Sulfur-containing compounds have diverse biological functions and are crucial in crop protection chemistry. In this study, a series of novel 1-methyl-1H-pyrazol-5-amine derivatives incorporating disulfide moieties were synthesized and evaluated for their antimicrobial properties. In vitro bioassays demonstrated that compound 7f displayed potent antifungal activity against Valsa mali, with an EC50 value of 0.64 mg/L, outperforming allicin (EC50 = 26.0 mg/L) but lower than tebuconazole (EC50 = 0.33 mg/L). In vivo experiments confirmed that compound 7f could effectively inhibit V. mali infection on apples at a concentration of 100 mg/L, similar to the positive control tebuconazole. Mechanistic studies revealed that compound 7f could induce hyphal shrinkage and collapse, trigger intracellular reactive oxygen species accumulation, modulate antioxidant enzyme activities, initiate lipid peroxidation, and ultimately cause irreversible oxidative damage to the cells of V. mali. Additionally, compound 7b exhibited notable antibacterial activity, particularly against Pseudomonas syringae pv. actinidiae, with a MIC90 value of 1.56 mg/L, surpassing the positive controls allicin, bismerthiazol, and streptomycin sulfate. These findings suggest that 1-methyl-1H-pyrazol-5-amine derivatives containing disulfide moieties hold promise as potent candidates for the development of novel antimicrobial agents.

[This corrects the article DOI: 10.3389/fmolb.2023.1258333.].

Disulfide bonds provide a convenient method for chemoselective alteration of peptide and protein structure and function. We previously reported that mild oxidation of a p53-derived bisthiol peptide (CTFANLWRLLAQNC) under dilute non-denaturing conditions led to unexpected disulfide-linked dimers as the exclusive product. The dimers were antiparallel, significantly α-helical, resistant to protease degradation, and easily reduced back to the original bisthiol peptide. Here we examine the intrinsic factors influencing peptide dimerization using a combination of amino acid substitution, circular dichroism (CD) spectroscopy, and X-ray crystallography. CD analysis of peptide variants suggests critical roles for Leu6 and Leu10 in the formation of stable disulfide-linked dimers. The 1.0 Å resolution crystal structure of the peptide dimer supports these data, revealing a leucine-rich LxxLL dimer interface with canonical knobs-into-holes packing. Two levels of higher-order oligomerization are also observed in the crystal: an antiparallel \"dimer of dimers\" mediated by Phe3 and Trp7 residues in the asymmetric unit and a tetramer of dimers mediated by Trp7 and Leu10. In CD spectra of Trp-containing peptide variants, minima at 227 nm provide evidence for the dimer of dimers in dilute aqueous solution. Importantly, and in contrast to the original dimer model, the canonical leucine-rich core and robust dimerization of most peptide variants suggests a tunable molecular architecture to target various proteins and evaluate how folding and oligomerization impact various properties, such as cell permeability.

Therapeutic oligonucleotides, such as antisense DNA, show promise in treating previously untreatable diseases. However, their applications are still hindered by the poor membrane permeability of naked oligonucleotides. Therefore, it is necessary to develop efficient methods for intracellular oligonucleotide delivery. Previously, our group successfully developed disulfide-based Membrane Permeable Oligonucleotides (MPON), which achieved enhanced cellular uptake and gene silencing effects through an endocytosis-free uptake mechanism. Herein, we report a new molecular design for the next generation of MPON, called trimer MPON. The trimer MPON consists of a tri-branched backbone, three α-lipoic acid units, and a spacer linker between the oligonucleotides and tri-branched cyclic disulfide unit. We describe the design, synthesis, and functional evaluation of the trimer MPON, offering new insights into the molecular design for efficient oligonucleotide delivery.

Redox modulation is a common posttranslational modification to regulate protein activity. The targets of oxidizing agents are cysteine residues (Cys), which have to be exposed at the surface of the proteins and are characterized by an environment that favors redox modulation. This includes their protonation state and the neighboring amino acids. The Cys redox state can be assessed experimentally by redox titrations to determine the midpoint redox potential in the protein. Exposed cysteine residues and putative intramolecular disulfide bonds can be predicted by alignments with structural data using dedicated software tools and information on conserved cysteine residues. Labeling with light and heavy reagents, such as N-ethylmaleimide (NEM), followed by mass spectrometric analysis, allows for the experimental determination of redox-responsive cysteine residues. This type of thiol redox proteomics is a powerful approach to assessing the redox state of the cell, e.g., in dependence on environmental conditions and, in particular, under abiotic stress.

The functionality of metal-organic frameworks (MOFs) is often encoded by specific chemical moieties found within these architectures. As such, new techniques to install increasingly more complex functionalities in MOFs are regularly being reported in the literature. One such functional group is the disulfide bond. The redox behavior of this covalent linkage renders MOFs responsive to stimuli, often under reducing conditions. Here, we review examples in which disulfide-containing MOFs are deployed in applications including drug delivery, therapeutic ferroptosis, exfoliation, energy storage, sensing, and others.

UNASSIGNED: Detection of oxidative stress level may lead us to understand the pathogenesis of COPD better and to search for new treatments. Oxidative stress levels have also been shown to be elevated in stable COPD patients. We aimed to investigate whether the stage of COPD affects the severity of inflammation-induced oxidative stress in patients with stable COPD.
UNASSIGNED: Between June 2019 and March 2020, all consecutive patients admitted to COPD-specific outpatient clinics were included. Patients were classified A, B, and E according to the GOLD guideline.
UNASSIGNED: The median age of 98 patients (Male: 92 (93.9 %)) was 65 (min-max: 49-86). A statistically significant difference was found between the groups in FEV1, FVC, and FEV1/FVC (p < 0.001). age, and thiols (r = -0.168, p = 0.049; r = -0.184, p = 0.035) and DS (r = -0.209, p = 0.019) were found to be negatively correlated at a low level. When adjusted for age, oxidative stress parameters were similar between stages.
UNASSIGNED: No difference between stages and oxidative stress parameters according to GOLD classification in stable COPD patients. Our results may be a guide for not using anti-inflammatory therapy except for attacks.

Environmental stressors disrupt secretory protein folding and proteostasis in the endoplasmic reticulum (ER), leading to ER stress. The unfolded protein response (UPR) senses ER stress and restores proteostasis by increasing the expression of ER-resident protein folding chaperones, such as protein disulfide isomerases (PDIs). In plants, the transmembrane ER stress sensor kinase, IRE1, activates the UPR by unconventionally splicing the mRNA encoding the bZIP60 transcription factor, triggering UPR gene transcription. The induced PDIs catalyze disulfide-based polypeptide folding to restore the folding capacity in the ER; however, the substrates with which PDIs interact are largely unknown. Here, we demonstrate that the Arabidopsis PDI-M subfamily member, PDI9, modulates the UPR through interaction with IRE1. This PDI9-IRE1 interaction was largely dependent on Cys63 in the first dithiol redox active domain of PDI9, and Cys233 and Cys107 in the ER lumenal domain of IRE1A and IRE1B, respectively. In vitro and in vivo, PDI9 coimmunoprecipitated with IRE1A and IRE1B. Moreover, the PDI9:RFP and Green Fluorescence Protein (GFP):IRE1 fusions exhibited strong interactions as measured by fluorescence lifetime imaging microscopy-fluorescence resonance energy transfer (FLIM-FRET) when coexpressed in mesophyll protoplasts. The UPR-responsive PDI9 promoter:mCherry reporter and the UPR-dependent splicing of the bZIP60 intron from the mRNA of the 35S::bZIP60-intron:GFP reporter were both significantly induced in the pdi9 mutants, indicating a derepression and hyperactivation of UPR. The inductions of both reporters were substantially attenuated in the ire1a-ire1b mutant. We propose a model in which PDI9 modulates the UPR through two competing activities: secretory protein folding and via interaction with IRE1 to maintain proteostasis in plants.

UNASSIGNED: Seronegative spondyloarthropathies (SpA) are a group of chronic diseases characterized by axial inflammation, oligoarthritis, and enthesitis. Oxidative stress may contribute to a wide range of rheumatologic diseases, including SpA. This prospective case-control study was designed to compare thiol-disulfide levels as a marker of oxidative stress between SpA patients and healthy controls.
UNASSIGNED: A total of 144 patients diagnosed with undifferentiated spondyloarthropathy (USpA, n = 97) or ankylosing spondylitis (AS, n = 47) were included along with 80 healthy controls. Serum native thiol (NT), total thiol (TT), and disulfide (D) levels were measured using the fully automated Erel method. The ratios NT/TT, D/TT, and D/NT were calculated. Thiol-disulfide levels were compared between the SpA groups and the healthy controls.
UNASSIGNED: The NT and NT/TT ratios were found to be significantly lower in the SpA group (p < 0.001). The disulfide, D/NT, and D/TT ratios were found to be significantly higher in the SpA group (p < 0.001). In pairwise comparisons between the SpA subgroups, the NT and TT levels were lower in the USpA group than in the AS group (p = 0.021), but serum disulfide levels were higher in the USpA group than in the AS group (p = 0.004). Among the patients with SpA, the group taking antitumor necrosis factor (anti-TNF) had lower TT measurements compared to the group taking conventional disease modifying antirheumatic drugs (DMARD) (p = 0.039).
UNASSIGNED: The thiol-disulfide balance is disturbed in favor of disulfide in SpA patients compared to healthy volunteers. Native and total thiol measurements correlate with acute phase reactants and might be used to monitor disease activity. Anti-TNF therapy might control the oxidative degenerative process better than the conventional DMARD in SpA patients.

Cataract disease is strongly associated with progressively accumulating oxidative damage to the extremely long-lived crystallin proteins of the lens. Cysteine oxidation affects crystallin folding, interactions, and light-scattering aggregation especially strongly due to the formation of disulfide bridges. Minimizing crystallin aggregation is crucial for lifelong lens transparency, so one might expect the ubiquitous lens crystallin superfamilies (α and βγ) to contain little cysteine. Yet, the Cys content of γ-crystallins is well above the average for human proteins. We review literature relevant to this longstanding puzzle and take advantage of expanding genomic databases and improved machine learning tools for protein structure prediction to investigate it further. We observe remarkably low Cys conservation in the βγ-crystallin superfamily; however, in γ-crystallin, the spatial positioning of Cys residues is clearly fine-tuned by evolution. We propose that the requirements of long-term lens transparency and high lens optical power impose competing evolutionary pressures on lens βγ-crystallins, leading to distinct adaptations: high Cys content in γ-crystallins but low in βB-crystallins. Aquatic species need more powerful lenses than terrestrial ones, which explains the high methionine content of many fish γ- (and even β-) crystallins. Finally, we discuss synergies between sulfur-containing and aromatic residues in crystallins and suggest future experimental directions.