Profiling and optimized extraction of bioactive polyphenolic compounds from young, red-fleshed apple using eco-friendly deep eutectic solvents.

Red-fleshed apple cultivars with an enhanced content of polyphenolic compounds have attracted increasing interest due to their promising health benefits. Here, we have analysed the polyphenolic content of young, red-fleshed apples (RFA) and optimised extraction conditions of phenolics by utilising natural deep eutectic solvents (NDES). We also compare the antioxidant, neuroprotective and antimicrobial activities of NDES- and methanol-extracted phenolics from young RFA.

Structural Analysis and Identity Confirmation of Anthocyanins in Extracts by Direct Injection Ion Mobility-Mass Spectrometry.

Anthocyanins are a subclass of plant-derived flavonoids that demonstrate immense structural heterogeneity which is challenging to capture in complex extracts by traditional liquid chromatography-mass spectrometry (MS)-based approaches. Here, we investigate direct injection ion mobility-MS as a rapid analytical tool to characterize anthocyanin structural features in red cabbage () extracts. Within a 1.

Biochemical and structural characterization of meningococcal methylenetetrahydrofolate reductase.

Methylenetetrahydrofolate reductase (MTHFR) is a key metabolic enzyme in colonization and virulence of Neisseria meningitidis, a causative agent of meningococcal diseases. Here, the biochemical and structural properties of MTHFR from a virulent strain of N. meningitidis serogroup B (NmMTHFR) were characterized.

PPARγ Corepression Involves Alternate Ligand Conformation and Inflation of H12 Ensembles.

Inverse agonists of peroxisome proliferator activated receptor γ (PPARγ) have emerged as safer alternatives to full agonists for their reduced side effects while still maintaining impressive insulin-sensitizing properties. To shed light on their molecular mechanism, we characterized the interaction of the PPARγ ligand binding domain with SR10221. X-ray crystallography revealed a novel binding mode of SR10221 in the presence of a transcriptionally repressing corepressor peptide, resulting in much greater destabilization of the activation helix, H12, than without corepressor peptide.

Structural Study of Potent Triazole-Based Inhibitors of Biotin Protein Ligase.

The rise of multidrug-resistant bacteria, such as , has highlighted global urgency for new classes of antibiotics. Biotin protein ligase (BPL), a critical metabolic regulatory enzyme, is an important target that shows significant promise in this context. Here we report the docking, synthesis, and biological assay of a new series of -diphenylmethyl-1,2,3-triazole-based BPL (BPL) inhibitors (-) designed to probe the adenine binding site and define whole-cell activity for this important class of inhibitor.

YgiC and YjfC Possess Peptide─Spermidine Ligase Activity.

Polyamines and polyamine-containing metabolites are involved in many cellular processes related to bacterial cell growth and survival. In , the bifunctional enzyme glutathionylspermidine synthetase/amidase (GspSA) controls the production of glutathionylspermidine, which has a protective role against oxidative stress. also encodes two enzymes with homology to the synthetase domain of GspSA, YgiC, and YjfC; however, these do not catalyze the formation of glutathionylspermidine, and their catalytic function remained unknown.

A New 1,2,3-Triazole Scaffold with Improved Potency against Biotin Protein Ligase.

, a key ESKAPE bacteria, is responsible for most blood-based infections and, as a result, is a major economic healthcare burden requiring urgent attention. Here, we report docking, synthesis, and assay of -diphenylmethyl triazole-based analogues (-) designed to interact with the entire binding site of biotin protein ligase (BPL), an enzyme critical for the regulation of gluconeogenesis and fatty acid biosynthesis. The second aryl ring of these compounds enhances both BPL potency and whole cell activity against relative to previously reported mono-benzyl triazoles.

Discovery of an ʟ-amino acid ligase implicated in Staphylococcal sulfur amino acid metabolism.

Enzymes involved in Staphylococcus aureus amino acid metabolism have recently gained traction as promising targets for the development of new antibiotics, however, not all aspects of this process are understood. The ATP-grasp superfamily includes enzymes that predominantly catalyze the ATP-dependent ligation of various carboxylate and amine substrates. One subset, ʟ-amino acid ligases (LALs), primarily catalyze the formation of dipeptide products in Gram-positive bacteria, however, their involvement in S.

Designer D-peptides targeting the N-terminal region of α-synuclein to prevent parkinsonian-associated fibrilization and cytotoxicity.

The deposition of α-synuclein (αS) aggregates in the gut and the brain is ever present in cases of Parkinson's disease. While the central non-amyloidogenic-component (NAC) region of αS plays a critical role in fibrilization, recent studies have identified a specific sequence from within the N-terminal region (NTR, residues 36-42) as a key modulator of αS fibrilization. Due to the lack of effective therapeutics which specifically target αS aggregates, we have developed a strategy to prevent the aggregation and subsequent toxicity attributed to αS fibrilization utilizing NTR targeting peptides.

Polyphenol characterisation and diverse bioactivities of native Australian lilly pilly () extract.

Magenta lilly pilly () is an Australian native tree that produces berry fruits that are rich in phytochemicals reportedly beneficial to human health. Here we explored the biological activities of polyphenol-enriched extracts from the magenta lilly pilly fruit, benchmarking it against traditional sources including purple sweet potato and blackberry. We show that the extracts exert potent antioxidant and neuroprotective properties as well as antimicrobial activity against .

A structural model of the human plasminogen and Aspergillus fumigatus enolase complex.

The metabolic enzyme, enolase, plays a crucial role in the cytoplasm where it maintains cellular energy production within the process of glycolysis. The main role of enolase in glycolysis is to convert 2-phosphoglycerate to phosphoenolpyruvate; however, enolase can fulfill roles that deviate from this function. In pathogenic bacteria and fungi, enolase is also located on the cell surface where it functions as a virulence factor.

Structural insights into the antifungal drug target guanosine monophosphate synthase from Aspergillus fumigatus.

Purine biosynthesis is a fundamental cellular process that sustains life by maintaining the intracellular pool of purines for DNA/RNA synthesis and signal transduction. As an integral determinant of fungal survival and virulence, the enzymes in this metabolic pathway have been pursued as potential antifungal targets. Guanosine monophosphate (GMP) synthase has been identified as an attractive target as it is essential for virulence in the clinically prominent fungal pathogens Aspergillus fumigatus, Candida albicans and Cryptococcus neoformans.

Structural and mechanistic insights into amyloid-β and α-synuclein fibril formation and polyphenol inhibitor efficacy in phospholipid bilayers.

Under certain cellular conditions, functional proteins undergo misfolding, leading to a transition into oligomers which precede the formation of amyloid fibrils. Misfolding proteins are associated with neurodegenerative diseases such as Alzheimer's and Parkinson's diseases. While the importance of lipid membranes in misfolding and disease aetiology is broadly accepted, the influence of lipid membranes during therapeutic design has been largely overlooked.

Polyphenol Honokiol and Flavone 2',3',4'-Trihydroxyflavone Differentially Interact with α-Synuclein at Distinct Phases of Aggregation.

The association between protein aggregation and neurodegenerative diseases such as Parkinson's disease continues to be well interrogated but poorly elucidated at a mechanistic level. Nevertheless, the formation of amyloid fibrils from the destabilization and misfolding of native proteins is a molecular hallmark of disease. Consequently, there is ongoing demand for the identification and development of small molecules which prevent fibril formation.

Nucleoside selectivity of Aspergillus fumigatus nucleoside-diphosphate kinase.

Aspergillus fumigatus infections are rising at a disconcerting rate in tandem with antifungal resistance rates. Efforts to develop novel antifungals have been hindered by the limited knowledge of fundamental biological and structural mechanisms of A. fumigatus propagation.

Short Photoswitchable Antibacterial Peptides.

Three photoswitchable tetrapeptides, based on a known synthetic antibacterial, were designed and synthesized to determine activity against Staphylococcus aureus. Each peptide contains an azobenzene photoswitch incorporated into either the N-terminal side chain (1), C-terminal side chain (2), or the C-terminus (3) to allow reversible switching between cis- and trans-enriched photostationary states. Biological assays revealed that the C-terminus azobenzene (3) possessed the most potent antibacterial activity, with an MIC of 1 μg/mL.

Rationally designed peptide-based inhibitor of Aβ42 fibril formation and toxicity: a potential therapeutic strategy for Alzheimer's disease.

Amyloid beta peptide (Aβ42) aggregation in the brain is thought to be responsible for the onset of Alzheimer's disease, an insidious condition without an effective treatment or cure. Hence, a strategy to prevent aggregation and subsequent toxicity is crucial. Bio-inspired peptide-based molecules are ideal candidates for the inhibition of Aβ42 aggregation, and are currently deemed to be a promising option for drug design.

Interrogating the higher order structures of snake venom proteins using an integrated mass spectrometric approach.

Snake venoms contain complex mixtures of proteins vital for the survival of venomous snakes. Aligned with their diverse pharmacological activities, the protein compositions of snake venoms are highly variable, and efforts to characterise the primary structures of such proteins are ongoing. Additionally, a significant knowledge gap exists in terms of the higher-order protein structures which modulate venom potency, posing a challenge for successful therapeutic applications.

The molecular chaperone β-casein prevents amorphous and fibrillar aggregation of α-lactalbumin by stabilisation of dynamic disorder.

Deficits in protein homeostasis (proteostasis) are typified by the partial unfolding or misfolding of native proteins leading to amorphous or fibrillar aggregation, events that have been closely associated with diseases including Alzheimer's and Parkinson's diseases. Molecular chaperones are intimately involved in maintaining proteostasis, and their mechanisms of action are in part dependent on the morphology of aggregation-prone proteins. This study utilised native ion mobility-mass spectrometry to provide molecular insights into the conformational properties and dynamics of a model protein, α-lactalbumin (α-LA), which aggregates in an amorphous or amyloid fibrillar manner controlled by appropriate selection of experimental conditions.

Fabrication of Piperazine Functionalized Polymeric Monolithic Tip for Rapid Enrichment of Glycopeptides/Glycans.

Enrichment strategies are designed for the pretreatment of low-abundance glycans and glycopeptides prior to mass spectrometric (MS) analysis. Here, a tip-based strategy is being reported for the enrichment of glycopeptides and glycans using a piperazine modified polymeric monolithic tip. The tip is fabricated using the free radical polymerization.

C-Phycocyanin from Spirulina Inhibits α-Synuclein and Amyloid-β Fibril Formation but Not Amorphous Aggregation.

Proteinopathies including cataracts and neurodegenerative diseases, such as Alzheimer's and Parkinson's disease, are characterized by a series of aberrant protein folding events, resulting in amorphous aggregate or amyloid fibril formation. In the latter case, research has heavily focused on the development of small-molecule inhibitors with limited success during clinical trials. However, very few studies have focused on utilizing exogenous proteins as potential aggregation inhibitors.

The influence of the N-terminal region proximal to the core domain on the assembly and chaperone activity of αB-crystallin.

αB-Crystallin (HSPB5) is a small heat-shock protein that is composed of dimers that then assemble into a polydisperse ensemble of oligomers. Oligomerisation is mediated by heterologous interactions between the C-terminal tail of one dimer and the core "α-crystallin" domain of another and stabilised by interactions made by the N-terminal region. Comparatively little is known about the latter contribution, but previous studies have suggested that residues in the region 54-60 form contacts that stabilise the assembly.

Evaluating the Effect of Phosphorylation on the Structure and Dynamics of Hsp27 Dimers by Means of Ion Mobility Mass Spectrometry.

The quaternary structure and dynamics of the human small heat-shock protein Hsp27 are linked to its molecular chaperone function and influenced by post-translational modifications, including phosphorylation. Phosphorylation of Hsp27 promotes oligomer dissociation and can enhance chaperone activity. This study explored the impact of phosphorylation on the quaternary structure and dynamics of Hsp27.

Stability of the octameric structure affects plasminogen-binding capacity of streptococcal enolase.

Group A Streptococcus (GAS) is a human pathogen that has the potential to cause invasive disease by binding and activating human plasmin(ogen). Streptococcal surface enolase (SEN) is an octameric α-enolase that is localized at the GAS cell surface. In addition to its glycolytic role inside the cell, SEN functions as a receptor for plasmin(ogen) on the bacterial surface, but the understanding of the molecular basis of plasmin(ogen) binding is limited.

Phosphomimics destabilize Hsp27 oligomeric assemblies and enhance chaperone activity.

Serine phosphorylation of the mammalian small heat-shock protein Hsp27 at residues 15, 78, and 82 is thought to regulate its structure and chaperone function; however, the site-specific impact has not been established. We used mass spectrometry to assess the combinatorial effect of mutations that mimic phosphorylation upon the oligomeric state of Hsp27. Comprehensive dimerization yielded a relatively uncrowded spectrum, composed solely of even-sized oligomers.