Biochemical Transformations Research Articles

Evaluation of certain pollutants generation inside municipal solid waste landfills

Municipal solid waste disposal sites act as sources of secondary pollution of the environment with waste destruction products that undergo further chemical and biochemical transformations. The research deals with the issues of quantitative assessment of greenhouse gases and persistent organic pollutants formation within municipal solid waste landfills. It uses such methods as mathematical models of pollutants formation inside a municipal solid waste landfill body, namely methane and persistent organic pollutants formation. Bioorganic substance forming the major part of municipal solid waste generates methane, carbon dioxide and other compounds; presence of chlorine in various compounds included in the composition of waste causes unintentional formation of persistent organic pollutants, in particular PCDD/F. The article presents the results of measurements of methane formation (according to the National Gas Formation Model), carbon dioxide and non-methane volatile organic compounds formation (according to the LandGEM model) with relation to the conditions of the municipal solid waste landfill «Dalnytsky Kariery» that accepts waste from the Odesa industrial-and-urban agglomeration. It shows the municipal solid waste landfill as a significant source of greenhouse gases the amount of which increases rapidly under the conditions of long-term operation and constant delivery of waste. The discrepancy in the results of methane formation measurements indicates the need to adapt the LandGEM model that matches the Ukrainian conditions. It would allow determining a wide range of atmospheric polluting substances. The author's design determines the formation of persistent organic pollutants as exemplified by PCDD/F. The measurements showed that landfills act as a significant source of unintentional formation of PCDD/F, 99% of which accumulate inside a landfill itself. They also indicated that, under the conditions of a constant delivery of waste to a landfill, there is a rapid increase in the amount of PCDD/F formed, even with consideration of the half-life period. The landfill itself is considered as a main source of unintentional formation of PCDD/F within the whole Odesa agglomeration.

PHOTOSENSITIVE EFFECT OF THE BIOCHEMICAL AND ECONOMIC TRAITS OF Bombyx mori L.

The silkworm is by nature very delicate and sensitive to environmental conditions. The ecological factors, chiefly temperature, humidity and light during rearing show significant effect on growth larvae and finally cocoon crop quality. Silkworms are photosensitive and they have a tendency to crawl towards dim light. They do not like either strong light or complete darkness. In this way, based on various exposures of light on the effect of biochemical content and economic traits of silkworm were recorded. Biochemical content such as protein is highly essential for insects. The intracellular transport of the silk protein is dependent on hydrophobicity or hydrophilicity of the amino acid residues of the heavy and light chain of the silk protein and the haemolymph is the only extracellular fluid of insects with diverse functions and serves as reservoir for the products required for every physiological activity of the insect body, thus changes in the composition of haemolymph reflect the physiological and biochemical transformations taking place in the insect tissue. In this way of study, effect of light on biochemical content such as protein and carbohydrate of haemolyph and silk gland are significantly increased. The protein content was high in the haemolymph (17.48%) when the larvae exposed to 5 watt light and silk gland (66.67%) in 3 watt exposure group but fat body (44.33 %) when the larvae exposed to 8 watt. The carbohydrate content of haemolymph (35.54 %), silk gland (12.85%) and fat body (57.26 %) were significantly increased in 3 watt exposure group. In this findings, biochemical content had direct relation to economic traits of B. mori. The cocoon characters such as cocoon weight (28.42 per cent), pupal weight (20.9 per cent), shell weight (71 per cent) and shell ratio (33.48 per cent) were significantly increased in the 3 watt exposed group.

Fate of Sulfate in Municipal Wastewater Treatment Plants and Its Effect on Sludge Recycling as a Fuel Source

Wastewater sludge is used as an alternative fuel due to its high organic content and calorific value. However, influent characteristics and operational practices of wastewater treatment plants (WWTPs) can increase the sulfur content of sludge, devaluing it as a fuel. Thus, we investigated the biochemical mechanisms that elevate the sulfur content of sludge in a full-scale industrial WWTP receiving wastewater of the textile dyeing industry and a domestic WWTP by monitoring the sulfate, sulfur, and iron contents and the biochemical transformation of sulfate to sulfur in the wastewater and sludge treatment streams. A batch sulfate reduction rate test and microbial 16S rRNA and dsrB gene sequencing analyses were applied to assess the potential and activity of sulfate-reducing bacteria and their effect on sulfur deposition. This study indicated that the primary clarifier and anaerobic digester prominently reduced sulfate concentration through biochemical sulfate reduction and iron–sulfur complexation under anaerobic conditions, from 1247 mg/L in the influent to 6.2~59.8 mg/L in the industrial WWTP and from 46.7 mg/L to 0~0.8 mg/L in the domestic WWTPs. The anaerobic sludge, adapted in the high sulfate concentration of the industrial WWTP, exhibited a two times higher specific sulfate reduction rate (0.13 mg SO42−/gVSS/h) and sulfur content (3.14% DS) than the domestic WWTP sludge. Gene sequencing analysis of the population structure of common microbes and sulfate-reducing bacteria indicated the diversity of microorganisms involved in biochemical sulfate reduction in the sulfur cycle, supporting the data revealed by chemical analysis and batch tests.

Soil Organic Matter of Tidal Marsh Permafrost-Affected Soils of Kolyma Lowland

Soils of the Arctic sea coasts are one of the least studied due to the complex logistical accessibility of the region, as well as the severe climatic conditions. The genesis of these soils is determined by several factors of soil formation simultaneously—cryogenesis, the influence of river alluvial processes, as well as the tidal influence of the sea. The paper presents data on the morphological structure of soils formed on the seacoast of the East-Siberian Sea (Kolyma Lowland, North Yakutia). Under the influence of cryogenesis and sea water tidal input, marsh soils are formed, with a relatively high level of salinity and the development of gleyization. Autochthonous and allochthonous soil organic matter play a leading role in marsh soil formation here, including the possible accumulation and biochemical transformation of incoming pollutants (e.g., hydrocarbons). The main objective of the study was to evaluate the soil organic matter genesis and alteration under the influence of tidal processes in coastal permafrost-affected soils as well as to obtain the previously unknown characteristics of the structural and elemental composition of different fractions of organic matter. The elemental composition and 13C NMR spectroscopy of humic acids were analyzed. It was revealed that humic acids extracted from the studied marsh soils accumulate up to 50% C and 4% N. Active processes of dehydrogenation are noted in HAs molecules, which indicates a relatively low degree of aliphatic structure development. According to 13C NMR spectroscopy, it was revealed that up to 45% of aromatic structural fragments accumulate in marsh soils, indicating a relatively high degree of organic matter stabilization and resistance to biodegradation.

Recovery of Energy and Nutrients from Mycotoxin-Contaminated Food Products through Biological Treatments in a Circular Economy Perspective: A Review

Mycotoxins’ contamination of food products is a well-known issue that is gaining interest nowadays due to increasing contaminations that are also related to climate change. In this context, and considering the principles of Circular Economy, finding robust and reliable strategies for the decontamination and valorisation of mycotoxin-contaminated products becomes mandatory. Anaerobic digestion (AD) and composting appear as promising biological treatments to degrade mycotoxins and allow for recovering energy (i.e., biogas production) and materials (i.e., nutrients from digestate and/or compost). The aim of the present paper was to carry out an organic revision of the state of the art of energy and materials recovery from mycotoxin-contaminated food products through biological treatments, highlighting results and research gaps. Both processes considered were not generally affected by the contamination of the feedstocks, proving that these compounds do not affect process stability. Mycotoxins were highly removed due to the concurrence of microbiological and physical agents in AD and composting. From the literature review, emerged the points that still need to be addressed before considering large scale application of these processes, which are (i) to deepen the knowledge of biochemical transformations of mycotoxins during the processes, (ii) to assess the fate of mycotoxins’ residues and metabolites in soil once digestate/compost are applied, (iii) to evaluate and optimize the integration of AD and composting in order to increase the environmental and economical sustainability of the processes, and (iv) to update legislation and regulations to allow the agricultural reuse of organic fertilizers obtained from contaminated feedstocks.

Variability of the Carbon Isotope Composition of Peat-Forming Plants during the Biochemical Transformation

In this study, we describe the variation in δ13C value in the litter of two species of peat-forming plants: Sphagnum fuscum and Eriophorum vaginatum, during 3 years of field decomposition in oligotrophic bog ecosystems drained for the purpose of forest melioration and fire affected and at the stage of post-pyrogenic restoration. Litterbags were periodically retrieved in the autumn and the δ13C value in the residual litter was related to mass loss, litter chemistry, and hydrothermal conditions. Sph. fuscum decomposes much more slowly than E. vaginatum. Low rate of transformation for Sph. fuscum is observed in drained and post-pyrogenic sites, while for E. vaginatum minimal rate of transformation is observed in the native site. During the decomposition of Sphagnum residues, 13C enrichment occurs, and during the decomposition of E. vaginatum, we observed 12C enrichment. The changes in the isotope composition of carbon for investigation sites are insignificant for Sphagnum fuscum, but it was observed for E. vaginatum, the largest of 13C depletion is observed in the drained site (−28.3‰) and minimal in the postpyrogenic site (−27.4‰).

Ecosystems in a State of Flux: Evidence from A Kenyan Coastal Riparian Ecosystem

Riparian ecosystems are considered hotspots of carbon and nitrogen transformations. These biochemical transformations are driven by anthropogenic activities in the immediate riverine water catchments. The anthropogenic activities may include and not limited to extraction of goods such as agricultural products, wood products, honey, plant based pharmaceutical products, livestock products, firewood, water and grass for thatching homesteads. Riparian ecosystems also provide important tangible and intangible ecosystem services comprising spiritual and aesthetic functions, pollination, ecosystem detoxification functions, carbon and nitrogen sequestration and CO2 sinks for amelioration of climate change impacts among others. These ecosystems are increasingly threatened by degradation attributed to land use changes. Human perturbations such as crop farming on riparian land, overgrazing and population pressure on land resources influence degradation of riparian ecosystems, with profound effects on biodiversity conservation and local livelihoods. Evidence from the literature indicates that although there is a general understanding regarding the response of terrestrial and wetland ecosystems to human perturbations, there is a dearth of information on the response of African riparian ecosystems to ecologic and socio-economic impacts.

Cross β Amyloid Nanotubes Demonstrate Promiscuous Catalysis in a Chemical Reaction Network via Co‐option

AbstractIn Darwin's warm pond rich with nutrients, lesser number of early catalytic machineries with modest capabilities were able to demonstrate promiscuity by catalyzing diverse biochemical transformations important for protometabolism. Herein, we report catalytically promiscuous amyloid‐based short peptide assemblies that could concomitantly catalyse three metabolically important yet orthogonal reactions. The surface exposed catalytic dyads featuring lysines and imidazoles were utilized for C=N condensation via dynamic covalent linkages and modulation of protonation events, respectively. Further, the peptide assemblies could promiscuously catalyse hydrolysis as well as retro‐aldol reactions, that could be co‐opted to facilitate C=N bond formation, either by a feedforward‐driven reaction network or by replenishing depleted substrates. The catalytic diversity of short peptide based promiscuous β‐sheet folds suggests their possible role in promoting the protometabolic network in early earth.

Cross β Amyloid Nanotubes Demonstrate Promiscuous Catalysis in a Chemical Reaction Network via Co-option.

In Darwin's warm pond rich with nutrients, lesser number of early catalytic machineries with modest capabilities were able to demonstrate promiscuity by catalyzing diverse biochemical transformations important for protometabolism. Herein, we report catalytically promiscuous amyloid-based short peptide assemblies that could concomitantly catalyse three metabolically important yet orthogonal reactions. The surface exposed catalytic dyads featuring lysines and imidazoles were utilized for C=N condensation via dynamic covalent linkages and modulation of protonation events, respectively. Further, the peptide assemblies could promiscuously catalyse hydrolysis as well as retro-aldol reactions, that could be co-opted to facilitate C=N bond formation, either by a feedforward-driven reaction network or by replenishing depleted substrates. The catalytic diversity of short peptide based promiscuous β-sheet folds suggests their possible role in promoting the protometabolic network in early earth.

Preparation of nano/microcapsules of ozonated olive oil in chitosan matrix and analysis of physicochemical and microbiological properties of the obtained films

In order to meet one of the greatest problems of food technology, i.e. unwanted food spoilage caused by the action of microorganisms, active or intelligent packaging is being created and used with increasing frequency. At the same time, substitutes for plastics are being sought in order to protect the environment. Biodegradable polymer composites seem to be an extremely promising material that could replace synthetic materials in the future. By encapsulating biologically active substances in a polymer matrix, directional action and controlled release of the substance are possible. The use of ozone, which has become more and more popular especially recently, allows to limit the growth of microorganisms, and the production of ozone derivatives of unsaturated fats allows to reduce the short time of its decomposition.The aim of this study was to analyse the physicochemical and bacteriostatic properties of innovative chitosan-based films containing encapsulated nanocapsules of ozonated olive oil in two concentrations. The morphology and size of the obtained nanocapsules were determined using Scanning Electron Microscopy and DLS. The largest particle size was observed for the film containing the lower ozone concentration – up to 4900 nm, in the control film 3500 nm, for the film with the highest ozone concentration, the particle size was the smallest, with the majority in the range of 100–1000 nm. Ozone content was determined by peroxidation number. The properties of the composites were characterised by infrared (IR) which proved that chitosan is a good matrix for the formation of capsules and ultraviolet (UV) which showed that the obtained composite absorbs light in the range of blue and near ultraviolet light, and the addition of nanocapsules of ozonated olive oil increased the degree of absorption and decreased the transparency. We also performed photoluminescence spectroscopy before and after storage of pork meat proving that films are sensitive to the physico-chemical and biochemical transformation products formed as a result of meat spoilage. The study of the microbiological properties included the analysis of the microbiological quality of pork meat stored under the obtained films as a function of time. The films have a bactericidal and bacteriostatic effect and the addition of ozonated olive oil capsules increases the bactericidal effect against Gram-negative bacteria. Contact angles, Water Vapour Transmission Rate and transparency were also determined and they were subjected to enzymatic hydrolysis. Water absorption, solubility and liquid absorption capacity were determined. All tested samples show high hydrophobicity and low solubility, and the ozone content directly influences these parameters.

(Invited) Practical Assessment of the Electrochemical Conversion of Methane to Methanol at Scale

Methane is the second-most emitted greenhouse gas (GHG) globally, and it has over 25x more potency toward the GHG effect than carbon dioxide. Methane emissions in the U.S. are equally distributed across the energy, agricultural, and industrial sectors – and occur in relatively small volumes at each site, though the total volume is sizable (e.g., 145 billion cubic meters of methane coextracted with U.S. oil alone per year). To avoid its direct emission, this “waste” methane is typically flared to produce CO2. Methane flaring sites contribute to approximately 2% of global CO2 emissions. These sites represent an opportunity to convert a waste stream into desirable products. Methane (natural gas)-to-chemicals conversion units are not implemented today because of economies of scale. Because each site is relatively small, the construction of a traditional stream-reforming based gas-to-liquid plant is not economically viable. It is also not profitable to build pipelines to these sites to take the natural gas to other locations.Recently, new concepts have been put forward for methanol production that are quoted as being more modular and possibly more profitable at smaller scales. Many of these concepts revolve around electrochemical and/or biochemical transformations. Proponents of electrochemical methane conversion have claimed that the technology will play a key role in eliminating these flare sites while opening up new business opportunities. Though this sounds very good, all of the research and development in this area remain on the bench scale as they have widely suffered from low current, high voltage losses and low faradaic efficiency. It should also be noted that there are very few studies in the literature that use economic analyses to understand the operational boundaries of a future electrochemical methane-to-methanol plant and to set realistic targets for its operation. Hence, research work is proceeding without clear operating targets in mind.In this presentation, we will present an economic analysis on an electrochemically driven methane-to-methanol plant. We investigate a wide range of possible production rates (from 2-2000 metric tons per day), operating current densities (10-1000 mA/cm2), operating voltages (Vthermo-2.0 V) and faradaic efficiencies. This analysis also takes into consideration the cost of the electrolyzer stacks, the balance-of-plant, building sizes/layouts, labor force, etc. Over this wide design space, we determine the possible operating space that will allow for profitable operation. While doing so, we test whether electrochemical processes can economically out-compete steam reforming plants at any scale. We also identify the operating modes where electrochemical processes emit fewer greenhouse gases that traditional plants.

The potential of proteomics in the study of processed meat products

Proteomics is a field that has grown rapidly since its emergence in the mid–1990s, reaching many disciplines such as food technology. The application of proteomic techniques in the study of complex biological samples such as foods, specifically meat products, allows scientists to decipher the underlying cellular mechanisms behind different quality traits. Lately, much emphasis has been placed on the discovery of biomarkers that facilitate the prediction of biochemical transformations of the product and provide key information on parameters associated with traceability and food safety. This review study focuses on the contribution of proteomics in the improvement of processed meat products. Different techniques and strategies have recently been successfully carried out in the study of the proteome of these products that can help the development of foods with a higher sensory quality, while ensuring consumer safety through early detection of microbiological contamination and fraud. SignificanceThe food industry and the academic world work together with the aim of responding to market demands, always seeking excellence. In particular, the meat industry has to face a series of challenges such as, achieving sensory attributes in accordance with the standards required by the consumer and maintaining a high level of safety and transparency, avoiding deliver adulterated and/or contaminated products. This review work exposes how the aforementioned challenges are attempted to be solved through proteomic technology, discussing the latest and most outstanding research in this regard, which undoubtedly contribute to improving the quality, in all the extension of the word, of meat products, providing relevant knowledge in the field of proteomic research.

MODIFICATION OF THE FATTY ACID PROFILE AS ADAPTATION OF BARLEY TO OXIDATIVE STRESS

The fatty acid profile of plants can respond to changes in environmental conditions. Oxidative stress, which develops as a result of water deficiency, is the leading abiotic stress in plant life. The mechanisms of adaptation to this factor are diverse and may include various physiological and biochemical transformations, for example, modification of the fatty acid profile. The aim of the work was to study the response at the level of barley fatty acids to water deficiency after electromagnetic treatment. For the first time, data on the regulation of the pool of fatty acids of spring barley (Hordeum vulgare L.) in conditions of water scarcity were obtained. The plants are grown from seeds treated in an ultra-high frequency electromagnetic field, with a lack of water in comparison with the conditions of normal humidification. The qualitative fatty acid profile of barley leaves does not change either under the influence of drought or under the influence of an electromagnetic field. However, the adaptation modification affects the quantitative composition – for example, under the influence of drought, the content of palmitic acid decreases by 2.03 times relative to the control. Pretreatment of barley seeds with an electromagnetic field and the development of barley in conditions of lack of moisture leads to a decrease in the content of such fatty acids as lauric, palmitoleic, oleic, petroselinic – the difference with the control is from 1.29 to 13.00 times. Under the same growth conditions, the content of pentadecanoic acid in chloroform leaf extract increases by an average of 1.42 times relative to non-irradiated plants with normal humidification conditions. The degree of unsaturation of the fatty acid profile of barley increases significantly under the consistent influence of an ultrahigh frequency electromagnetic field and water deficiency. Thus, electromagnetic treatment is able to partially compensate for the effects of oxidative stress on barley.

Microbial functional diversity across biogeochemical provinces in the central Pacific Ocean

Enzymes catalyze key reactions within Earth's life-sustaining biogeochemical cycles. Here, we use metaproteomics to examine the enzymatic capabilities of the microbial community (0.2 to 3 µm) along a 5,000-km-long, 1-km-deep transect in the central Pacific Ocean. Eighty-five percent of total protein abundance was of bacterial origin, with Archaea contributing 1.6%. Over 2,000 functional KEGG Ontology (KO) groups were identified, yet only 25 KO groups contributed over half of the protein abundance, simultaneously indicating abundant key functions and a long tail of diverse functions. Vertical attenuation of individual proteins displayed stratification of nutrient transport, carbon utilization, and environmental stress. The microbial community also varied along horizontal scales, shaped by environmental features specific to the oligotrophic North Pacific Subtropical Gyre, the oxygen-depleted Eastern Tropical North Pacific, and nutrient-rich equatorial upwelling. Some of the most abundant proteins were associated with nitrification and C1 metabolisms, with observed interactions between these pathways. The oxidoreductases nitrite oxidoreductase (NxrAB), nitrite reductase (NirK), ammonia monooxygenase (AmoABC), manganese oxidase (MnxG), formate dehydrogenase (FdoGH and FDH), and carbon monoxide dehydrogenase (CoxLM) displayed distributions indicative of biogeochemical status such as oxidative or nutritional stress, with the potential to be more sensitive than chemical sensors. Enzymes that mediate transformations of atmospheric gases like CO, CO2, NO, methanethiol, and methylamines were most abundant in the upwelling region. We identified hot spots of biochemical transformation in the central Pacific Ocean, highlighted previously understudied metabolic pathways in the environment, and provided rich empirical data for biogeochemical models critical for forecasting ecosystem response to climate change.

THE AMINO ACID COMPOSITION OF MEAT PRODUCTS TREATED WITH PREPARATIONS OF MICROBIAL ORIGIN

Fermentation in the technology of dry-cured meat products helps to create products with high sensory characteristics and an extended shelf life. The purpose of this work was to study how bacterial and enzyme preparations affected the accumulation of free amino acids in dry-cured meat products.
 The work considers how the preparation Iprovit-Lakmik based on the cultures L. plantarum, L. rhamnosus, L. casei, and Micrococcus varians acts on the accumulation of free amino acids during the ripening of dry-cured sausages, and how the bacterial preparation Iprovit-MKS based on the cultures Lactoba plantarum, L. rhamnosus, and Staphylococcus simulans and the enzyme preparation Protolad acts on proteolysis during the ripening of dry-cured whole-muscle products from pork and beef. Fermentation was carried out in a climatic chamber at a temperature required by the technological process of accelerated ripening of fermented sausages, using bacterial and enzyme preparations. The starter culture Iprovit-Lakmik was added in the amount 0.05% to the volume of the sausage mince prepared in accordance with the formulation of the dry-cured sausage Zhytomyrska. The preparations Protolad and Iprovit-MKS were added at the stage of injecting the balyk (cured fillet) Darnitsky. Samples with no preparations added were the controls. The amino acid composition of proteins was determined by ion-exchange chromatography on an automatic amino acid analyser Biotronik LC2000. The total content of free cyclic amino acids was determined by the Hull method, and that of acyclic amino acids by the Gomez method, using colourimetry.
 It has been found that after fermentation, each product had its own characteristics of the qualitative and quantitative accumulation of free amino acids. Adding the preparation Iprovit-Lakmik to raw meat allowed directed biochemical transformations with the formation of a significant amount of free amino acids, which exceeded the control by 115.86 mg/100 g of dry matter. The enzyme preparation Protolad has a positive effect on the chemical and physicochemical characteristics of salted products from pork and beef. It has been proved that its use activates the breakdown of muscle tissue proteins and increases the pool of free amino acids. In the test samples from pork and beef, the content of free amino acids increased, respectively, by 1.7 times and 3.4 times, and that of non-essential amino acids by 1.4 times and 1.3 times respectively, compared with the control. In the samples with the bacterial preparation Iprovit-MKS, the total amount of amino acids increased significantly: by 32% for beef balyk and by 20% for pork balyk.

Even allocation of benefits stabilizes microbial community engaged in metabolic division of labor.

Microbial communities execute metabolic pathways to drive global nutrient cycles. Within a community, functionally specialized strains can perform different yet complementary steps within a linear pathway, a phenomenon termed metabolic division of labor (MDOL). However, little is known about how such metabolic behaviors shape microbial communities. Here, we derive a theoretical framework to define the assembly of a community that degrades an organic compound through MDOL. The framework indicates that to ensure community stability, the strains performing the initial steps should hold a growth advantage (m) over the "private benefit" (n) of the strain performing the last step. The steady-state frequency of the last strain is then determined by the quotient of n and m. Our experiments show that the framework accurately predicts the assembly of our synthetic consortia that degrade naphthalene through MDOL. Our results provide insights for designing and managing stable microbial systems for metabolic pathway optimization.

Characteristics of ionization behaviors of aminonitrotoluene isomers produced by atmospheric pressure chemical ionization.

Six of the isomers of aminonitrotoluene (ANT) are 2-amino-3-nitrotoluene (2A3NT), 2A4NT, 2A5NT, 2A6NT, 4A2NT, and 4A3NT. Some of them can be identified by chromatography and spectroscopy. Biochemical transformation of 2,4,6-trinitrotoluene (TNT) and dinitrotoluenes (DNTs) is very complex and ANTs are decomposition products of TNT and DNTs. Each isomer in acetone was ionized using atmospheric pressure chemical ionization in positive and negative ion modes, and kinds and abundances of the product ions were analyzed. Energy-minimized structures of the product ions and their energies were calculated to explain the analysis results. The [M + H]+ , [M + H + Acetone - H2 O]+ , and [M + H + Acetone]+ ions as positive product ions were detected, while [M - H]- , M•- , and [M + O2 ]•- ions as negative ones were observed. The order of the ionization efficiencies for the positive product ions was 4A3NT > 4A2NT > 2A4NT > 2A6NT > 2A5NT > 2A3NT, while that of the negative ones was 2A5NT > 2A3NT > 4A3NT > 2A4NT > 2A6NT > 4A2NT. Ion abundance ratios for 2A3NT and 2A5NT showed very similar trends, while those of 2A6NT and 4A2NT also showed similar trends. Differences in the ionization behaviors were explained using the heats of reaction. The product ions were produced by ion-molecule reactions with the reactant ions of [2Acetone + H]+ and [Acetone + O2 ]•- . The [M + H + Acetone]+ ion was fragmented to produce [M + H]+ and [M + H + Acetone - H2 O]+ , while the [M + O2 ]•- ion was fragmented to generate the [M - H]- and M•- ions. Differences in the ionization behaviors of the ANTs can be used for their differentiation.

Native Protein Template Assisted Synthesis of Non-Native Metal-Sulfur Clusters

Metalloenzymes are the most proficient nature catalysts that are responsible for diverse biochemical transformations introducing excellent selectivity and performing at high rates, using intricate mutual relationships between metal ions and proteins. Inspired by nature, chemists started using naturally occurring proteins as templates to harbor non-native metal catalysts for the sustainable synthesis of molecules for pharmaceutical, biotechnological and industrial purposes. Therefore, metalloenzymes are the relevant targets for the design of artificial biocatalysts. The search and development of new scaffolds capable of hosting metals with high levels of selectivity could significantly expand the scope of bio-catalysis. To meet this challenge, herein, three native scaffolds: [1Fe-4Cys] (rubredoxin), [3Fe-4S] (ferredoxin), and [S2MoS2CuS2MoS2]-ORP (orange protein) protein scaffolds are case studies describing templates for the synthesis of non-native monomeric to mixed metal–sulfur clusters, which mimic native Ni containing metalloenzymes including [Ni-Fe] Hydrogenase and [Ni-Fe] CO Dehydrogenase. The non-native metal-substituted metalloproteins are not only useful for catalysis but also as spectroscopic probes.

Reversible Metal Ion/Complex Binding to Chitin Controlled by Ligand, Redox, and Photochemical Reactions and Active Movement of Chitin on Aquatic Arthropods

There is strong adsorption of metal ions and their complexes to chitin, which depends on both the oxidation and complexation states of many of the said elements (whereas others display chemical reactions detectable via electrochemical methods while being retained by chitin); thus, ad- and desorption at ambient water concentrations (often in the nMol/L range) are controlled by the presence and photochemical properties (concerning Eu and probably U and Ag) of mainly biogenic organic matter (both DOC and POC, and DON). With chitin forming the outer hull of mobile organisms (animals), this biopolymer is expected to take part in metal distribution in aquatic (limnetic and riverine) ecosystems. Having studied the attachment of many different elements to both crayfish and grafted (marine shrimp) chitin, with the highest accumulations observed in Bi, V, Ni, and LREEs, one should consider secondary biochemical transformations which take place at different water and sediment levels. After chitin had been embedded into sediment, methanogenesis (which requires Ni), Bi, and Sb biomethylations and photodesorption in the illuminated water column will occur if there are appropriate organics, causing the vertical separation of Eu from other REEs, at least during the daytime. Eutrophication will enhance both the production and especially the photooxidation rates of organics in water because phosphorylated sugars and lipids are formed quantitatively within min P, which enter water and undergo Eu-mediated photooxidation much more readily. Another biopolymer, gelatin, acts as an inert matrix-enhancing organic photooxidation product via Eu, producing chemical waves, indicating autocatalysis upon light impact. From the redox-related photodesorption of metal analytes from chitin, both sensors and devices for (light-assisted) electrochemical energy conversion are being developed by our workgroup. The electrochemical determination of adsorption thermodynamics on chitin is thus directly linked to its applications in environmental monitoring and technology.

Global protein dynamics as communication sensors in peptide synthetase domains.

Biological activity is governed by the timely redistribution of molecular interactions, and static structural snapshots often appear insufficient to provide the molecular determinants that choreograph communication. This conundrum applies to multidomain enzymatic systems called nonribosomal peptide synthetases (NRPSs), which assemble simple substrates into complex metabolites, where a dynamic domain organization challenges rational design to produce new pharmaceuticals. Using a nuclear magnetic resonance (NMR) atomic-level readout of biochemical transformations, we demonstrate that global structural fluctuations help promote substrate-dependent communication and allosteric responses, and impeding these global dynamics by a point-site mutation hampers allostery and molecular recognition. Our results establish global structural dynamics as sensors of molecular events that can remodel domain interactions, and they provide new perspectives on mechanisms of allostery, protein communication, and NRPS synthesis.