-
International Journal of Molecular... Feb 2024Turmeric, known for its curcuminoid-rich rhizome, particularly curcumin, exhibits notable antioxidant and antiviral properties. The likelihood of microbial contamination...
Turmeric, known for its curcuminoid-rich rhizome, particularly curcumin, exhibits notable antioxidant and antiviral properties. The likelihood of microbial contamination necessitates finding reliable techniques for subjecting the sample to radiation from this plant-based raw material. One alternative is to expose curcumin to radiation (e-beam), which was carried out as part of this research. Confirmation of the lack of curcumin decomposition was carried out using HPLC-DAD/MS techniques. Additionally, using the EPR technique, the generated free radicals were defined as radiation effects. Using a number of methods to assess the ability to scavenge free radicals (DPPH, ABTS, CUPRAC, and FRAP), a slight decrease in the activity of curcumin raw material was determined. The analysis of the characteristic bands in the FT-IR spectra allowed us to indicate changes in the phenolic OH groups as an effect of the presence of radicals formed.
Topics: Curcumin; Spectroscopy, Fourier Transform Infrared; Diarylheptanoids; Antioxidants; Free Radicals
PubMed: 38473770
DOI: 10.3390/ijms25052524 -
Molecules (Basel, Switzerland) Jun 2021Bee products are a well-known remedy against numerous diseases. However, from the consumers' perspective, it is essential to define factors that can affect their sensory...
Bee products are a well-known remedy against numerous diseases. However, from the consumers' perspective, it is essential to define factors that can affect their sensory acceptance. This investigation aimed to evaluate the volatile and sensory profiles, and sugar composition of beeswax, beebread, pollen, and honey. According to the HS-SPME/GC-MS results, 20 volatiles were identified in beeswax and honey, then 32 in beebread, and 33 in pollen. Alkanes were found to dominate in beeswax, beebread, and pollen, while aldehydes and monoterpenes in honey. In the case of sugars, a higher content of fructose was determined in beebread, bee pollen, and honey, whereas the highest content of glucose was assayed in beeswax. In the QDA, the highest aroma intensity characterized as honey-like and sweet was found in honey, while the acid aroma was typical of beebread. Other odor descriptors, including waxy, pungent, and plant-based aromas were noted only in beeswax, honey, and pollen, respectively.
Topics: Aldehydes; Alkanes; Animals; Bees; Gas Chromatography-Mass Spectrometry; Honey; Monoterpenes; Propolis; Sugars; Volatile Organic Compounds; Waxes
PubMed: 34199969
DOI: 10.3390/molecules26113410 -
Applied and Environmental Microbiology Nov 2017-Alkanes are ubiquitous in nature and are widely used by microorganisms as carbon sources. Alkane hydroxylation by alkane monooxygenases is a critical step in the...
-Alkanes are ubiquitous in nature and are widely used by microorganisms as carbon sources. Alkane hydroxylation by alkane monooxygenases is a critical step in the aerobic biodegradation of -alkanes, which plays important roles in natural alkane attenuation and is used in industrial and environmental applications. The alkane oxidation operon, , in the alkane-degrading strain sp. strain DQ12-45-1b is negatively autoregulated by the TetR family repressor AlkX via a product positive feedback mechanism. To predict the gene regulation mechanism, we determined the 3.1-Å crystal structure of an AlkX homodimer in a non-DNA-bound state. The structure showed traceable long electron density deep inside a hydrophobic cavity of each monomer along the long axis of the helix bundle, and further gas chromatography-mass spectrometry analysis of AlkX revealed that it contained the -derived long-chain fatty acid molecules as a ligand. Moreover, an unusual structural feature of AlkX is an extra helix, α6', forming a lid-like structure with α6 covering the inducer-binding pocket and occupying the space between the two symmetrical DNA-binding motifs in one dimer, indicating a distinct conformational transition mode in modulating DNA binding. Sequence alignment of AlkX homologs from strains showed that the residues involved in DNA and inducer binding are highly conserved, suggesting that the regulation mechanisms of -alkane hydroxylation are possibly a common characteristic of strains. With -alkanes being ubiquitous in nature, many bacteria from terrestrial and aquatic environments have evolved -alkane oxidation functions. Alkane hydroxylation by alkane monooxygenases is a critical step in the aerobic biodegradation of -alkanes, which plays important roles in natural alkane attenuation and petroleum-contaminating environment bioremediation. The gene regulation of the most common alkane hydroxylase, AlkB, has been studied widely in Gram-negative bacteria but has been less explored in Gram-positive bacteria. Our previous study showed that the TetR family regulator (TFR) AlkX negatively autoregulated the alkane oxidation operon, , in the Gram-positive strain sp. strain DQ12-45-1b. Although TFRs are one of the most common transcriptional regulator families in bacteria, the TFR involved in -alkane metabolism has been reported only recently. In this study, we determined the crystal structure of AlkX, which implies a distinct DNA/ligand binding mode. Our results shed light upon the regulation mechanism of the common alkane degradation process in nature.
Topics: Actinomycetales; Alkanes; Amino Acid Motifs; Bacterial Proteins; Biodegradation, Environmental; Gene Expression Regulation, Bacterial; Repressor Proteins
PubMed: 28821550
DOI: 10.1128/AEM.01447-17 -
Ecotoxicology and Environmental Safety Aug 2022In the process of marine oil spill remediation, adding highly efficient oil degrading microorganisms can effectively promote oil degradation. However, in practice, the...
In the process of marine oil spill remediation, adding highly efficient oil degrading microorganisms can effectively promote oil degradation. However, in practice, the effect is far less than expected due to the inadaptability of microorganisms to the environment and their disadvantage in the competition with indigenous bacteria for nutrients. In this article, four strains of oil degrading bacteria were isolated from seawater in Jiaozhou Bay, China, where a crude oil pipeline explosion occurred seven years ago. Results of high-throughput sequencing, diesel degradation tests and surface activity tests indicated that Peseudomonas aeruginosa ZS1 was a highly efficient petroleum degrading bacterium with the ability to produce surface active substances. A diesel oil-degrading bacterial consortium (named SA) was constructed by ZS1 and another oil degrading bacteria by diesel degradation test. Degradation products analysis indicated that SA has a good ability to degrade short chain alkanes, especially n-alkanes (C-C). Community structure analysis showed that OTUs of Alcanivorax, Peseudomona, Ruegeria, Pseudophaeobacter, Hyphomonas and Thalassospira on genus level increased after the oil spill and remained stable throughout the recovery period. Most of these enriched microorganisms were related to known alkane and hydrocarbon degraders by the previous study. However, it is the first time to report that Pseudophaeobacter was enriched by using diesel as the sole carbon source. The results also indicated that ZS1 may have a dominant position in competition with indigenous bacteria. Oil pollution has an obvious selective effect on marine microorganisms. Although the oil degradation was promoted after SA injection, the recovery of microbial community structure took a longer time.
Topics: Alkanes; Bacteria; Biodegradation, Environmental; Hydrocarbons; Petroleum; Petroleum Pollution; Seawater
PubMed: 35738097
DOI: 10.1016/j.ecoenv.2022.113769 -
Biotechnology and Bioengineering Nov 2022Microorganisms build fatty acids with biocatalytic assembly lines, or fatty acid synthases (FASs), that can be repurposed to produce a broad set of fuels and chemicals....
Microorganisms build fatty acids with biocatalytic assembly lines, or fatty acid synthases (FASs), that can be repurposed to produce a broad set of fuels and chemicals. Despite their versatility, the product profiles of FAS-based pathways are challenging to adjust without experimental iteration, and off-target products are common. This study uses a detailed kinetic model of the Escherichia coli FAS as a foundation to model nine oleochemical pathways. These models provide good fits to experimental data and help explain unexpected results from in vivo studies. An analysis of pathways for alkanes and fatty acid ethyl esters (FAEEs), for example, suggests that reductions in titer caused by enzyme overexpression-an experimentally consistent phenomenon-can result from shifts in metabolite pools that are incompatible with the substrate specificities of downstream enzymes, and a focused examination of multiple alcohol pathways indicates that coordinated shifts in enzyme concentrations provide a general means of tuning the product profiles of pathways with promiscuous components. The study concludes by integrating all models into a graphical user interface. The models supplied by this work provide a versatile kinetic framework for studying oleochemical pathways in different biochemical contexts.
Topics: Alkanes; Escherichia coli; Fatty Acid Synthases; Fatty Acids; Metabolic Engineering
PubMed: 35959746
DOI: 10.1002/bit.28209 -
Plant Physiology Feb 2019Plant aerial organs are coated with cuticular waxes, a hydrophobic layer that primarily serves as a waterproofing barrier. Cuticular wax is a mixture of aliphatic...
Plant aerial organs are coated with cuticular waxes, a hydrophobic layer that primarily serves as a waterproofing barrier. Cuticular wax is a mixture of aliphatic very-long-chain molecules, ranging from 22 to 48 carbons, produced in the endoplasmic reticulum of epidermal cells. Among all wax components, alkanes represent up to 80% of total wax in Arabidopsis () leaves. Odd-numbered alkanes and their derivatives are produced through the alkane-forming pathway. Although the chemical reactions of this pathway have been well described, the enzymatic mechanisms catalyzing these reactions remain unclear. We previously showed that a complex made of Arabidopsis ECERIFERUM1 (CER1) and CER3 catalyzes the conversion of acyl-Coenzyme A's to alkanes with strict substrate specificity for compounds containing more than 29 carbons. To learn more about alkane biosynthesis in Arabidopsis, we characterized the biochemical specificity and physiological functions of a CER1 homolog, CER1-LIKE1. In a yeast strain engineered to produce very-long-chain fatty acids, CER1-LIKE1 interacted with CER3 and cytochrome B5 to form a functional complex leading to the production of alkanes that are of different chain lengths compared to that produced by CER1-containing complexes. Gene expression analysis showed that both and are differentially expressed in an organ- and tissue-specific manner. Moreover, the inactivation or overexpression of in Arabidopsis transgenic lines specifically impacted alkane biosynthesis and wax crystallization. Collectively, our study reports on the identification of a further plant alkane synthesis enzymatic component and supports a model in which several alkane-forming complexes with distinct chain-length specificities coexist in plants.
Topics: Alkanes; Arabidopsis; Arabidopsis Proteins; Carbon-Carbon Lyases; Gene Expression Regulation, Plant; Mutation; Nuclear Proteins; Plant Leaves; Plant Stems; Plants, Genetically Modified; Saccharomyces cerevisiae; Nicotiana; Waxes
PubMed: 30514726
DOI: 10.1104/pp.18.01075 -
Applied and Environmental Microbiology Aug 2019Methanogenic degradation of -alkanes is prevalent in -alkane-impacted anoxic oil reservoirs and oil-polluted sites. However, little is known about the initial activation...
Methanogenic degradation of -alkanes is prevalent in -alkane-impacted anoxic oil reservoirs and oil-polluted sites. However, little is known about the initial activation mechanism of the substrate, especially -alkanes with a chain length above C Here, a methanogenic C to C-alkane-degrading enrichment culture was established from production water of a low-temperature oil reservoir. At the end of the incubation (364 days), C to C (1-methylalkyl)succinates were detected in the -alkane-amended enrichment culture, suggesting that fumarate addition had occurred in the degradation process. This evidence is supported further by the positive amplification of the gene encoding the alpha subunit of alkylsuccinate synthase. A phylogenetic analysis shows these amplicons to be affiliated with and clades. Together with the high abundance of these clades in the bacterial community, these two species are postulated to be the key players in the degradation of C to C-alkanes in the present study. Our results provide evidence that long -alkanes are activated via a fumarate addition mechanism under methanogenic conditions. Methanogenic hydrocarbon degradation is the major process for oil degradation in subsurface oil reservoirs and is blamed for the formation of heavy oil and oil sands. Addition of -alkanes to fumarate yielding alkyl-substituted succinates is a well-characterized anaerobic activation mechanism for hydrocarbons and is the most common activation mechanism in the anaerobic biodegradation of -alkanes with chain lengths less than C However, the activation mechanism involved in the methanogenic biodegradation of -alkanes longer than C is still uncertain. In this study, we analyzed a methanogenic enrichment culture amended with a mixture of C to C-alkanes. These -alkanes can be activated via fumarate addition by mixed cultures containing and species under methanogenic conditions. These observations provide a fundamental understanding of long--alkane metabolism under methanogenic conditions and have important applications for the remediation of oil-contaminated sites and for energy recovery from oil reservoirs.
Topics: Alkanes; Archaea; Bacterial Proteins; Biodegradation, Environmental; Chemoautotrophic Growth; Deltaproteobacteria; Fumarates; Methane; Phylogeny
PubMed: 31175186
DOI: 10.1128/AEM.00985-19 -
Journal of the American Chemical Society Oct 2017The catalytic transformation of a C(sp)-H bond to a C(sp)-C bond via an iron carbene intermediate represents a long-standing challenge. Despite the success of enzymatic...
The catalytic transformation of a C(sp)-H bond to a C(sp)-C bond via an iron carbene intermediate represents a long-standing challenge. Despite the success of enzymatic and small molecule iron catalysts mediating challenging C(sp)-H oxidations and aminations via high-valent iron oxos and nitrenes, C(sp)-H alkylations via isoelectronic iron carbene intermediates have thus far been unsuccessful. Iron carbenes have been inert, or shown to favor olefin cyclopropanation and heteroatom-hydrogen insertion. Herein we report an iron phthalocyanine-catalyzed alkylation of allylic and benzylic C(sp)-H bonds. Mechanistic investigations support that an electrophilic iron carbene mediates homolytic C-H cleavage and rebounds from the resulting organoiron intermediate to form the C-C bond; both steps are tunable via catalyst modifications. These studies suggest that for iron carbenes, distinct from other late metal carbenes, C-H cleavage is partially rate-determining and must be promoted to effect reactivity.
Topics: Alkylation; Catalysis; Iron; Methane; Molecular Structure; Stereoisomerism
PubMed: 28898063
DOI: 10.1021/jacs.7b07602 -
Nature Structural & Molecular Biology Apr 2023Alkane monooxygenase (AlkB) is a widely occurring integral membrane metalloenzyme that catalyzes the initial step in the functionalization of recalcitrant alkanes with...
Alkane monooxygenase (AlkB) is a widely occurring integral membrane metalloenzyme that catalyzes the initial step in the functionalization of recalcitrant alkanes with high terminal selectivity. AlkB enables diverse microorganisms to use alkanes as their sole carbon and energy source. Here we present the 48.6-kDa cryo-electron microscopy structure of a natural fusion from Fontimonas thermophila between AlkB and its electron donor AlkG at 2.76 Å resolution. The AlkB portion contains six transmembrane helices with an alkane entry tunnel within its transmembrane domain. A dodecane substrate is oriented by hydrophobic tunnel-lining residues to present a terminal C-H bond toward a diiron active site. AlkG, an [Fe-4S] rubredoxin, docks via electrostatic interactions and sequentially transfers electrons to the diiron center. The archetypal structural complex presented reveals the basis for terminal C-H selectivity and functionalization within this broadly distributed evolutionary class of enzymes.
Topics: Cryoelectron Microscopy; Cytochrome P-450 CYP4A; Alkanes
PubMed: 36997762
DOI: 10.1038/s41594-023-00958-0 -
Proceedings of the National Academy of... Sep 2022Mercaptoethane sulfonate or coenzyme M (CoM) is the smallest known organic cofactor and is most commonly associated with the methane-forming step in all methanogenic...
Mercaptoethane sulfonate or coenzyme M (CoM) is the smallest known organic cofactor and is most commonly associated with the methane-forming step in all methanogenic archaea but is also associated with the anaerobic oxidation of methane to CO in anaerobic methanotrophic archaea and the oxidation of short-chain alkanes in species. It has also been found in a small number of bacteria capable of the metabolism of small organics. Although many of the steps for CoM biosynthesis in methanogenic archaea have been elucidated, a complete pathway for the biosynthesis of CoM in archaea or bacteria has not been reported. Here, we present the complete CoM biosynthesis pathway in bacteria, revealing distinct chemical steps relative to CoM biosynthesis in methanogenic archaea. The existence of different pathways represents a profound instance of convergent evolution. The five-step pathway involves the addition of sulfite, the elimination of phosphate, decarboxylation, thiolation, and the reduction to affect the sequential conversion of phosphoenolpyruvate to CoM. The salient features of the pathway demonstrate reactivities for members of large aspartase/fumarase and pyridoxal 5'-phosphate-dependent enzyme families.
Topics: Anaerobiosis; Archaea; Bacteria; Coenzymes; Euryarchaeota; Mesna; Methane; Oxidation-Reduction; Phosphates
PubMed: 36037354
DOI: 10.1073/pnas.2207190119