Prebiotic potential of new sweeteners based on the simultaneous biosynthesis of galactooligosaccharides and enzymatically modified steviol glycosides.

Prebiotics are known for their health-promoting functions associated with the modulation of the colonic microbiota and the products of fermentation. Recently, single-pot syntheses of galactooligosaccharides in combination with steviol glycosides (mSG-GOS) have been developed. This work was conducted to evaluate their prebiotic effect by using faecal inoculum from healthy human donors during in vitro batch fermentations.

Bromine, iodine and sodium along the EAIIST traverse: Bulk and surface snow latitudinal variability.

During the East Antarctic International Ice Sheet Traverse (Eaiist, december 2019), in an unexplored part of the East Antarctic Plateau, snow samples were collected to expand our knowledge of the latitudinal variability of iodine, bromine and sodium as well as their relation in connection with emission processes and photochemical activation in this unexplored area. A total of 32 surface (0-5 cm) and 32 bulk (average of 1 m depth) samples were taken and analysed by Inductively Coupled Plasma Mass Spectrometry (ICP-MS). Our results show that there is no relevant latitudinal trend for bromine and sodium.

Understanding the fragmentation of glucose in mass spectrometry.

The fragmentation mechanism of D-glucose was investigated in detail by two different fragmentation techniques, namely, collision-induced dissociation (CID) and infrared multiphoton dissociation (IRMPD) using all six C-labeled isotopomers and H-labeled isotopomers. For both CID and IRMPD energy-resolved measurements were carried out. Individual fragmentation pathways were studied at MS and MS levels.

The salicylate 1,2-dioxygenase from Pseudaminobacter salicylatoxidans DSM 6986 is a bifunctional enzyme that inactivates the mycotoxin ochratoxin A by a novel amidohydrolase activity.

The salicylate 1,2-dioxygenase from the bacterium Pseudaminobacter salicylatoxidans DSM 6986 (PsSDO) is a versatile metalloenzyme that participates in the aerobic biodegradation of aromatic compounds, such as gentisates and salicylates. Surprisingly, and unrelated to this metabolic role, it has been reported that PsSDO may transform the mycotoxin ochratoxin A (OTA), a molecule that appears in numerous food products that results in serious biotechnological concern. In this work, we show that PsSDO, together with its dioxygenase activity, behaves as an amidohydrolase with a marked specificity for substrates containing a C-terminal phenylalanine residue, similar to OTA, although its presence is not an absolute requirement.

Atomic crystal structure and sugar specificity of a β-trefoil lectin domain from the ectomycorrhizal basidiomycete Laccaria bicolor.

Lectins from fruiting bodies are a diverse group of sugar-binding proteins from mushrooms that face the biologically relevant challenge of discriminating self- from non-self carbohydrate structures, therefore providing a basis for an innate defence system. Such a system entails both detection and destruction of invaders and/or feeders, and in contrast to more complex organisms with immense immune systems, these two functions normally rely on multitasking lectins, namely, lectins with different functional modules. Here, we present a novel fungal lectin, LBL, from the basidiomycete Laccaria bicolor.

Reply to the 'Comment on "Theoretical study of the NO radical reaction with CHClBr, CHICl, CHBrI, CHClBr, and CHClBr"' by C. J. Nielsen and Y. Tang, , 2022, , DOI: 10.1039/D2CP03013F.

In this Reply, we answer the main argument raised in the Comment about the energy of the NO radical and its influence in the reaction profiles of the reaction of the NO radical with CHClBr, CHICl, CHBrI, CHClBr, and CHClBr by C. J. Nielsen and Y.

Engineering a Highly Regioselective Fungal Peroxygenase for the Synthesis of Hydroxy Fatty Acids.

The hydroxylation of fatty acids is an appealing reaction in synthetic chemistry, although the lack of selective catalysts hampers its industrial implementation. In this study, we have engineered a highly regioselective fungal peroxygenase for the ω-1 hydroxylation of fatty acids with quenched stepwise over-oxidation. One single mutation near the Phe catalytic tripod narrowed the heme cavity, promoting a dramatic shift toward subterminal hydroxylation with a drop in the over-oxidation activity.

Insights into the Structure of the Highly Glycosylated Ffase from Enhance Its Biotechnological Potential.

β-fructofuranosidase is a highly glycosylated enzyme with broad substrate specificity that catalyzes the synthesis of 6-kestose and a mixture of the three series of fructooligosaccharides (FOS), fructosylating a variety of carbohydrates and other molecules as alditols. We report here its three-dimensional structure, showing the expected bimodular arrangement and also a unique long elongation at its N-terminus containing extensive O-glycosylation sites that form a peculiar arrangement with a protruding loop within the dimer. This region is not required for activity but could provide a molecular tool to target the dimeric protein to its receptor cellular compartment in the yeast.

Molecular recognition of a membrane-anchored HIV-1 pan-neutralizing epitope.

Antibodies against the carboxy-terminal section of the membrane-proximal external region (C-MPER) of the HIV-1 envelope glycoprotein (Env) are considered as nearly pan-neutralizing. Development of vaccines capable of producing analogous broadly neutralizing antibodies requires deep understanding of the mechanism that underlies C-MPER recognition in membranes. Here, we use the archetypic 10E8 antibody and a variety of biophysical techniques including single-molecule approaches to study the molecular recognition of C-MPER in membrane mimetics.

Identification of 1,2,3-triazolium salt-based inhibitors of Leishmania infantum trypanothione disulfide reductase with enhanced antileishmanial potency in cellulo and increased selectivity.

N-methylation of the triazole moiety present in our recently described triazole-phenyl-thiazole dimerization disruptors of Leishmania infantum trypanothione disulfide reductase (LiTryR) led to a new class of potent inhibitors that target different binding sites on this enzyme. Subtle structural changes among representative library members modified their mechanism of action, switching from models of classical competitive inhibition to time-dependent mixed noncompetitive inhibition. X-ray crystallography and molecular modeling results provided a rationale for this distinct behavior.

Verification: model-free phasing with enhanced predicted models in ARCIMBOLDO_SHREDDER.

Structure predictions have matched the accuracy of experimental structures from close homologues, providing suitable models for molecular replacement phasing. Even in predictions that present large differences due to the relative movement of domains or poorly predicted areas, very accurate regions tend to be present. These are suitable for successful fragment-based phasing as implemented in ARCIMBOLDO.

Urea versus fractional Er:YAG laser pretreatment of methylene blue photodynamic therapy in the treatment of moderate toenail onychomycosis: short- and medium-term effects.

Keratolytic properties of urea 40% have long time used for the treatment of onychomycosis. Fractional ablative lasers enhance the delivery of topically applied photosensitizers improving photodynamic therapy (PDT) efficacy. The aim of this study was to compare the short- and medium-term efficacy of a pretreatment with urea 40% and fractional Er:YAG (Fr Er:YAG) laser radiation before PDT mediated by methylene blue (MB) for moderate toenail onychomycosis.

Sea ice fluctuations in the Baffin Bay and the Labrador Sea during glacial abrupt climate changes.

Sea ice decline in the North Atlantic and Nordic Seas has been proposed to contribute to the repeated abrupt atmospheric warmings recorded in Greenland ice cores during the last glacial period, known as Dansgaard-Oeschger (D-O) events. However, the understanding of how sea ice changes were coupled with abrupt climate changes during D-O events has remained incomplete due to a lack of suitable high-resolution sea ice proxy records from northwestern North Atlantic regions. Here, we present a subdecadal-scale bromine enrichment (Br) record from the NEEM ice core (Northwest Greenland) and sediment core biomarker records to reconstruct the variability of seasonal sea ice in the Baffin Bay and Labrador Sea over a suite of D-O events between 34 and 42 ka.

Nucleus-translocated mitochondrial cytochrome c liberates nucleophosmin-sequestered ARF tumor suppressor by changing nucleolar liquid-liquid phase separation.

The regular functioning of the nucleolus and nucleus-mitochondria crosstalk are considered unrelated processes, yet cytochrome c (Cc) migrates to the nucleus and even the nucleolus under stress conditions. Nucleolar liquid-liquid phase separation usually serves the cell as a fast, smart mechanism to control the spatial localization and trafficking of nuclear proteins. Actually, the alternative reading frame (ARF), a tumor suppressor protein sequestered by nucleophosmin (NPM) in the nucleoli, is shifted out from NPM upon DNA damage.

eIF4G1 N-terminal intrinsically disordered domain is a multi-docking station for RNA, Pab1, Pub1, and self-assembly.

Yeast eIF4G1 interacts with RNA binding proteins (RBPs) like Pab1 and Pub1 affecting its function in translation initiation and stress granules formation. We present an NMR and SAXS study of the N-terminal intrinsically disordered region of eIF4G1 (residues 1-249) and its interactions with Pub1, Pab1 and RNA. The conformational ensemble of eIF4G1 shows an α-helix within the BOX3 conserved element and a dynamic network of fuzzy π-π and π-cation interactions involving arginine and aromatic residues.

Regulation of Lytic Machineries by the FtsEX Complex in the Bacterial Divisome.

The essential membrane complex FtsE/FtsX (FtsEX), belonging to the ABC transporter superfamily and widespread among bacteria, plays a relevant function in some crucial cell wall remodeling processes such as cell division, elongation, or sporulation. FtsEX plays a double role by recruiting proteins to the divisome apparatus and by regulating lytic activity of the cell wall hydrolases required for daughter cell separation. Interestingly, FtsEX does not act as a transporter but uses the ATPase activity of FtsE to mechanically transmit a signal from the cytosol, through the membrane, to the periplasm that activates the attached hydrolases.

Examining Topoisomers of a Snake-Venom-Derived Peptide for Improved Antimicrobial and Antitumoral Properties.

Ctn[15-34], the C-terminal section of crotalicidin (Ctn), a cathelicidin from a South American pit viper, is an antimicrobial and antitumoral peptide with remarkably longer stability in human serum than the parent Ctn. In this work, a set of topoisomers of both Ctn and Ctn[15-34], including the retro, enantio, and retroenantio versions, were synthesized and tested to investigate the structural requirements for activity. All topoisomers were as active as the cognate sequences against Gram-negative bacteria and tumor cells while slightly more toxic towards normal cells.

Photochemical and thermochemical pathways to S and polysulfur formation in the atmosphere of Venus.

Polysulfur species have been proposed to be the unknown near-UV absorber in the atmosphere of Venus. Recent work argues that photolysis of one of the (SO) isomers, cis-OSSO, directly yields S with a branching ratio of about 10%. If correct, this pathway dominates polysulfur formation by several orders of magnitude, and by addition reactions yields significant quantities of S, S, and S.

Structure-Function Insights into the Fungal -Chitinase Chit33 Depict its Mechanism on Chitinous Material.

Chitin is the most widespread amino renewable carbohydrate polymer in nature and the second most abundant polysaccharide. Therefore, chitin and chitinolytic enzymes are becoming more importance for biotechnological applications in food, health and agricultural fields, the design of effective enzymes being a paramount issue. We report the crystal structure of the plant-type -chitinase Chit33 from and its D165A/E167A-Chit33-(NAG) complex, which showed an extended catalytic cleft with six binding subsites lined with many polar interactions.

On the Speciation of Iodine in Marine Aerosol.

We have compiled and analyzed a comprehensive data set of field observations of iodine speciation in marine aerosol. The soluble iodine content of fine aerosol (PM) is dominated by soluble organic iodine (SOI; ∼50%) and iodide (∼30%), while the coarse fraction is dominated by iodate (∼50%), with nonnegligible amounts of iodide (∼20%). The SOI fraction shows an equatorial maximum and minima coinciding with the ocean "deserts," which suggests a link between soluble iodine speciation in aerosol and ocean productivity.

The Chemistry of Mercury in the Stratosphere.

Mercury, a global contaminant, enters the stratosphere through convective uplift, but its chemical cycling in the stratosphere is unknown. We report the first model of stratospheric mercury chemistry based on a novel photosensitized oxidation mechanism. We find two very distinct Hg chemical regimes in the stratosphere: in the upper stratosphere, above the ozone maximum concentration, Hg oxidation is initiated by photosensitized reactions, followed by second-step chlorine chemistry.