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1.
Persulphide-responsive transcriptional regulation and metabolism in bacteria.
Shimizu, T, Masuda, S
Journal of biochemistry. 2020;(2):125-132
Abstract
Hydrogen sulphide (H2S) impacts on bacterial growth both positively and negatively; it is utilized as an electron donor for photosynthesis and respiration, and it inactivates terminal oxidases and iron-sulphur clusters. Therefore, bacteria have evolved H2S-responsive detoxification mechanisms for survival. Sulphur assimilation in bacteria has been well studied, and sulphide:quinone oxidoreductase, persulphide dioxygenase, rhodanese and sulphite oxidase were reported as major sulphide-oxidizing enzymes of sulphide assimilation and detoxification pathways. However, how bacteria sense sulphide availability to control H2S and sulphide metabolism remains largely unknown. Recent studies have identified several bacterial (per)sulphide-sensitive transcription factors that change DNA-binding affinity through persulphidation of specific cysteine residues in response to highly reactive sulphur-containing chemicals and reactive sulphur species (RSS). This review focuses on current understanding of the persulphide-responsive transcription factors and RSS metabolism regulated by RSS sensory proteins.
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2.
Anti-inflammatory medications for the treatment of pediatric obstructive sleep apnea.
Kuhle, S, Urschitz, MS
Paediatric respiratory reviews. 2020;:35-36
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3.
[Research progress in mineral Chinese medicine realgar].
Song, LL, Han, DY, Lin, RC, Huang, JM, Guan, J
Zhongguo Zhong yao za zhi = Zhongguo zhongyao zazhi = China journal of Chinese materia medica. 2019;(3):433-440
Abstract
Realgar is a mineral traditional medicine with definite efficacy. The function of realgar is detoxicating, insecticiding, eliminating dampness and phlegm, etc. It is widely applied in clinical practice by compatibility medicines. However, the safety and scientificalness of clinical application are questioned because of the toxic effect caused by arsenic compounds. At present, there are still many problems in the research of realgar, which are mainly manifested in three areas: the expression of main components and effective substances are inconsistent; the anti-tumor mechanism is difficult to explain at the molecular level; the mechanism of compatibility is not clear. As a result, realgar and realgar-containing Chinese patent medicines are frequently prohibited from entering the international market, and the reputation of traditional Chinese medicine is also damaged. This paper would analyze the research status of realgar at home and abroad as well as its problems from its main components, effective substances, anti-tumor mechanism and compatibility mechanism. In view of these difficulties, quantum chemical calculation method is proposed to solve them, so as to make up for the shortcomings and limitations of experimental technology and experimental conditions, reduce the cost of realgar research and improve research efficiency. Moreover, it provides inspiration for research of other mineral medicine.
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4.
Application of the Pentafluorosulfanyl Group as a Bioisosteric Replacement.
Sowaileh, MF, Hazlitt, RA, Colby, DA
ChemMedChem. 2017;(18):1481-1490
Abstract
The success of fluorinated molecules in drug design has led medicinal chemists to search for new fluorine-containing substituents. A major recently developed group is the pentafluorosulfanyl group. This group is stable under physiological conditions and displays unique physical and chemical properties. There are currently few synthetic methods to install the SF5 group, yet efforts to integrate this group into lead optimization continue unabated. Typically, the SF5 group has been used as a replacement for trifluoromethyl, tert-butyl, halogen, or nitro groups. In this review, the use of the SF5 group as a bioisosteric replacement for each of these three functionalities is compared and contrasted across various groups of biologically active molecules. The organization and presentation of these data should be instructive to medicinal chemists considering to design synthetic strategies to access SF5 -substituted molecules.
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5.
Bacterial magnetosome and its potential application.
Yan, L, Da, H, Zhang, S, López, VM, Wang, W
Microbiological research. 2017;:19-28
Abstract
Bacterial magnetosome, synthetized by magnetosome-producing microorganisms including magnetotactic bacteria (MTB) and some non-magnetotactic bacteria (Non-MTB), is a new type of material comprising magnetic nanocrystals surrounded by a phospholipid bilayer. Because of the special properties such as single magnetic domain, excellent biocompatibility and surface modification, bacterial magnetosome has become an increasingly attractive for researchers in biology, medicine, paleomagnetism, geology and environmental science. This review briefly describes the general feature of magnetosome-producing microorganisms. This article also highlights recent advances in the understanding of the biochemical and magnetic characteristics of bacterial magnetosome, as well as the magnetosome formation mechanism including iron ions uptake, magnetosome membrane formation, biomineralization and magnetosome chain assembly. Finally, this review presents the potential applications of bacterial magnetosome in biomedicine, wastewater treatment, and the significance of mineralization of magnetosome in biology and geology.
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6.
Thioether-derived Macrocycle for Peptide Secondary Structure Fixation.
Tian, Y, Yang, D, Ye, X, Li, Z
Chemical record (New York, N.Y.). 2017;(9):874-885
Abstract
Recently, we developed methods to stabilize peptides into various secondary structures, including α-helix, type III turn and β-hairpin via proper thioether based macrocyclization. These conformationally constrained peptidomimetics confer enhanced biophysical properties and provide a valuable avenue towards clinically-relevant therapeutic molecules. In this personal account, thioether-derived macrocyclization methods developed by our group for stabilization of α-helix, type-III β turn and β-hairpin conformations are discussed.
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7.
Biological chemistry of hydrogen sulfide and persulfides.
Cuevasanta, E, Möller, MN, Alvarez, B
Archives of biochemistry and biophysics. 2017;:9-25
Abstract
Hydrogen sulfide (H2S) has been traditionally considered to be a toxic molecule for mammals. However, it can be formed endogenously and exert physiological effects with potential health benefits. H2S can partition two-fold in biological membranes and traverse them rapidly, diffusing between compartments. H2S reactivity has similarities to that of thiols, although it is less nucleophilic than thiols and it can form different products. H2S can react with oxidants derived from the partial reduction of oxygen, but direct scavenging is unlikely to explain H2S protective actions. Important effects are exerted on mitochondria including the stimulation or the inhibition of the electron transport chain. Possible mechanisms for unleashing biological consequences are the reactions with metal centers and with thiol oxidation products. The reactions of H2S with disulfides (RSSR) and sulfenic acids (RSOH) lead to the formation of persulfides (RSSH). Persulfides have enhanced nucleophilicity with respect to the corresponding thiol, consistent with the alpha effect. Besides, the inner and outer sulfurs can both act as electrophiles. In this review, we describe the reactions of H2S with oxidized thiol products and the properties of the persulfides formed in the context of the chemical biology of H2S.
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8.
Trade-Off Between Dimethyl Sulfide and Isoprene Emissions from Marine Phytoplankton.
Dani, KGS, Loreto, F
Trends in plant science. 2017;(5):361-372
Abstract
Marine phytoplankton emit volatile organic compounds (VOCs) such as dimethyl sulfide (DMS) and isoprene that influence air quality, cloud dynamics, and planetary albedo. We show that globally (i) marine phytoplankton taxa tend to emit either DMS or isoprene, and (ii) sea-water surface concentration and emission hotspots of DMS and isoprene have opposite latitudinal gradients. We argue that a convergence of antioxidant functions between DMS and isoprene is possible, driven by potential metabolic competition for photosynthetic substrates. Linking phytoplankton emission traits to their latitudinal niches, we hypothesize that natural selection favors DMS emission in cold (polar) waters and isoprene emission in warm (tropical) oceans, and that global warming may expand the geographic range of marine isoprene-emitters. A trade-off between DMS and isoprene at metabolic, organismal, and geographic levels may have important consequences for future marine biosphere-atmosphere interactions.
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9.
The Sulfur Metabolite Lanthionine: Evidence for a Role as a Novel Uremic Toxin.
Perna, AF, Zacchia, M, Trepiccione, F, Ingrosso, D
Toxins. 2017;(1)
Abstract
Lanthionine is a nonproteinogenic amino acid, composed of two alanine residues that are crosslinked on their β-carbon atoms by a thioether linkage. It is biosynthesized from the condensation of two cysteine molecules, while the related compound homolanthionine is formed from the condensation of two homocysteine molecules. The reactions can be carried out by either cystathionine-β-synthase (CBS) or cystathionine-γ-lyase (CSE) independently, in the alternate reactions of the transsulfuration pathway devoted to hydrogen sulfide biosynthesis. Low plasma total hydrogen sulfide levels, probably due to reduced CSE expression, are present in uremia, while homolanthionine and lanthionine accumulate in blood, the latter several fold. Uremic patients display a derangement of sulfur amino acid metabolism with a high prevalence of hyperhomocysteinemia. Uremia is associated with a high cardiovascular mortality, the causes of which are still not completely explained, but are related to uremic toxicity, due to the accumulation of retention products. Lanthionine inhibits hydrogen sulfide production in hepatoma cells, possibly through CBS inhibition, thus providing some basis for the biochemical mechanism, which may significantly contribute to alterations of metabolism sulfur compounds in these subjects (e.g., high homocysteine and low hydrogen sulfide). We therefore suggest that lanthionine is a novel uremic toxin.
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10.
Diversity and ecology of and biomineralization by magnetotactic bacteria.
Lin, W, Pan, Y, Bazylinski, DA
Environmental microbiology reports. 2017;(4):345-356
Abstract
Magnetotactic bacteria (MTB) biomineralize intracellular, membrane-bounded crystals of magnetite (Fe3 O4 ) and/or greigite (Fe3 S4 ) called magnetosomes. MTB play important roles in the geochemical cycling of iron, sulfur, nitrogen and carbon. Significantly, they also represent an intriguing model system not just for the study of microbial biomineralization but also for magnetoreception, prokaryotic organelle formation and microbial biogeography. Here we review current knowledge on the ecology of and biomineralization by MTB, with an emphasis on more recent reports of unexpected ecological and phylogenetic findings regarding MTB. In this study, we conducted a search of public metagenomic databases and identified six novel magnetosome gene cluster-containing genomic fragments affiliated with the Deltaproteobacteria and Gammaproteobacteria classes of the Proteobacteria phylum, the Nitrospirae phylum and the Planctomycetes phylum from the deep subseafloor, marine oxygen minimum zone, groundwater biofilm and estuary sediment, thereby extending our knowledge on the diversity and distribution of MTB as well deriving important information as to their ecophysiology. We point out that the increasing availability of sequence data will facilitate researchers to systematically explore the ecology and biomineralization of MTB even further.