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Nicolajsen Tobiasen posted an update 1 year, 5 months ago
The tear is a biological fluid that has the diagnostic potential for ocular diseases. Extracellular vesicles (EVs), widly detected in various biofluids including tears, are nanoparticles released by living cells and considered as promising detection sources for noninvasive liquid biopsy. Understanding the roles of tears and tear-EVs in ocular diseases such as dry eye can facilitate the studies of clinical diagnosis, which usually entails detecting such liquid objects with a rapid and effective method. In this study, we used a mass spectrometry-based strategy to analyze peptidome/proteome profiles of tears and EVs for rapid dry eye diagnosis. Nanosized EVs were isolated from tears of both healthy control (HC) individuals and dry eye syndrome (DES) patients, and the tear compositions were further analyzed by tracking their fingerprints with matrix-assisted laser desorption ionization/time-of-flight mass spectrometry. The fingerprints of tear-EVs could be observed in a dose-dependent manner and tears, allowing for comparison of the discriminant peaks between tears and EVs. By analyzing these peaks, the fingerprints of both tear and tear-EVs were showed to have the capability of distinguishing patients with DES from HC donors and providing an efficient way for screening potential DES biomarkers. The proposed tear and EV fingerprinting approach is expected to be a potential tool in the rapid diagnosis of ocular diseases and in-depth research on pathogenesis. Data are available via ProteomeXchange with identifier PXD020217.Knowledge of phosphosite occupancy is important to explain biological functions for phosphoproteomics studies. Determination of occupancy using three ratios, i.e., protein ratio, phosphopeptide ratio, and its unmodified peptide counterpart ratio between a pair of samples, is straightforward but suffers from large variances. Here, an optimized protocol of offline fractionation and LC-MS analysis combined with an integrated data processing approach was developed to improve the reliability of the phosphosite occupancy determination. An outlier score S was introduced to evaluate the deviation between the ratio of absolute occupancy and relative occupancy and was further used to define the bounds of a credible interval of absolute occupancy. For a preset product-moment correlation coefficient, the credible interval can be resolved through the S value. Using this strategy, more than 176k unique peptide sequences covering 11k protein groups and 32k phosphosites were identified from one paired hepatocellular carcinoma (HCC) sample and about 3000 reliable phosphosite occupancies were finally determined. By bioinformatics analysis, we characterized the biological properties associated with phosphorylation sites with different quantified occupancies from the paired HCC sample. find more Data are available via ProteomeXchange with identifier PXD019045.The world is currently facing the COVID-19 pandemic caused by the SARS-CoV-2 virus. The pandemic is causing the death of people around the world, and public and social health measures to slow or prevent the spread of COVID-19 are being implemented with the involvement of all members of society. Research institutions are accelerating the discovery of vaccines and therapies for COVID-19. In this work, molecular docking was used to study (in silico) the interaction of 24 ligands, divided into four groups, with four SARS-CoV-2 receptors, Nsp9 replicase, main protease (Mpro), NSP15 endoribonuclease, and spike protein (S-protein) interacting with human ACE2. The results showed that the antimalarial drug Metaquine and anti-HIV antiretroviral Saquinavir interacted with all the studied receptors, indicating that they are potential candidates for multitarget drugs for COVID-19.In this work, the copolymer poly[(9,9-dioctylfluorene)-co-(3-hexylthiophene)] was employed as a matrix for immobilizing phytase, aiming at the detection of phytic acid. The copolymer was spread on the air-water interface forming Langmuir monolayers and phytase adsorbed from the aqueous subphase. The interactions between the copolymer and the enzyme components were investigated with surface pressure and surface potential-area isotherms, Brewster angle microscopy, and polarization modulation infrared reflection-absorption spectroscopy (PM-IRRAS). The enzyme could be incorporated in the monolayers from the aqueous subphase, expanding the copolymer films and maintaining its secondary structure. The polymeric films presented a morphological heterogeneous pattern at the air-water interface because of the ability of their chains to fold and entangle, causing inherent defects in the organization as well as unbalanced lateral distribution at the air-water interface because of the formation of aggregates. The interfacial films were transferred to solid supports as Langmuir-Blodgett films and characterized by PM-IRRAS and scanning electronic microscopy, which showed not only the co-transfer of the enzyme but also the maintenance of their heterogeneous morphological pattern. The enzymatic activity of the blended film was analyzed by UV-vis spectroscopy and allowed the estimation of the value of the Michaelis constant (13.08 mM), demonstrating the feasibility of the system to selectively detect phytic acid for biosensing purposes.The properties of enzymes packaged within the coat protein shell of virus-like particles (VLPs) were studied to provide a comprehensive assessment of such factors. Such entrainment did not seem to perturb enzyme function, but it did significantly enhance enzyme stability against several denaturing stimuli such as heat, organic solvents, and chaotropic agents. This improvement in performance was found to be general and independent of the number of independent subunits required and of the number of catalytically active enzymes packaged. Packaged enzymes were found by measurements of intrinsic tryptophan fluorescence to retain some of their native folded structure even longer than their catalytic activity, suggesting that protein folding is a significant component of the observed catalytic benefits. While we are unable to distinguish between kinetic and thermodynamic effects – including inhibition of enzyme unfolding, acceleration of refolding, and biasing of folding equilibria – VLP packaging appears to represent a useful general strategy for the stabilization of enzymes that operate on diffusible substrates and products.

