Sequential Degradation Research Articles

Sequential conversion of lignite in alkaline water by oxidative degradation, dissolution and catalytic gasification

We have demonstrated a sequence of degradation, dissolution and catalytic hydrothermal gasification (CHTG) of lignite in alkaline water. A Victorian lignite was subjected to hydrothermal treatment (HT) in an aqueous solution of NaOH at 250 °C, and then oxidation with pressurized O2 at 100 °C. The sequential HT and oxidation solubilized a 95% portion of the lignite on mass/carbon bases. The resulting solution was further converted by CHTG in a flow reactor at 350 °C for 10 h, employing a ruthenium/activated-charcoal catalyst (ruthenium loading; 16 wt%). The initial carbon conversion to gas was as high as 98% while CH4, CO2 and H2 were produced. The conversion gradually decreased due to coke deposition over the catalyst but was near steady around 83% at 8–10 h. The solubilized lignite consisted of compounds with molecular mass up to 5,000. The heavier portion (molecular mass > 1,000) was responsible for the coke formation and accumulation that caused the catalyst deactivation.

Methane Production in Soil Environments-Anaerobic Biogeochemistry and Microbial Life between Flooding and Desiccation.

Flooding and desiccation of soil environments mainly affect the availability of water and oxygen. While water is necessary for all life, oxygen is required for aerobic microorganisms. In the absence of O2, anaerobic processes such as CH4 production prevail. There is a substantial theoretical knowledge of the biogeochemistry and microbiology of processes in the absence of O2. Noteworthy are processes involved in the sequential degradation of organic matter coupled with the sequential reduction of electron acceptors, and, finally, the formation of CH4. These processes follow basic thermodynamic and kinetic principles, but also require the presence of microorganisms as catalysts. Meanwhile, there is a lot of empirical data that combines the observation of process function with the structure of microbial communities. While most of these observations confirmed existing theoretical knowledge, some resulted in new information. One important example was the observation that methanogens, which have been believed to be strictly anaerobic, can tolerate O2 to quite some extent and thus survive desiccation of flooded soil environments amazingly well. Another example is the strong indication of the importance of redox-active soil organic carbon compounds, which may affect the rates and pathways of CH4 production. It is noteworthy that drainage and aeration turns flooded soils, not generally, into sinks for atmospheric CH4, probably due to the peculiarities of the resident methanotrophic bacteria.

Mechanism and Kinetic Study on the Degradation of Typical Biomass Tar Components (Toluene, Phenol and Naphthalene) by Ozone

ABSTRACT The detailed reaction mechanisms for degrading typical biomass tar components (toluene, phenol and naphthalene) by ozone were investigated by employing Density Functional Theory and ab-initio methods. Results showed that toluene, phenol and naphthalene were degraded by ozone in a similar way by destroying C=C bonds and aromatic ring. For toluene and phenol, ozone preferentially destroys C=C bonds at the 1,2-position because of the activation of methyl and hydroxy groups. Relatively, for naphthalene, ozone preferentially destroys C=C bonds at the 2,3-position because of the activation of the middle sharing C=C bond. Based on the mechanism study, the kinetic parameters of the reactions were also calculated by Transition State Theory. The calculated rate constant for degrading toluene by ozone was in good agreement with the literature experimental result. The theoretical calculation was reasonable and reliable. The rate constant for degrading naphthalene by ozone was larger than that for degrading phenol, and the rate constants for degrading phenol by ozone were larger than that for degrading toluene. The degradation sequence of typical biomass tar components by ozone was that naphthalene > phenol > toluene.

Degradation of Homestead Hollow at the InSight Landing Site Based on the Distribution and Properties of Local Deposits

AbstractThe InSight mission landed its scientific payload in Homestead hollow, a quasi‐circular depression interpreted to be a highly degraded impact crater that is 27 m in diameter. The original pristine crater formed in a preexisting impact‐generated regolith averaging ~3 m thick and the surrounding ejecta deposit, consisting of coarse and mostly fine fragments, was in disequilibrium with local geomorphic thresholds. As a result, early, relatively rapid degradation by mostly eolian, and lesser impact processes and mass‐wasting, stripped the rim and mostly infilled the hollow where sediments were sequestered. Early, faster degradation during the first ~0.1 Ga was followed by much slower degradation over the bulk of the 0.4–0.7 Ga history of the crater. Pulses of much lesser degradation are attributed to impacts in and nearby the hollow, which emplaced some rocks as ejecta and provided small inventories of fine sediments for limited additional infilling. Even lesser sediments were derived from the very slow production of fines via weathering of resistant basaltic rocks. Nevertheless, indurated regolith caps the sediment fill within the hollow and creates a relatively stable present‐day surface that further sequesters infilling sediments from remobilization. The degradation sequence at Homestead hollow is like that established at the Spirit rover landing site in Gusev crater and points to the importance of eolian, and lesser impact and mass‐wasting processes, in degrading volcanic surfaces on Mars over the past ~1 Ga.

Fabrication of a double-layer membrane cathode based on modified carbon nanotubes for the sequential electro-Fenton oxidation of p-nitrophenol

To improve the electrocatalytic efficiency of the cathode and provide a wider pH range in the electro-Fenton process, N-doped multi-walled carbon nanotubes (NCNTs) and ferrous ion complexed with carboxylated carbon nanotubes (CNT-COOFe2+) were used to fabricate the diffusion layer and catalyst layer of a membrane cathode, respectively. The morphology, structure, and composition of CNT-COOFe2+ were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). The oxygen reduction performance of NCNT was evaluated using cyclic voltammetry (CV) and the rotating disk electrode technique (RDE). In addition, a potential application of the cathode in sequential electro-Fenton degradation of p-nitrophenol (p-NP) was investigated. The results revealed that iron was successfully doped on the carboxylated carbon nanotubes in ionic complexation form and the content of iron atoms in CNT-COOFe2+ was 2.65%. Furthermore, the defects on the tube walls provided more reactive sites for the electro-Fenton process. A combination of CV and RDE data indicated that NCNT had better electrocatalytic H2O2 generation activity with a more positive onset potential and higher cathodic peak current response than CNT. A p-NP removal rate of 96.04% was achieved within 120min, and a mineralization efficiency of 80.26% was obtained at 180min in the sequential electro-Fenton process at a cathodic potential of - 0.7V vs SCE and neutral pH. The activity of the used cathode was restored simply through electro-reduction at - 1.0V vs SCE, and a p-NP removal rate of more than 70% was obtained at 60min after six regeneration cycles.

Mechanisms regulating PIF transcription factor activity at the protein level.

Plant growth and development are precisely regulated by transcription factors (TFs) such as the PHYTOCHROME INTERACTING FACTORs (PIFs). PIFs regulate growth in response to various internal and external stimuli, and, accordingly, are regulated by a variety of different factors and mechanisms. Canonically, PIF activity is inhibited by light through the sequential phosphorylation, ubiquitination and degradation of these TFs in a manner dependent on their interaction with active phytochrome photoreceptors. However, work in more recent years has revealed that phytochromes also antagonize PIF activity by inhibiting their ability to bind DNA and, at least in the case of PIF7, by causing it to be retained in the cytoplasm. Recent work has also revealed specific kinases, phosphatases and E3 ubiquitin ligases which alter PIFs at the post-translational level. In a few cases, these studies have gone as far as identifying potential kinases responsible for phosphorylating PIFs in response to light. Moreover, additional factors have been identified that positively or negatively affect PIF binding to DNA or bind directly to PIF-DNA complexes and affect the transcriptional activation of target genes by these TFs. This review summarizes the variety of different mechanisms involved in PIF regulation and discusses some of the major unanswered questions in this area of research.

Identification of drought resistant miRNA in Macleaya cordata by high-throughput sequencing

Drought is one of the most serious factors affecting crop yields in the world. Macleaya cordata (Willd.) is a draught-tolerant medicinal plant that has been proposed as a pioneer crop to be cultivated in arid areas. However, the exact molecular mechanisms through which M. cordata responds to draught stress remain elusive. In recent years, microRNA (miRNAs) in plants have been associated with stress response. Based on these findings, the current study aimed to shed light on the potential regulatory roles of miRNAs in the draught tolerance of M. cordata by employing high-throughput RNA sequencing and degradation sequencing. Six M. cordata plants were randomly divided into two equal experiment groups, including one draught group and one control group. High-throughput sequencing of the M. cordata samples led to the identification of 895 miRNAs, of which 18 showed significantly different expression levels between the two groups. PsRobot analysis and degradation sequencing predicted the differential miRNAs to target 59 and 36 genes, respectively. Functional analysis showed that 38 of the predicted genes could be implicated in the modulation of stress response. Four miRNAs and eight target genes were selected for quantitative real-time polymerase chain reaction (qRT-PCR) validation. The expression trend of each miRNA analyzed by qRT-PCR was consistent with that determined by sequencing, and was negatively correlated with those of its target genes. The results of our current study supported the involvement of miRNAs in the draught tolerance of M. cordata and could pave the way for further investigation into the related regulatory mechanisms.

Thiol-Methylsulfone-Based Hydrogels for 3D Cell Encapsulation.

Thiol-maleimide and thiol-vinylsulfone cross-linked hydrogels are widely used systems in 3D culture models, in spite of presenting uncomfortable reaction kinetics for cell encapsulation: too fast (seconds for thiol-maleimide) or too slow (minutes-hours for thiol-vinylsulfone). Here, we introduce the thiol-methylsulfone reaction as alternative cross-linking chemistry for cell encapsulation, particularized for PEG-hydrogels. The thiol-methylsulfone reaction occurs at high conversion and at intermediate reaction speed (seconds-minutes) under physiological pH range. These properties allow easy mixing of hydrogel precursors and cells to render homogeneous cell-laden gels at comfortable experimental time scales. The resulting hydrogels are cytocompatible and show comparable hydrolytic stability to thiol-vinylsulfone gels. They allow direct bioconjugation of thiol-derivatized ligands and tunable degradation kinetics by cross-linking with degradable peptide sequences. 3D cell culture of two cell types, fibroblasts and human umbilical vein endothelial cells (HUVECs), is demonstrated.

Strategies to investigate protein turnover with fluorescent protein reporters in eukaryotic organisms

In higher eukaryotes, defects in regulated protein turnover are intimately linked to development of diseases and aging. Systematic investigation of proteostasis and protein degradation pathways is of high importance for understanding basic cellular events as well as developmental processes in higher organisms. Recently, novel fluorescent protein-based tools for monitoring protein degradation and mapping degradation pathways were described that facilitate this task. Here we give an overview of these tools and relate them to biophysical properties of fluorescent proteins. We focus on methods for the identification of degradation pathways, the discovery of novel degradation sequences, the investigation of proteome dynamics, and the characterization of protein stability. One can expect systematic application of these tools in the near future by systems biology approaches enhancing understanding of the ubiquitin-proteasome system from single protein degradation pathways to its influence on developmental processes.

A green approach to synthesis of ZnO nanoparticles using jujube fruit extract and their application in photocatalytic degradation of organic dyes

Zinc oxide nanoparticles (NPs) were synthesized using a green method in the presence of jujube fruit extract as a reducing agent and a stabilizer. The characteristics of the NPs were determined by various analyses, including transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier-transform infrared (FTIR), scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDX). The results suggest that high quality ZnO NPs in terms of size distribution and morphology were synthesized. The obtained NPs were then used as photocatalyst to degrade two organic dyes, methylene blue (MB) and eriochrome black-T (ECBT) in a model wastewater under direct sunlight. The kinetics of photodegradation of the aforesaid organic dyes was also studied. ZnO NPs exhibited a great photocatalytic performance, which resulted in degradation efficiencies of about 92% and 86% within 5h at the rate constants of 8.7×10-3min-1 and 6.7×10-3min-1 for MB and ECBT, respectively. Moreover, the NPs demonstrated stable photocatalytic activity after sequential degradation experiments.

Sequential degradation of raw vinasse by a laccase enzyme producing fungus Pleurotus sajor-caju and its ATPS purification

This study evaluated simultaneously the raw vinasse degradation, an effluent from the sugar-alcohol industry, the laccase production by Pleurotus sajor-caju and its purification using aqueous two-phase systems (ATPS). To improve laccase production, different concentrations of inducers (ethanol and CuSO4) were added. The higher laccase production promoted an increase of 4-fold using 0.4 mM of CuSO4 as inducer, with maximum enzymatic activity of 539.3 U/L on the 3rd day of fermentation. The final treated vinasse had a decolorization of 92% and turbidity removal of 99% using CuSO4. Moreover, the produced laccase was then purified by ATPS in a single purification step, reaching 2.9-fold and recovered ≈ 99,9 %, in the top phase (PEG-rich phase) using 12 wt% of PEG 1500 + 20 wt% of citrate buffer + enzyme broth + water, at 25 °C. Thus, an integrated process of vinasse degradation, laccase production and purification with potential industrial application was proposed.

Molarity provides better clarity – using molar-based data when evaluating chlorinated volatile organic compound impacted sites

Chlorinated volatile organic compounds are common constituents observed at many contaminated groundwater sites. Common industry practice has been to measure these constituents in groundwater on a weight concentration basis (e.g. µg/l, mg/l). This paper highlights the use of molar-based concentrations, especially in the case of parent-daughter degradation sequences commonly observed with the chloroethene, chloroethane, and chloromethane families of compounds. Converting to molar-based concentrations provides the practitioner greater insight into groundwater plume behavior including better evaluation of degradation processes, remedial progress, possible commingling, and/or sourcing. For example, this paper provides a tank analogy to evaluate whether the commonly misinterpreted observation of “DCE-stall” may be occurring at a site. Multiple examples of the benefits of using molar-based concentration data are also summarized in a project case study presented herein. As demonstrated in this paper, molarity does provide better clarity and can be a powerful evaluation tool in the groundwater practitioner’s toolbox.

Monitoring the changes in low molecular weight carbohydrates in cocoa beans during spontaneous fermentation: A chemometric and kinetic approach.

The low molecular weight carbohydrate (LMWC) profile has recently been investigated, showing considerable changes between fermented and unfermented cocoa beans. These differences are a consequence of the fermentation process, which is considered a crucial step in chocolate production. During fermentation, LMWC are involved in Maillard reaction, a crucial reaction for the development of aroma and taste precursors. However, there is a lack of information related to LMWC changes and of contextualization with changes in other physicochemical parameters (pH and dry matter) during spontaneous fermentation. The different approaches employed in this manuscript have allowed the identification of a sequential degradation of tetra-, tri- and disaccharides, as well as an increase in the monosaccharide content during fermentation. Moreover, a correlation was determined between some LMWC and physicochemical parameters. Besides that, the chemometric approach identified the fermentation period ranging between 48 and 96h as determinant to produce noticeable changes in unfermented beans based on the indicators evaluated. Furthermore, different kinetic parameteres (reaction order, observed reaction rates (kobs) and half-life values (t1/2)) of different LMWC were determined, showing differences between them. The results showed in this manuscript provide unprecedented mechanistic details of spontaneous cocoa fermentation.

A novel TiO2/graphite felt photoanode assisted electro-Fenton catalytic membrane process for sequential degradation of antibiotic florfenicol and elimination of its antibacterial activity

Abstract Antibiotics, especially halogenated antibiotics, which account for nearly 40% of the total antibiotics in China, pose great environmental risks; however, the superior stability of C–F bond and low concentrations hinder their degradation, indicating the need for developing of highly efficient treatment technologies. There is an additional concern that some degradation products could be as active/toxic as or even more than their parent compound. The stable C–F bond can be relative easily cleaved by UV light irradiation, which could come from sunlight. Herein, a novel UV-driven electro-Fenton catalytic membrane (UV-EFCM) filtration system that favors resistance elimination and efficient degradation of low-concentration antibiotics is proposed for the first time. The photo-electrochemical/electro-Fenton (PEC/EF) coupling reaction is synchronously conducted in a sequential filtration system. Almost complete degradation and high mineralization (78.4 ± 9.1%) of florfenicol were achieved at a concentration of as low as 14 µM with the hydraulic retention time of 0.98 h during the UV-EFCM filtration system. Complete elimination of its antibacterial activity, and significant defluorination improvement (56 ± 3.6%) compared to electro-Fenton filtration process (11 ± 5.3%) were achieved due to the prior cleavage of the stable C–F bond with antibiotic potency under UV light pretreatment. This study thus proposes a novel UV-EFCM filtration system, which couples PEC and EF with a potential to tackle the environmental problems associated with antibiotic pollution.

Optimal degradation-based burn-in policy using Tweedie exponential-dispersion process model with measurement errors

In this paper, degradation-based burn-in for highly-reliable products subject to degradation is studied. Since the common degradation models for burn-in are usually established on the basis of a specific stochastic process, such as Wiener process and gamma process, it greatly restricts the scope of application. Moreover, measurement errors are often inevitable due to the imperfect inspection and environment disturbance. Hence, a Tweedie exponential-dispersion process with measurement errors (TEDPE) model is developed to describe the degradation paths of the population which includes weak units and normal units. The TEDPE model contains the common stochastic process models as special case by setting different forms of variance function. Then, a joint saddle-point approximation and expectation maximization algorithm is proposed for parameter estimation. To identity and eliminate weak units, the linear discriminant analysis method, which can make full use of the degradation sequence of observations, is used to develop classification criterion. The optimal burn-in policy involving the duration and cutoff point can be obtained by minimizing the total per-unit cost. Furthermore, considering the failure costs in field operation, a joint policy of burn-in and preventive maintenance is optimized. Finally, a case study based on an IRLED dataset is implemented to illustrate the proposed methods.

Modelling hydrolysis: Simultaneous versus sequential biodegradation of the hydrolysable fractions

Hydrolysis is considered the limiting step during solid waste anaerobic digestion (including co-digestion of sludge and biosolids). Mechanisms of hydrolysis are mechanistically not well understood with detrimental impact on model predictive capability. The common approach to multiple substrates is to consider simultaneous degradation of the substrates. This may not have the capacity to separate the different kinetics. Sequential degradation of substrates is theoretically supported by microbial capacity and the composite nature of substrates (bioaccessibility concept). However, this has not been experimentally assessed. Sequential chemical fractionation has been successfully used to define inputs for an anaerobic digestion model. In this paper, sequential extractions of organic substrates were evaluated in order to compare both models. By removing each fraction (from the most accessible to the least accessible fraction) from three different substrates, anaerobic incubation tests showed that for physically structured substrates, such as activated sludge and wheat straw, sequential approach could better describe experimental results, while this was less important for homogeneous materials such as pulped fruit. Following this, anaerobic incubation tests were performed on five substrates. Cumulative methane production was modelled by the simultaneous and sequential approaches. Results showed that the sequential model could fit the experimental data for all the substrates whereas simultaneous model did not work for some substrates.

A modular PROTAC design for target destruction using a degradation signal based on a single amino acid

Proteolysis targeting chimeras (PROTACs) are bivalent molecules that bring a cellular protein to a ubiquitin ligase E3 for ubiquitination and subsequent degradation. Although PROTAC has emerged as a promising therapeutic means for cancers as it rewires the ubiquitin pathway to destroy key cancer regulators, the degradation signals/pathways for PROTACs remain underdeveloped. Here we append single amino acids, the simplest degradation signal, to a ligand specific for estrogen-related receptor α (ERRα) and demonstrate their utility in ERRα knockdown via the N-end rule pathway and also their efficiency in the growth inhibition of breast cancer cells. The modular design described offers unique advantages including smaller molecular size with shortest degradation sequences and degradation speed modulation with different amino acids. Our study expands the repertoire of limited ubiquitin pathways currently available for PROTACs and could be easily adapted for broad use in targeted protein degradation.

Sequential microbial-photocatalytic degradation of imidacloprid

In the present study, the application of sequential biological and photocatalytic process was evaluated as a feasible process for the degradation of imidacloprid (IMI) in soil. Photocatalysis was carried out as a post and pre-treatment to the biological process as Microbial Photocatalytic (MP) and Photocatalytic Microbial (PM), respectively, to enhance the degradation and mineralization of IMI in soil. By both the processes, there was an enhancement in the percentage degradation of IMI i.e 86.2% for PM and 94.6% for MP process. The obtained results indicate that MP process is apparently more efficient in degradation of IMI which was observed with 15 days of biological treatment followed by 18 h of photocatalytic degradation (15 d + 18 h). The present work also reveals that though the difference in terms of the degradation of IMI after 5 d + 18 h, 10 d + 18 h & 15 d+ 18 h of MP process is not drastic, yet significant variation has been observed in terms of mineralization that truly signifies the removal of IMI from the soil. The LC analysis has shown that the intermediates formed during MP process are more and smaller in comparison to PM process, which further provides evidence that MP process is better than PM process for effective degradation of IMI in soil.

Sequential Degradation Mechanism of Stationary PEMFC Under Dehydration Condition

With regard to increasing energy consumption, a polymer electrolyte membrane fuel cell (PEMFC) has received lots of attention due to its pollutant-free fuel and byproduct (water). There are lots of works to improve the performance and stability of PEMFC, however, there remains unsolved problem of long-term durability directly related to cost, which are caused by the corrosive environments inside the membrane-electrode assembly (MEA). In particular, both electrochemical corrosion and chemical deterioration result in a fast degradation of PEMFC, especially under the specific degradation conditions such as fuel starvation, flooding, dehydration, and on-off cycle. Among them, a study on dehydration condition becomes the most important as next-generation fuel cell system demands high temperature (low RH) in stack operation for better tolerance to CO and the simplified water management systems in PEMFC [1]. However, the previously reported degradation mechanisms under dehydration are mostly focused on the membrane decay and the electrochemical analyses were too conventional to elucidate the mechanism. Hence, in the present study we aim at performing sequential deconvolution of the degradation mechanism of PEMFC operating at 300 mA cm-2 under low humidity of RH 30%. During the dehydration degradation process, we conducted electrochemical measurements under both humidity condition: normal condition (RH 100%) and dry condition (RH 30%). In particular, electrochemical measurement under low humidity condition allows us to exclude the influence of the water as a proton transport medium (See Figure 1(a)) and subdivide specific resistance components from the profile of the Nyquist plots by increasing the ionic resistance deliberately in order to focus on only the intrinsic properties of membrane itself as shown in Figure 1(b). As shown in Figure 2(a-b), the current density at 0.7 V of cell voltage under RH 100 % condition decreases from 620.0 to 518.8 cm-2 during initial 300 h of degradation test and additional 300 h of procedure causes additional 17.2% decrement with the increase of charge transfer resistance. Even though these results show the degraded MEA under corrosive condition, these are not enough to identify the successive degradation components. As shown in Figure 2(c), the i-V curves measured under RH 30 % shows the performance also decrease during initial 300 h of degradation process with the increase of ionic resistance from 1.15 to 3.15 ohm cm2. However, after additional 300 h (total 600 h) the abnormal phenomenon showing the temporarily improved performance was confirmed with the decrease of ionic resistance from 3.15 to 1.9 ohm cm2 as shown in Figure 2(d). The unique characteristic could seem to be induced by a shorten proton diffusion path by the membrane thinning [2]. After operating at 300 mA cm-2 for more than 600 h at RH 30%, TEM surface analyses were conducted. As shown in Figure 3(a-e), the Pt particles were grown more largely on cathode than anode, which implies that reverse current decay (cathode carbon corrosion) occurs even in the dehydration degradation. In summary, the degradation mechanism under dehydration can be separately identified in sequential order: (1) ionomer degradation, (2) membrane thinning, and (3) reverse current decay.

Structural and Mechanistic Insights into Caffeine Degradation by the Bacterial N-Demethylase Complex

Caffeine, found in many foods, beverages, and pharmaceuticals, is the most used chemical compound for mental alertness. It is originally a natural product of plants and exists widely in environmental soil. Some bacteria, such as Pseudomonas putida CBB5, utilize caffeine as a sole carbon and nitrogen source by degrading it through sequential N-demethylation catalyzed by five enzymes (NdmA, NdmB, NdmC, NdmD, and NdmE). The environmentally friendly enzymatic reaction products, methylxanthines, are high-value biochemicals that are used in the pharmaceutical and cosmetic industries. However, the structures and biochemical properties of bacterial N-demethylases remain largely unknown. Here, we report the structures of NdmA and NdmB, the initial N1- and N3-specific demethylases, respectively. Reverse-oriented substrate bindings were observed in the substrate-complexed structures, offering methyl position specificity for proper N-demethylation. For efficient sequential degradation of caffeine, these enzymes form a unique heterocomplex with 3:3 stoichiometry, which was confirmed by enzymatic assays, fluorescent labeling, and small-angle x-ray scattering. The binary structure of NdmA with the ferredoxin domain of NdmD, which is the first structural information for the plant-type ferredoxin domain in a complex state, was also determined to better understand electron transport during N-demethylation. These findings broaden our understanding of the caffeine degradation mechanism by bacterial enzymes and will enable their use for industrial applications.