hydrophilic nature relative to the SARS-CoV-2 S1 Wild Type.

The EuPRAXIA project is a European initiative aimed at developing groundbreaking, ultra-compact accelerator research infrastructures based on novel plasma acceleration concepts. The EuPRAXIA@SPARC_LAB facility, located in the Italian National Institute for Nuclear Physics-Frascati National Laboratory, will be the first operating Free Electron Laser facility of EuPRAXIA, based on an accelerator module driven by an electron bunch driver. The Free Electron Laser will produce ultra-short photon pulses in the soft X-ray region. The photons will be delivered to an endstation, called AQUA, to perform a wide range of experiments in atomic and molecular physics, chemistry, and life sciences for both academic and industrial users. Thanks to its wavelength, which falls within the so-called 'water window', AQUA will be particularly well-suited for coherent imaging and ion spectroscopy measurements on biological samples at room temperature in a fully hydrated environment. This unique capability opens up innovative experimental schemes for studying biological systems in states that closely resemble their physiological conditions. This paper presents numerical simulations of coherent diffraction imaging and Coulomb explosion imaging experiments, anticipating future studies at AQUA on biological samples.

Enhancing protein stability while maintaining activity is a long-standing challenge in protein engineering, as modifications that benefit one property often compromise another. In this study, we leveraged a computational design strategy, CamSol Combination, to make a first step to improve the stability of purple acid phosphatase (PAP), a metalloprotein known for its distinctive pink color. PAP serves as a challenging model for engineering due to its complex redox-active site and the incorporation of iron ions critical to its function. Five mutations were introduced-H22R, A24P, F54P, H197P, and T208R-targeted to enhance thermal stability, as suggested by the computational design pipeline, while avoiding key functional regions. Experimental validation confirmed the choice of mutations with a 5 °C increase in thermal stability and retained enzymatic activity across a slightly expanded pH range. The mutations introduced subtle shifts in the enzyme's spectral and redox behavior, consistent with a lower energy of the oxidized state, and with dynamic light scattering data suggesting low aggregation. These results highlight the potential of computational approaches like the CamSol Combination to streamline protein engineering by enabling multi-trait optimization.

Curcumin (CUR), a bioactive compound extracted from the turmeric (Curcuma longa), has gathered considerable attention in recent years due to its claimed health benefits, including anti-inflammatory, antioxidant, and neuroprotective properties. The dysregulation of ion channel activity and the altered neuronal excitability in neurons has been identified as a key factor in the pathophysiology of neurological disease and a putative pharmacological target for therapeutic options. Therefore, we investigated by whole-cell patch-clamp the CUR's impact on the ionic currents in motoneuron-derived (MN-1) cells modeling SBMA and in human neuro-progenitor-cell (hNPCs)-derived neurons. CUR decreased viability in non-pathological MN-1 cells but showed increased resistance in pathological MN-1 cells, while mature neurons derived from hiPSCs remained unaffected under the same conditions. Electrophysiological studies revealed that CUR inhibits outward and inward currents in both MN-1 cell types, with a more pronounced effect in pathological cells. In hNPC-derived neurons, CUR also inhibited both currents and induced a negative shift in the voltage dependence of activation, suggesting reduced excitability. Our results indicate that further investigations are needed to confirm the role of CUR in the context of neurotherapeutics based on ion channel-targeting pharmacology.

Vitamin B12 (cobalamin, Cbl) is a coordination compound of the cobalt, located at the center of a corrin ring composed of four pyrrolic-like groups. The cobalt ion can be bound to a variety of upper axial ligands, which vary among different cobalamin forms, including hydroxocobalamin (OHCbl), cyanocobalamin (CNCbl), methylcobalamin (MeCbl), and adenosylcobalamin (AdoCbl). MeCbl and AdoCbl are considered the biologically active forms, serving as cofactors in the metabolism of methylmalonic acid (MMA) and homocysteine (HCY). Impaired conversion of these metabolites leads to their pathological accumulation, resulting in severe cellular damage. This is precisely what occurs in cblC deficiency, a rare inborn disorder caused by mutations in the MMACHC protein, which plays a crucial role in binding and processing the various cobalamin forms. Mutations affecting MMACHC function impair its ability to correctly handle cobalamins, leading to the disease. In this study, we evaluated the impact of various cobalamin forms, specifically AdoCbl, MeCbl, and CNCbl, on the stability and oligomeric organization of the wild type MMACHC protein, using circular dichroism spectroscopy, native gel electrophoresis, and small-angle X-ray scattering. Moreover, isothermal titration calorimetry experiments provided insights into the thermodynamic parameters governing MMACHC binding to these cobalamins. In addition, we also assessed how the R161Q mutation in MMACHC alters the affinity of this protein for the different vitamin B12 forms, leading to decreased stability and impaired homodimerization, a process likely relevant to its functional role. Our findings provide molecular insights into cblC pathogenesis and advance our understanding of MMACHC structure-function relationships.