The long-chain flavodoxin FldX1 improves the biodegradation of 4-hydroxyphenylacetate and 3-hydroxyphenylacetate and counteracts the oxidative stress associated to aromatic catabolism in Paraburkholderia xenovorans.

BACKGROUND: Bacterial aromatic degradation may cause oxidative stress. The long-chain flavodoxin FldX1 of Paraburkholderia xenovorans LB400 counteracts reactive oxygen species (ROS). The aim of this study was to evaluate the protective role of FldX1 in P. xenovorans LB400 during the degradation of 4-hydroxyphenylacetate (4-HPA) and 3-hydroxyphenylacetate (3-HPA). METHODS: The functionality of FldX1 was evaluated in P. xenovorans p2-fldX1 that overexpresses FldX1. The effects of FldX1 on P. xenovorans were studied measuring growth on hydroxyphenylacetates, degradation of 4-HPA and 3-HPA, and ROS formation. The effects of hydroxyphenylacetates (HPAs) on the proteome (LC-MS/MS) and gene expression (qRT-PCR) were quantified. Bioaugmentation with strain p2-fldX1 of 4-HPA-polluted soil was assessed, measuring aromatic degradation (HPLC), 4-HPA-degrading bacteria, and plasmid stability. RESULTS: The exposure of P. xenovorans to 4-HPA increased the formation of ROS compared to 3-HPA or glucose. P. xenovorans p2-fldX1 showed an increased growth on 4-HPA and 3-HPA compared to the control strain WT-p2. Strain p2-fldX1 degraded faster 4-HPA and 3-HPA than strain WT-p2. Both WT-p2 and p2-fldX1 cells grown on 4-HPA displayed more changes in the proteome than cells grown on 3-HPA in comparison to glucose-grown cells. Several enzymes involved in ROS detoxification, including AhpC2, AhpF, AhpD3, KatA, Bcp, CpoF1, Prx1 and Prx2, were upregulated by hydroxyphenylacetates. Downregulation of organic hydroperoxide resistance (Ohr) and DpsA proteins was observed. A downregulation of the genes encoding scavenging enzymes (katE and sodB), and gstA and trxB was observed in p2-fldX1 cells, suggesting that FldX1 prevents the antioxidant response. More than 20 membrane proteins, including porins and transporters, showed changes in expression during the growth of both strains on hydroxyphenylacetates. An increased 4-HPA degradation by recombinant strain p2-fldX1 in soil microcosms was observed. In soil, the strain overexpressing the flavodoxin FldX1 showed a lower plasmid loss, compared to WT-p2 strain, suggesting that FldX1 contributes to bacterial fitness. Overall, these results suggest that recombinant strain p2-fldX1 is an attractive bacterium for its application in bioremediation processes of aromatic compounds. CONCLUSIONS: The long-chain flavodoxin FldX1 improved the capability of P. xenovorans to degrade 4-HPA in liquid culture and soil microcosms by protecting cells against the degradation-associated oxidative stress.

Structures of Toxic Advanced Glycation End-Products Derived from Glyceraldehyde, A Sugar Metabolite.

Advanced glycation end-products (AGEs) have recently been implicated in the onset/progression of lifestyle-related diseases (LSRDs); therefore, the suppression of AGE-induced effects may be used in both the prevention and treatment of these diseases. Various AGEs are produced by different biological pathways in the body. Glyceraldehyde (GA) is an intermediate of glucose and fructose metabolism, and GA-derived AGEs (GA-AGEs), cytotoxic compounds that accumulate and induce damage in mammalian cells, contribute to the onset/progression of LSRDs. The following GA-AGE structures have been detected to date: triosidines, GA-derived pyridinium compounds, GA-derived pyrrolopyridinium lysine dimers, methylglyoxal-derived hydroimidazolone 1, and argpyrimidine. GA-AGEs are a key contributor to the formation of toxic AGEs (TAGE) in many cells. The extracellular leakage of TAGE affects the surrounding cells via interactions with the receptor for AGEs. Elevated serum levels of TAGE, which trigger different types of cell damage, may be used as a novel biomarker for the prevention and early diagnosis of LSRDs as well as in evaluations of treatment efficacy. This review provides an overview of the structures of GA-AGEs.

Potential molecular mechanism of reuterin on the inhibition of Aspergillus flavus conidial germination: An in silico study.

Reuterin is a natural antifungal agent derived from certain strains of Limosilactobacillus reuteri. Our previous study revealed that 6 mM reuterin inhibited completely the conidial germination of aflatoxigenic Aspergillus flavus. This study investigated the potential molecular mechanism of reuterin in inhibiting A. flavus conidial germination, which was pre-assumed that it correlated to the inhibition of some essential enzyme activity involved in conidial germination, specifically 1,3-ß-glucan synthase, chitin synthase, and catalases (catalase, bifunctional catalase-peroxidase, and spore-specific catalase). The complex of 1,3-ß-glucan synthase and chitin synthase with reuterin had a lower binding affinity than that with the substrate. Conversely, the complex of catalases with reuterin had a higher binding affinity than that with the substrate. It was suggested that 1,3-ß-glucan synthase and chitin synthase tended to bind the substrate rather than bind reuterin. In contrast, catalases tended to bind reuterin rather than bind the substrate. Therefore, reuterin could be a potential inhibitor of catalases but may not be an inhibitor of 1,3-ß-glucan synthase and chitin synthase. In this in silico study, we predicted that the potential molecular mechanism of reuterin in inhibiting A. flavus conidial germination was due to the inhibition of catalases activities by competitively binding to the enzymes active sites, thus resulting in the accumulation of reactive oxygen species in cells, leading to cells damage. PRACTICAL APPLICATION: This in silico study revealed that reuterin is a potential inhibitor of catalases in A. flavus, thereby interfering with the antioxidant system during conidial germination. This finding shows that reuterin can be used as an antifungal agent in food or agricultural products, inhibiting conidial germination completely.

Development of a Highly Selective NAD+ -Dependent Glyceraldehyde Dehydrogenase and its Application in Minimal Cell-Free Enzyme Cascades.

Anthropogenic climate change has been caused by over-exploitation of fossil fuels and CO2 emissions. To counteract this, the chemical industry has shifted its focus to sustainable chemical production and the valorization of renewable resources. However, the biggest challenges in biomanufacturing are technical efficiency and profitability. In our minimal cell-free enzyme cascade generating pyruvate as the central intermediate, the NAD+ -dependent, selective oxidation of D-glyceraldehyde was identified as a key reaction step to improve the overall cascade flux. Successive genome mining identified one candidate enzyme with 24-fold enhanced activity and another whose stability is unaffected in 10 % (v/v) ethanol, the final product of our model cascade. Semi-rational engineering improved the substrate selectivity of the enzyme up to 21-fold, thus minimizing side reactions in the one-pot enzyme cascade. The final biotransformation of D-glucose showed a continuous linear production of ethanol (via pyruvate) to a final titer of 4.9 % (v/v) with a molar product yield of 98.7 %. Due to the central role of pyruvate in diverse biotransformations, the optimized production module has great potential for broad biomanufacturing applications.

A Novel Approach: Investigating the Intracellular Clearance Mechanism of Glyceraldehyde-Derived Advanced Glycation End-Products Using the Artificial Checkpoint Kinase 1 d270KD Mutant as a Substrate Model.

Advanced glycation end-products (AGEs), formed through glyceraldehyde (GA) as an intermediate in non-enzymatic reactions with intracellular proteins, are cytotoxic and have been implicated in the pathogenesis of various diseases. Despite their significance, the mechanisms underlying the degradation of GA-derived AGEs (GA-AGEs) remain unclear. In the present study, we found that N-terminal checkpoint kinase 1 cleavage products (CHK1-CPs) and their mimic protein, d270WT, were degraded intracellularly post-GA exposure. Notably, a kinase-dead d270WT variant (d270KD) underwent rapid GA-induced degradation, primarily via the ubiquitin-proteasome pathway. The high-molecular-weight complexes formed by the GA stimulation of d270KD were abundant in the RIPA-insoluble fraction, which also contained high levels of GA-AGEs. Immunoprecipitation experiments indicated that the high-molecular-weight complexes of d270KD were modified by GA-AGEs and that p62/SQSTM1 was one of its components. The knockdown of p62 or treatment with chloroquine reduced the amount of high-molecular-weight complexes in the RIPA-insoluble fraction, indicating its involvement in the formation of GA-AGE aggregates. The present results suggest that the ubiquitin-proteasome pathway and p62 play a role in the degradation and aggregation of intracellular GA-AGEs. This study provides novel insights into the mechanisms underlying GA-AGE metabolism and may lead to the development of novel therapeutic strategies for diseases associated with the accumulation of GA-AGEs.

A strategic tool to improve the study of molecular determinants of Alzheimer's disease: The role of glyceraldehyde.

Alzheimer's disease (AD) is the most prevalent form of dementia and is characterized by progressive neurodegeneration leading to severe cognitive, memory, and behavioral impairments. The onset of AD involves a complex interplay among various factors, including age, genetics, chronic inflammation, and impaired energy metabolism. Despite significant efforts, there are currently no effective therapies capable of modifying the course of AD, likely owing to an excessive focus on the amyloid hypothesis and a limited consideration of other intracellular pathways. In the present review, we emphasize the emerging concept of AD as a metabolic disease, where alterations in energy metabolism play a critical role in its development and progression. Notably, glucose metabolism impairment is associated with mitochondrial dysfunction, oxidative stress, Ca2+ dyshomeostasis, and protein misfolding, forming interconnected processes that perpetuate a detrimental self-feeding loop sustaining AD progression. Advanced glycation end products (AGEs), neurotoxic compounds that accumulate in AD, are considered an important consequence of glucose metabolism disruption, and glyceraldehyde (GA), a glycolytic intermediate, is a key contributor to AGEs formation in both neurons and astrocytes. Exploring the impact of GA-induced glucose metabolism impairment opens up exciting possibilities for creating an easy-to-handle in vitro model that recapitulates the early stage of the disease. This model holds great potential for advancing the development of novel therapeutics targeting various intracellular pathways implicated in AD pathogenesis. In conclusion, looking beyond the conventional amyloid hypothesis could lead researchers to discover promising targets for intervention, offering the possibility of addressing the existing medical gaps in AD treatment.

Metabolite interactions in the bacterial Calvin cycle and implications for flux regulation.

Metabolite-level regulation of enzyme activity is important for microbes to cope with environmental shifts. Knowledge of such regulations can also guide strain engineering for biotechnology. Here we apply limited proteolysis-small molecule mapping (LiP-SMap) to identify and compare metabolite-protein interactions in the proteomes of two cyanobacteria and two lithoautotrophic bacteria that fix CO2 using the Calvin cycle. Clustering analysis of the hundreds of detected interactions shows that some metabolites interact in a species-specific manner. We estimate that approximately 35% of interacting metabolites affect enzyme activity in vitro, and the effect is often minor. Using LiP-SMap data as a guide, we find that the Calvin cycle intermediate glyceraldehyde-3-phosphate enhances activity of fructose-1,6/sedoheptulose-1,7-bisphosphatase (F/SBPase) from Synechocystis sp. PCC 6803 and Cupriavidus necator in reducing conditions, suggesting a convergent feed-forward activation of the cycle. In oxidizing conditions, glyceraldehyde-3-phosphate inhibits Synechocystis F/SBPase by promoting enzyme aggregation. In contrast, the glycolytic intermediate glucose-6-phosphate activates F/SBPase from Cupriavidus necator but not F/SBPase from Synechocystis. Thus, metabolite-level regulation of the Calvin cycle is more prevalent than previously appreciated.

Production of reuterin by Lactobacillus coryniformis and its antimicrobial activities.

Reuterin is a broad-spectrum antimicrobial substance produced by lactic acid bacteria, and most previous studies have reported that reuterin is only produced under anaerobic conditions. If there are lactic acid bacteria that also produce it under aerobic conditions, it could be applied to fermented foods. In this study, it was found that Lactobacillus coryniformis WBB05 showed optimal reuterin production (123 mM reuterin from 200 mM glycerol) when incubated aerobically at 20°C. Furthermore, the minimum inhibitory concentration (MIC) of reuterin was determined for starter lactic acid bacteria strains and cheese moulds. MIC toward Penicillium camemberti was 0.125 mM and the white mould starter was much more sensitive than other moulds.

An artificial multienzyme cascade for the whole-cell synthesis of rare ketoses from glycerol.

PURPOSE: In our previous study, we constructed a one-pot multi-enzyme system for rare ketoses synthesis based on L-rhamnulose-1-phosphate aldolase (RhaD) from accessible glycerol in vitro. To eliminate tedious purification of enzymes, a facile Escherichia coli whole-cell cascade platform was established in this study. METHODS: To enhance the conversion rate, the reaction conditions, substrate concentrations and expressions of related enzymes were extensively optimized. RESULTS: The biosynthetic route for the cascade synthesis of rare ketoses in whole cells was successfully constructed and three rare ketoses including D-allulose, D-sorbose and L-fructose were produced using glycerol and D/L-glyceraldehyde (GA). Under optimized conditions, the conversion rates of rare ketoses were 85.0% and 93.0% using D-GA and L-GA as the receptor, respectively. Furthermore, alditol oxidase (AldO) was introduced to the whole-cell system to generate D-GA from glycerol, and the total production yield of D-sorbose and D-allulose was 8.2 g l-1 only from the sole carbon source glycerol. CONCLUSION: This study demonstrates a feasible and cost-efficient method for rare sugars synthesis and can also be applied to the green synthesis of other value-added chemicals from glycerol.

Measuring the Oxidation State and Enzymatic Activity of Glyceraldehyde Phosphate Dehydrogenase (GAPDH).

Glyceraldehyde phosphate dehydrogenase (GAPDH) is a highly conserved, essential, and abundant enzyme that catalyzes a rate-determining step of glycolysis. GAPDH catalyzes the nicotinamide adenine dinucleotide (NAD+)- and inorganic phosphate-dependent oxidation and phosphorylation of glyceraldehyde phosphate (GAP) to form 1,3-bisphosphoglycerate (BPG). As part of its mechanism of action, GAPDH employs a redox-sensitive cysteine that serves as a nucleophile to form a covalent adduct with GAP in order to set-up subsequent oxidation and phosphorylation steps. As a result of the redox sensitivity of the active site cysteine residue, GAPDH is susceptible to oxidative inactivation by oxidants such as hydrogen peroxide (H2O2). Indeed, numerous studies have demonstrated that oxidative inactivation of GAPDH has important metabolic consequences for adaptation to life in air and oxidative stress since decreased GAPDH activity results in the rerouting of carbon flux away from glycolysis and toward the pentose phosphate pathway to produce the key cellular reductant and antioxidant, NADPH. Thus, the ability to probe GAPDH oxidation and activity provides an important snapshot of the intracellular redox environment and glycolytic flux. Herein, we describe methods to measure reduced and oxidized GAPDH using thiol alkylation assays as well as GAPDH enzymatic activity.

Effects of organic and inorganic nitrogen sources on the transcriptome of gellan gum biosynthesis by Sphingomonas paucimobilis.

AIM: Investigate the effects of different nitrogen sources on the metabolic characteristics of Sphingomonas paucimobilis during gellan gum (GG) production was helpful for developing optimized conditions that are widely applicable to all GG production processes. METHODS AND RESULTS: We compared the effects of organic nitrogen (ON) and inorganic nitrogen (IN) sources during GG production using transcriptome sequencing. Our results showed that compared with the IN source, the ON source effectively improved the cell number and GG production of S. paucimobilis during fermentation. There were significant differences in gene transcription levels between the ON and IN groups at different fermentation times. CONCLUSIONS: The transcriptional levels of multiple genes in the pathways from α-D-glucose-1P to glyceraldehyde-3P were reduced in the ON group, whereas those of multiple genes in the pathways from glyceraldehyde-3P to acetyl-CoA were significantly enhanced in the ON group after 12 h of fermentation. The transcription levels of multiple genes participating in the citrate cycle and upstream of fatty acid metabolism pathways were significantly enhanced in the ON group after 12 h of fermentation. Except for the transcripts per million (TPMs) of pgm and rfbA genes in ON, which were significantly higher than those in IN at 12 h after fermentation, the TPMs of the majority of genes in ON were significantly lower than those in IN. The transcription levels of genes participating in the transformation of N-acetyl-D-glucosamine (GlcNAc) to UDP-N-acetyl-alpha-D-glucosamine (UDP-GlcNAc) were enhanced in the ON group during the fermentation process.

Prediagnostic serum glyceraldehyde-derived advanced glycation end products and mortality among colorectal cancer patients.

Glyceraldehyde-derived advanced glycation end products (glycer-AGEs) could contribute to colorectal cancer development and progression due to their pro-oxidative and pro-inflammatory properties. However, the association of glycer-AGEs with mortality after colorectal cancer diagnosis has not been previously investigated. Circulating glycer-AGEs were measured by competitive ELISA. Multivariable Cox proportional hazards models were used to calculate hazard ratios (HRs) and corresponding 95% confidence intervals (CIs) for associations of circulating glycer-AGEs concentrations with CRC-specific and all-cause mortality among 1034 colorectal cancer (CRC) cases identified within the European Prospective Investigation into Cancer and Nutrition (EPIC) study between 1993 and 2013. During a mean of 48 months of follow-up, 529 participants died (409 from CRC). Glycer-AGEs were statistically significantly positively associated with CRC-specific (HRQ5 vs Q1  = 1.53, 95% CI: 1.04-2.25, Ptrend  = .002) and all-cause (HRQ5 vs Q1  = 1.62, 95% CI: 1.16-2.26, Ptrend  < .001) mortality among individuals with CRC. There was suggestion of a stronger association between glycer-AGEs and CRC-specific mortality among patients with distal colon cancer (per SD increment: HRproximal colon  = 1.02, 95% CI: 0.74-1.42; HRdistal colon  = 1.51, 95% CI: 1.20-1.91; Peffect modification  = .02). The highest HR was observed among CRC cases in the highest body mass index (BMI) and glycer-AGEs category relative to lowest BMI and glycer-AGEs category for both CRC-specific (HR = 1.78, 95% CI: 1.02-3.01) and all-cause mortality (HR = 2.15, 95% CI: 1.33-3.47), although no statistically significant effect modification was observed. Our study found that prediagnostic circulating glycer-AGEs are positively associated with CRC-specific and all-cause mortality among individuals with CRC. Further investigations in other populations and stratifying by tumor location and BMI are warranted.

Toxic Advanced Glycation End-Products-Dependent Alzheimer's Disease- Like Alternation in the Microtubule System.

Type 2 diabetes mellitus (T2DM) is a risk factor for Alzheimer's Disease (AD). However, the detailed mechanism underlying T2DM-related AD remains unknown. In DM, many types of advanced glycation end-products (AGEs) are formed and accumulated. In our previous study, we demonstrated that Glyceraldehyde (GA)-derived Toxic Advanced Glycation End-products (Toxic AGEs, TAGE) strongly showed cytotoxicity against neurons and induced similar alterations to those observed in AD. Further, GA induced dysfunctional neurite outgrowth via TAGE-ß-- tubulin aggregation, which resulted in the TAGE-dependent abnormal aggregation of ß-tubulin and tau phosphorylation. Herein, we provide a perspective on the possibility that T2DM increases the probability of AD onset and accelerates its progression.

Metagenomic insights into the symbiotic relationship in anammox consortia at reduced temperature.

Anammox as a promising biological nitrogen removal technology has attracted much attention. However, cold temperature would limit its wide application and little is known about the microbial interactions between anammox bacteria (AnAOB) and heterotrophic bacteria at cold temperature. Here, we observed reduced temperature (25-15 °C) promoted the secretion of EPS and thus stimulated bigger size of granular sludge in a laboratory-scale anammox reactor. We further combined co-occurrence network analysis and genome-centered metagenomics to explore the potential interactions between AnAOB and heterotrophic bacteria. Network analysis suggested 22 out of 25 positively related species were reported as definite heterotrophic bacteria in subnetwork of AnAOB. Genome-centered metagenomics analysis yielded 23 metagenomic assembly genomes (MAGs), and we found that Acidobacteriota-affiliated bacteria could biosynthesize most polysaccharides (PS) precursors and contain the most glycosyltransferases and transporters to facilitate exopolysaccharides biosynthesis, together with partial PS precursors produced by AnAOB. AMX1 as the only anammox genome could synthesize most amino acids and cross feed with some heterotrophs to affect the extracellular protein function. Additionally, Bacteroidota, Planctomycetota, Chloroflexota, and Proteobacteria could contribute folate and molybdopterin cofactor for AMX1 to benefit their activity and growth. Superphylum Patescibacteria could survive by cross-feeding with AnAOB and heterotrophic organisms about organic compounds (Glyceraldehyde-3P and lactate). These cross-feedings maintained the stability of anammox reactor performance and emphasize the importance of heterotrophs in anammox system at reduced temperature.

Crystal structure and biochemical analysis suggest that YjoB ATPase is a putative substrate-specific molecular chaperone.

AAA+ ATPases are ubiquitous proteins associated with most cellular processes, including DNA unwinding and protein unfolding. Their functional and structural properties are typically determined by domains and motifs added to the conserved ATPases domain. Currently, the molecular function and structure of many ATPases remain elusive. Here, we report the crystal structure and biochemical analyses of YjoB, a Bacillus subtilis AAA+ protein. The crystal structure revealed that the YjoB hexamer forms a bucket hat-shaped structure with a porous chamber. Biochemical analyses showed that YjoB prevents the aggregation of vegetative catalase KatA and gluconeogenesis-specific glyceraldehyde-3 phosphate dehydrogenase GapB but not citrate synthase, a conventional substrate. Structural and biochemical analyses further showed that the internal chamber of YjoB is necessary for inhibition of substrate aggregation. Our results suggest that YjoB, conserved in the class Bacilli, is a potential molecular chaperone acting in the starvation/stationary phases of B. subtilis growth.

Pt1 enhanced C-H activation synergistic with Ptn catalysis for glycerol cascade oxidation to glyceric acid.

The selective oxidation of glycerol to glyceric acid, an important value-added reaction from polyols, is a typical cascade catalytic process. It is still of great challenge to simultaneously achieve high glycerol activity and glyceric acid selectivity, suffering from either deep oxidation and C-C cleavage or poor oxidation efficiency from glyceraldehyde to glyceric acid. Herein, this work, inspired by nature, proposes a cascade synergistic catalysis strategy by atomic and low-coordinated cluster Pt on well-defined Cu-CuZrOx, which involves enhanced C-H activation on atomic Pt1 and O-H activation on cluster Ptn in the oxidation of glycerol to glyceraldehyde, and cluster Ptn for C=O activation followed by O-H insertion and atomic Pt1 for C-H activation in the tandem oxidation of glyceraldehyde to glyceric acid. The enhanced C-H activation in the cascade process by atomic Pt1 is revealed to be essential for the high glycerol activity (90.0±0.1%) and the glyceric acid selectivity (80.2±0.2%).

Triosephosphate Isomerase and Its Product Glyceraldehyde-3-Phosphate Are Involved in the Regulatory Mechanism That Suppresses Exit from the Quiescent State in Yeast Cells.

Cells of the budding yeast Saccharomyces cerevisiae form spores or stationary cells upon nutrient starvation. These quiescent cells are known to resume mitotic growth in response to nutrient signals, but the mechanism remains elusive. Here, we report that quiescent yeast cells are equipped with a negative regulatory mechanism which suppresses the commencement of mitotic growth. The regulatory process involves a glycolytic enzyme, triosephosphate isomerase (Tpi1), and its product, glyceraldehyde-3-phosphate (GAP). GAP serves as an inhibitory signaling molecule; indeed, the return to growth of spores or stationary cells is suppressed by the addition of GAP even in nutrient-rich growth media, though mitotic cells are not affected. Reciprocally, dormancy is abolished by heat treatment because of the heat sensitivity of Tpi1. For example, spores commence germination merely upon heat treatment, which indicates that the negative regulatory mechanism is actively required for spores to prevent premature germination. Stationary cells of Candida glabrata are also manipulated by heat and GAP, suggesting that the regulatory process is conserved in the pathogenic yeast. IMPORTANCE Our results suggest that, in quiescent cells, nutrient signals do not merely provoke a positive regulatory process to commence mitotic growth. Exit from the quiescent state in yeast cells is regulated by balancing between the positive and negative signaling pathways. Identifying the negative regulatory pathway would provide new insight into the regulation of the transition from the quiescent to the mitotic state. Clinically, quiescent cells are problematic because they are resistant to environmental stresses and antibiotics. Given that the quiescent state is modulated by manipulation of the negative regulatory mechanism, understanding this process is important not only for its biological interest but also as a potential target for antifungal treatment.

Selective Oxidation of Glycerol into Formic Acid by Photogenerated Holes and Superoxide Radicals.

Photocatalysis is a promising technology for conversion of the glycerol into formic acid, but photocatalytic oxidation of C-C bonds in glycerol exhibits poor selectivity towards formic acid because the photogenerated radicals (e.g., hydroxyl radicals) further oxidize formic acid to CO2 . In this work, a synergy of photogenerated holes and superoxide radicals that achieved the selective oxidation of glycerol into formic acid over the TiO2 catalyst was revealed. The charge separation of pristine TiO2 was improved with the aid of oxygen, which resulted in efficient hole oxidation of the C-C bonds in glycerol to formic acid. Surface active species were controlled to prevent being converted to hydroxyl radicals on TiO2 by controlling the oxygen and water contents, which solved the problem of formic acid peroxidation without sophisticated catalyst modifications. Mechanism studies suggested that glyceraldehyde and glycolaldehyde were the intermediates to generate formic acid. This work provides a green and efficient approach to produce formic acid as a liquid hydrogen carrier from bio-based alcohols.

Glyceraldehyde-derived advanced glycation end-products are associated with left ventricular ejection fraction and brain natriuretic peptide in patients with diabetic adverse cardiac remodeling.

Objectives: Glyceraldehyde-derived advanced glycation end-products (Glycer-AGEs) have a strong binding affinity for their cognate receptor and elicit oxidative stress and inflammation. However, it remains unknown whether the levels of Glycer-AGEs correlate with the severity of cardiac function and heart failure in patients with diabetic adverse cardiac remodeling (DbCR). Fourteen heart failure patients with type 2 diabetes mellitus (DM) without other cardiac disorders (DbCR group) were enrolled. Another 14 patients with idiopathic dilated cardiomyopathy (DCM) without DM were served as a control (DCM group). All patients were assessed for serum Glycer-AGEs, nitrotyrosine (NT), and tumor necrosis factor alpha (TNFα) and for plasma brain natriuretic peptide (BNP). The left ventricular ejection fraction (LVEF) was evaluated by echocardiography. Results: The mean serum levels of Glycer-AGEs, NT, and TNFα in the DbCR group were significantly higher than those in the DCM group (for Glycer-AGEs, p = .0073; for NT, p = .005; for TNFα, p < .0001, respectively). In the patients with DbCR, the levels of serum Glycer-AGEs and TNFα were closely associated with LVEF and BNP values. Conclusions: Both Glycer-AGEs and TNFα showed close associations with LVEF and the levels of BNP in patients with DbCR. Glycer-AGEs and TNFα may play a pathological role in the development of DbCR.

Dynamics of Reactive Carbonyl Species in Pea Root Nodules in Response to Polyethylene Glycol (PEG)-Induced Osmotic Stress.

Drought dramatically affects crop productivity worldwide. For legumes this effect is especially pronounced, as their symbiotic association with rhizobia is highly-sensitive to dehydration. This might be attributed to the oxidative stress, which ultimately accompanies plants' response to water deficit. Indeed, enhanced formation of reactive oxygen species in root nodules might result in up-regulation of lipid peroxidation and overproduction of reactive carbonyl compounds (RCCs), which readily modify biomolecules and disrupt cell functions. Thus, the knowledge of the nodule carbonyl metabolome dynamics is critically important for understanding the drought-related losses of nitrogen fixation efficiency and plant productivity. Therefore, here we provide, to the best of our knowledge, for the first time a comprehensive overview of the pea root nodule carbonyl metabolome and address its alterations in response to polyethylene glycol-induced osmotic stress as the first step to examine the changes of RCC patterns in drought treated plants. RCCs were extracted from the nodules and derivatized with 7-(diethylamino)coumarin-3-carbohydrazide (CHH). The relative quantification of CHH-derivatives by liquid chromatography-high resolution mass spectrometry with a post-run correction for derivative stability revealed in total 194 features with intensities above 1 × 105 counts, 19 of which were down- and three were upregulated. The upregulation of glyceraldehyde could accompany non-enzymatic conversion of glyceraldehyde-3-phosphate to methylglyoxal. The accumulation of 4,5-dioxovaleric acid could be the reason for down-regulation of porphyrin metabolism, suppression of leghemoglobin synthesis, inhibition of nitrogenase and degradation of legume-rhizobial symbiosis in response to polyethylene glycol (PEG)-induced osmotic stress effect. This effect needs to be confirmed with soil-based drought models.