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Proceedings of the National Academy of... Mar 2020Iron is the limiting factor for biological production over a large fraction of the surface ocean because free iron is rapidly scavenged or precipitated under aerobic...
Iron is the limiting factor for biological production over a large fraction of the surface ocean because free iron is rapidly scavenged or precipitated under aerobic conditions. Standing stocks of dissolved iron are maintained by association with organic molecules (ligands) produced by biological processes. We hypothesize a positive feedback between iron cycling, microbial activity, and ligand abundance: External iron input fuels microbial production, creating organic ligands that support more iron in seawater, leading to further macronutrient consumption until other microbial requirements such as macronutrients or light become limiting, and additional iron no longer increases productivity. This feedback emerges in numerical simulations of the coupled marine cycles of macronutrients and iron that resolve the dynamic microbial production and loss of iron-chelating ligands. The model solutions resemble modern nutrient distributions only over a finite range of prescribed ligand source/sink ratios where the model ocean is driven to global-scale colimitation by micronutrients and macronutrients and global production is maximized. We hypothesize that a global-scale selection for microbial ligand cycling may have occurred to maintain "just enough" iron in the ocean.
Topics: Bacteria; Computer Simulation; Cyanobacteria; Feedback; Ferric Compounds; Iron; Iron Chelating Agents; Ligands; Micronutrients; Models, Biological; Nutrients; Oceans and Seas; Photochemistry; Seawater; Siderophores; Water Microbiology
PubMed: 32071221
DOI: 10.1073/pnas.1917277117 -
Molecules (Basel, Switzerland) Aug 2020This review focuses on the description of several examples of supramolecular assemblies of phthalocyanine derivatives differently functionalized and interfaced with... (Review)
Review
This review focuses on the description of several examples of supramolecular assemblies of phthalocyanine derivatives differently functionalized and interfaced with diverse kinds of chemical species for photo-induced phenomena applications. In fact, the role of different substituents was investigated in order to tune peculiar aggregates formation as well as, with the same aim, the possibility to interface these derivatives with other molecular species, as electron donor and acceptor, carbon allotropes, cyclodextrins, protein cages, drugs. Phthalocyanine photo-physical features are indeed really interesting and appealing but need to be preserved and optimized. Here, we highlight that the supramolecular approach is a versatile method to build up very complex and functional architectures. Further, the possibility to minimize the organization energy and to facilitate the spontaneous assembly of the molecules, in numerous examples, has been demonstrated to be more useful and performing than the covalent approach.
Topics: Electron Transport; Indoles; Isoindoles; Light; Photochemistry; Polymers; Thermodynamics
PubMed: 32824375
DOI: 10.3390/molecules25163742 -
Environmental Science and Pollution... Dec 2019
Topics: Photochemistry; Solar Energy; Sunlight
PubMed: 31867691
DOI: 10.1007/s11356-019-07334-w -
Angewandte Chemie (International Ed. in... Aug 2022My favorite example of science in everyday life is photochemistry, nature's most efficient way to store solar energy … My favorite way to spend a holiday is hiking in...
My favorite example of science in everyday life is photochemistry, nature's most efficient way to store solar energy … My favorite way to spend a holiday is hiking in polar regions far from everyone …" Find out more about Tomáš Slanina in his Introducing … Profile.
Topics: Photochemistry; Solar Energy
PubMed: 35796216
DOI: 10.1002/anie.202208779 -
Current Topics in Medicinal Chemistry 2021Cissus incisa is a Vitaceae with a pantropical distribution. In northern Mexico, its leaves have traditionally been used to treat skin infections, abscesses and tumors.... (Review)
Review
BACKGROUND
Cissus incisa is a Vitaceae with a pantropical distribution. In northern Mexico, its leaves have traditionally been used to treat skin infections, abscesses and tumors. Despite its medicinal uses, few studies have been reported.
OBJECTIVE
The objective of this study is to summarize the phytochemical and biological studies carried out so far on the leaves of C. incisa, since this part of the plant is the one frequently used, and awaken scientific interest towards the plant.
METHODS
Since C. incisa was an undocumented species, most of the information comes from reports of our research group. Databases, books, and websites were also consulted. The information collected was organized and presented in a synthesized way. Plant name was checked with the database "The Plant List".
RESULTS
171, 260, and 114 metabolites were identified by UHPLC-QFTOF-MS in the hexane, chloroform/ methanol, and aqueous extracts, respectively. Fatty acyls, sphingolipids, sterols, glycerolipids, prenol lipids, and terpenes are common metabolites found in these extracts. 2-(2´-hydroxydecanoyl amino)-1,3,4-hexadecanotriol-8-ene, 2,3-dihydroxypropyl tetracosanoate, β-sitosterol, β-sitosterol-D-glucopyranoside, α-amyrin-3-O-β-D-glucopyranoside were also isolated and characterized. Extracts, phytocompounds and semi-synthetic derivatives showed antimicrobial activity against multi-drug resistant bacteria and various cancer cell lines. Results from Perturbation- Theory-Machine Learning-Information-Fusion model (PTMLIF), molecular docking, and vesicular contents assay identified potential targets on the cell membrane, suggesting an antibacterial mechanism of action for ceramides from C. incisa leaves.
CONCLUSION
This review reports the efforts of the scientific community in authenticating species used in traditional medicine. Moreover, it gives a compendium of phytochemistry and the biological activities of the components from C. incisa leaves.
Topics: Anti-Bacterial Agents; Cissus; Humans; Medicine, Traditional; Molecular Docking Simulation; Photochemistry; Plant Extracts; Plant Leaves
PubMed: 34503406
DOI: 10.2174/1568026621666210909163612 -
Molecules (Basel, Switzerland) May 2020The use of light-activated chemical probes to study biological interactions was first discovered in the 1960s, and has since found many applications in studying diseases... (Review)
Review
The use of light-activated chemical probes to study biological interactions was first discovered in the 1960s, and has since found many applications in studying diseases and gaining deeper insight into various cellular mechanisms involving protein-protein, protein-nucleic acid, protein-ligand (drug, probe), and protein-co-factor interactions, among others. This technique, often referred to as photoaffinity labelling, uses radical precursors that react almost instantaneously to yield spatial and temporal information about the nature of the interaction and the interacting partner(s). This review focuses on the recent advances in chemical biology in the use of benzophenones and diazirines, two of the most commonly known light-activatable radical precursors, with a focus on the last three years, and is intended to provide a solid understanding of their chemical and biological principles and their applications.
Topics: Benzophenones; Diazomethane; Photoaffinity Labels; Photochemistry
PubMed: 32414020
DOI: 10.3390/molecules25102285 -
Chemical Reviews Dec 2021This review adds the bilin-binding phytochromes to the thematic issue "Optogenetics and Photopharmacology". The work is structured into two parts. We first outline the... (Review)
Review
This review adds the bilin-binding phytochromes to the thematic issue "Optogenetics and Photopharmacology". The work is structured into two parts. We first outline the photochemistry of the covalently bound tetrapyrrole chromophore and summarize relevant spectroscopic, kinetic, biochemical, and physiological properties of the different families of phytochromes. Based on this knowledge, we then describe the engineering of phytochromes to further improve these chromoproteins as photoswitches and review their employment in an ever-growing number of different optogenetic applications. Most applications rely on the light-controlled complex formation between the plant photoreceptor PhyB and phytochrome-interacting factors (PIFs) or C-terminal light-regulated domains with enzymatic functions present in many bacterial and algal phytochromes. Phytochrome-based optogenetic tools are currently implemented in bacteria, yeast, plants, and animals to achieve light control of a wide range of biological activities. These cover the regulation of gene expression, protein transport into cell organelles, and the recruitment of phytochrome- or PIF-tagged proteins to membranes and other cellular compartments. This compilation illustrates the intrinsic advantages of phytochromes compared to other photoreceptor classes, e.g., their bidirectional dual-wavelength control enabling instant ON and OFF regulation. In particular, the long wavelength range of absorption and fluorescence within the "transparent window" makes phytochromes attractive for complex applications requiring deep tissue penetration or dual-wavelength control in combination with blue and UV light-sensing photoreceptors. In addition to the wide variability of applications employing natural and engineered phytochromes, we also discuss recent progress in the development of bilin-based fluorescent proteins.
Topics: Animals; Bile Pigments; Light; Optogenetics; Photochemistry; Photoreceptor Cells; Phytochrome
PubMed: 34669383
DOI: 10.1021/acs.chemrev.1c00194 -
Chemical Reviews Jan 2022Geometrical → alkene isomerization is intimately entwined in the historical fabric of organic photochemistry and is enjoying a renaissance (Roth et al. ,... (Review)
Review
Geometrical → alkene isomerization is intimately entwined in the historical fabric of organic photochemistry and is enjoying a renaissance (Roth et al. , 1193-1207). This is a consequence of the fundamental stereochemical importance of -alkenes, juxtaposed with frustrations in thermal reactivity that are rooted in microscopic reversibility. Accessing excited state reactivity paradigms allow this latter obstacle to be circumnavigated by exploiting subtle differences in the photophysical behavior of the substrate and product chromophores: this provides a molecular basis for directionality. While direct irradiation is operationally simple, photosensitization via selective energy transfer enables augmentation of the alkene repertoire to include substrates that are not directly excited by photons. Through sustained innovation, an impressive portfolio of tailored small molecule catalysts with a range of triplet energies are now widely available to facilitate -thermodynamic and thermo-neutral isomerization reactions to generate -alkene fragments. This review is intended to serve as a practical guide covering the geometric isomerization of alkenes enabled by energy transfer catalysis from 2000 to 2020, and as a logical sequel to the excellent treatment by Dugave and Demange (. , 2475-2532). The mechanistic foundations underpinning isomerization selectivity are discussed together with induction models and rationales to explain the counterintuitive directionality of these processes in which very small energy differences distinguish substrate from product. Implications for subsequent stereospecific transformations, application in total synthesis, regioselective polyene isomerization, and spatiotemporal control of pre-existing alkene configuration in a broader sense are discussed.
Topics: Alkenes; Catalysis; Energy Transfer; Isomerism; Photochemistry
PubMed: 34449198
DOI: 10.1021/acs.chemrev.1c00324 -
Angewandte Chemie (International Ed. in... Dec 2022Enzymes have several advantages over conventional catalysts for organic synthesis. Over the last two decades, much effort has been made to further extend the scope of... (Review)
Review
Enzymes have several advantages over conventional catalysts for organic synthesis. Over the last two decades, much effort has been made to further extend the scope of biocatalytic reactions available to synthetic chemists, particularly by expanding the repertoire of enzymes for abiological transformations. In this regard, exciting new developments in the area of photobiocatalysis enable now the introduction of non-natural reactivity in enzymes to solve long-standing synthetic challenges. A recently described example from the Hyster group demonstrates in an unprecedented way how the combination of photochemistry with enzyme catalysis empowers the catalytic asymmetric construction of Csp -Csp bonds with high chemo- and enantioselectivity.
Topics: Stereoisomerism; Catalysis; Biocatalysis; Chemistry Techniques, Synthetic; Photochemistry; Enzymes
PubMed: 36239986
DOI: 10.1002/anie.202214313 -
Environmental Science and Pollution... Dec 2022Mismanagement of obsolete solid waste generates a massive deteriorating effect on the environment. There is a high level of open trash disposal contaminating its...
Mismanagement of obsolete solid waste generates a massive deteriorating effect on the environment. There is a high level of open trash disposal contaminating its neighboring water bodies. This despoliation trash causes an endangerment to the living environment. The waste management act is to hinder harmful effects on human beings, animals, plants, and their natural environment through the principles of waste prevention, waste processing, and waste disposal. Surface-enhanced Raman scattering (SERS) enhances the hazardous chemical sensing of environmental pollutants. To vigorously focus on the leaching of a couple of landfills in groundwater and surface water, an unusual combination of SERS-based poly vinyl thiol and silica-modified silver nanocomposites (PVT/SiO2@Ag NCs) was synthesized. The optical, crystalline, and structural properties of PVT/SiO@Ag NCs were described with UV-visible spectroscopy (UV-Vis), X-ray diffractometer (XRD), transmission electron microscope (TEM), and energy-dispersive X-ray analysis (EDX). The surface plasmon resonance (SPR) is detected at 403 nm from the PVT/SiO@Ag NPs. The average crystallite size of PVT/SiO @ Ag NCs is estimated using the Scherrer formula as 11 nm. The calculated specific surface area (SSA), strains, and dislocation densities demonstrate the improved mechanical properties of the substrate. The well-separated spherical shape of NPs is also observed, and the composition of silica and sulfur element in addition of Ag was confirmed by EDAX. Negatively charged SiO were bound strongly with the SH group and Ag NPs through electrostatic interaction mechanism as S-Ag-O-Si-O-Ag-S. SERS sensitivity is demonstrated by the prepared nanoparticles using an environmentally ignored leachate of municipal solid waste (MSW) and tannery waste (TW) landfill. PVT/SiO@Ag NCs has detected the presence of innards of MSW leachate viz., aromatic hydrocarbon, phenols, phthalates, and pesticide from the groundwater. Furthermore, the TW leachate compositions of benzenes, hydrocarbons, amines, and chromium VI were analytically identified. Also, the leaching of TW leachate was confirmed in the water samples referred. Hence, this study provides a novel SERS sensor of PVT/SiO@Ag NCs in the tile to detect and analyze environmentally ignored organic and inorganic compounds.
Topics: Humans; Solid Waste; Silicon Dioxide; Sulfhydryl Compounds; Photochemistry; Water
PubMed: 35861900
DOI: 10.1007/s11356-022-22058-0