Protein-like Molecules Research Articles

Molecular features of uranium-binding natural organic matter in a riparian wetland determined by ultrahigh resolution mass spectrometry

Tims Branch riparian wetland located in South Carolina, USA has immobilized 94 % of the U released >50 years ago from a nuclear fuel fabrication facility. Sediment organic matter (OM) has been shown to play an important role in immobilizing U. Yet, uranium-OM-mineral interactions at the molecular scale have never been investigated at ambient concentrations. The objectives of this study were to extract, purify, and concentrate U-bound sediment OM along the stream water pathway and perform molecular characterization using Fourier transform ion cyclotron resonance mass spectrometry (FTICRMS). Out of 9614 identified formulas, 715 contained U. These U-containing formulas were enriched with Fe, N, and/or S compared to the total OM. Lignin-like and protein-like molecules accounted for 40 % and 19 % of the U-containing formulas, respectively. Phosphorus-containing formulas were found to exert an insignificant influence on complexing U. U-containing formulas in the ‘mobile’ (groundwater extractable) OM fraction had lower (reduced) nominal oxidation states of carbon (NOSC); and less aromatic moieties than OM recovered from the ‘immobile’ (sodium pyrophosphate extractable) OM fraction. U-containing formulas in the redox interfacial zones (stream banks) compared to those in nearby up-slope zones tended to have smaller molecular weights; lower NOSC; higher contents of COO and/or CONO functional groups; and higher abundance of Fe-containing formulas. Fe was present in 38 % of the U-containing formulas but only 20 % of the total OM formulas. It is postulated that Fe played an important role in stabilizing the structure of sedimentary OM, especially U-containing compounds. The identification for the first time of hundreds of Fe-U-OM formulas demonstrates the complexity of such system is much greater than commonly believed and numerically predicting U binding behavior in OM-rich systems may require greater use of statistical or artificial intelligence approaches rather than deterministic approaches limited to measuring metal complexation with well-defined individual analogue organic ligands.

Sampling terrigenous diffuse sources in watercourse: Influence of land use and hydrological conditions on dissolved organic matter characteristics

Diffuse and point sources of dissolved organic matter (DOM) in streams influence its composition, interactions and fate in the aquatic ecosystem. These inputs can be very numerous at the scale of a watershed, and their identification remains a challenge, especially for diffuse sources related to land use. The complexity of the transfer mechanisms and the reactivity of DOM throughout the soil-water column continuum raise questions about the sampling of diffuse sources in watercourses. To answer this issue, we compared the characteristics of soil-extracted DOM influenced by a particular land use (homogenous sub-catchment of forest and vineyard) and DOM collected from the watercourse adjacent to the soil samples. A 28-day incubation experiment of soil extracts was designed to remove the labile fraction of DOM. During the first 3 days, between 40 and 70 % of the DOC mass was lost for both types of soils. A set of optical indicators (UV–Visible, EEM fluorescence and HPSEC/UV-fluorescence) showed that the labile fraction was mostly composed by low (<1 kDa) and high (>10 kDa) protein-like molecules. At the end of the incubation, soil-extracted DOM was mainly composed of medium molecules (1–10 kDa) associated to terrigenous humic-like compounds. Its optical and size molecular signature tended towards that in the adjacent watercourses and was specific to land use. However, the characteristics of DOM in watercourses was also influenced by the hydrological conditions, probably due to a transfer of top soil DOM during high water periods and both deep soil and autochthonous DOM during low water periods. These results were obtained by a set of indicators, including novel ones derived from HPSEC/UV-fluorescence. Finally, this study demonstrated that it is possible to sample the DOM representative of a land use directly in the river downstream of the homogeneous sub-basin by multiplying the samples during contrasting hydrological conditions.

A Novel Design Method for Protein-Like Molecules from the Perspective of Sheaf Theory

A Novel Design Method for Protein-Like Molecules from the Perspective of Sheaf Theory

Molecular linkages between chemodiversity and MCPA complexation behavior of dissolved organic matter in paddy soil: Effects of land conversion

Complexation of dissolved organic matter (DOM) plays a crucial role in regulating the fate and risk of agrochemicals. Here, taking a toxic herbicide MCPA (4-chloro-2- methylphenoxyacetic acid) as the target, the effect of land conversion on complexation behavior of DOM to agrochemicals was investigated in paddy soil. Furthermore, the mechanisms were explored in a new perspective of DOM chemodiversity. Soil DOMs were selected from four long-term cropping systems, including paddy field (PF), vegetable field (VF), rice-vegetable rotation (RV) and abandoned land (AL). The results showed that the DOMs in PF and AL were rich in hydrophilic substances (e.g., carbohydrates or protein-like molecules) with low aromaticity. However, after converting PF to VF and RV, abundant aromatic macromolecules and aliphatic alkanes were observed in DOM. Due to those changes in DOM chemodiversity, the binding site and capability of DOM were highest in VF and RV, and were positively correlated with DOM aromaticity, MW, humus and polar groups (e.g., amino). This was because the complexation of “DOM-MCPA” was static binding via ligand exchange and H-bonding among polar groups and hydrophobic interaction among aromatic skeletons. The EEM-PARAFAC confirmed that microbial humic-like substances dominated the complexation of DOM rather than terrestrial humic-like and tryptophan-like matters. The 2D-COS analysis further revealed that the complexation of DOM preferentially occurred in amino, polysaccharide C–O and aliphatic C–H for PF and AL, but in aromatic C=C, amide C=N for RV and VF. In summary, these findings provide molecular insight into the effect of land conversion on DOM complexation activity, which highlight the importance of DOM chemodiversity. These results will contribute to the risk assessments of agrochemicals in paddy soil.

Transformation of dissolved organic matter during biological wastewater treatment and relationships with the formation of nitrogenous disinfection byproducts

Nitrogenous disinfection byproducts (N-DBPs) can be produced from dissolved organic matter (DOM) during the disinfection of secondary wastewater effluent. This study examined the transformation of DOM and the abatement of N-DBP precursors during different types of biological wastewater treatment (e.g., anaerobic/anoxic/oxic activated sludge processes and membrane bioreactor) using high-performance size exclusion chromatography (HPSEC) with dissolved organic carbon, UV, and fluorescence detectors. DOM with molecule weight (MW) larger than 3 kDa and protein-like substances smaller than 0.3 kDa was effectively bio-transformed, whereas DOM fractions with MW in the range of 0.3–3 kDa were the most bio-refractory. Complete nitrification was beneficial to the removal of small amino sugar-like and protein-like molecules (< 0.3 kDa). Haloacetonitrile (HAN) precursors were recalcitrant to biological treatment with a median removal of 17%. Halonitromethane (HNM) and N-nitrosamine (NA) precursors tended to be effectively removed in complete nitrification conditions. The abundance of low-molecular-size protein-like substances (< 0.3 kDa) was significantly correlated with the formation potential of HNM, NA, and total N-nitrosamine (TONO) in post-chloramination (r = 0.81, 0.62, and 0.68, respectively, p < 0.01). This study improved the understanding of DOM transformation and the removal of N-DBPs precursors in wastewater treatment and pointed out the benefit of provision of complete nitrification in removing low-molecular-size protein-like substances and NA and HNM precursors.

Process and mechanism between water-extracted organic matter and trace metallic ions in sediments of Yangtze River estuary

In order to better understand the bioavailability, toxicity, migration and transformation behaviors of trace metals in river estuary, this study deeply investigated the interactions between organic matters in sediments and trace metals. The results suggested that both protein-like molecules and marine humic acids could react with trace metals (Cu2+ and Cd2+). These two fluorescent substances fixed trace metals through carboxyl group, hydroxyl group, and phenol hydroxyl group, and protein-like molecules were more sensitive than marine humic acids. Moreover, Cu2+ possessed stronger binding ability and more active sites with both protein-like molecules and marine humic acids. Hence, Cd2+ exhibited higher environmental risks due to the higher migration and transformation. The thermodynamic results revealed that the reaction between WEOM and trace metals was spontaneous and exothermic, and low temperature was favorable for immobilization of Cu2+ or Cd2+.This study could help to understand environmental behaviors and impact of trace metals on the sediments of Yangtze River estuary.

Mixture of controlled-release and conventional urea fertilizer application changed soil aggregate stability, humic acid molecular composition, and maize nitrogen uptake

Controlled-release urea (CRU) fertilizer application has been shown to improve crop yield and nitrogen (N) use efficiency. However, its effects when mixed with conventional urea fertilizer on soil aggregate stability, humic acid (HA) molecular composition and crop N uptake remain unclear. Soil and plant samples were collected from a long-term (2008–2019) experiment on field maize (Zea mays L., ‘Zhengdan 958’) which included two types of fertilizers [conventional urea fertilizer (CUF), blended CUF with CRU fertilizer (CRF)], four N application rates (0, 150, 300 and 450 kg ha−1), each in three replicates. The results showed that at 300 kg N ha−1, compared to CUF treatment, the CRF treatment significantly improved soil aggregate characteristics [aggregate content with particle size larger than 0.25 mm (R0.25) by 9.6%, mean weight diameter by 19.8%, and geometric mean diameter by 21.7%]. CRF treatment also increased HA content by 5.5%, fulvic acid (FA) by 5.5%, lignin-like molecules by 0.94 times, and protein-like molecules by 3.69 times. At grain-filling stage, CRF treatments significantly increased the sum of soil NH4+-N and NO3−-N content by 23.3–24.5%, sap bleeding rate by 12.8–18.2% and N delivery rate through bleeding sap by 60.6–87.7% compared to CUF treatments at the same N application rate. At the same rate of N application, the CRF treatments significantly improved the average yield during three growing seasons by 9.4–14.0% in contrast with CUF treatments. The regression equations showed that the maximum yield was 8294 kg ha−1 for CUF at the application rate of 312 kg N ha−1 while it was 9890 kg ha−1 for CRF at the application rate of 286 kg N ha−1. We conclude that the long-term application of CRF changed the HA molecular structure, enhanced the water stable aggregates, improved crop N uptake, and increased economically viable maize yield.

The response mechanism of Hydrilla verticillata and leaf epiphytic biofilms to depth and nutrient removal.

The mechanism of morphological and physiological regulation of submerged aquatic plants (Hydrilla verticillata) is influenced by spatial and environmental changes related to water depth gradients. In the present study, changes in the aquatic microcosm were explored at the depth gradients of 0.3 m, 0.6 m, 0.9 m, 1.2 m, and 1.5 m, and the depth was recognized as a critical factor for improving water quality, especially for the removal of total phosphorus (TP) and recalcitrant protein-like molecules. At 0.9 m, the removal rates of TP and protein-like substances reached 78% and 18.67%, respectively, 1.76 times and 1.28 times the rates at 0.3 m. The maximum shoot/root growth and chlorophyll (a + b) suggest photosynthesis inhibition is minimal at 1.2 m. Fluctuations in enzyme activities imply an antioxidant response to lipid peroxidation damage under different oxidative stress. The adjusted activities of glutamine synthetase (GS) and alkaline phosphatase (APA) were an adaptive nutrient utilization strategy to different water depths. Microbiological diversity analysis of biofilms indicates that community structure changes in response to water depth. Considering the growth status and nutrient removal effects, the results indicate that the optimal planting depth for H. verticillata is 0.9-1.2 m. These findings contribute to understanding water purification mechanisms in depth gradients, and support the effective rebuilding and management of submerged macrophyte communities in natural shallow lakes.

A proctolin-like peptide is regulated after baculovirus infection and mediates in caterpillar locomotion and digestion.

Baculoviruses constitute a large group of invertebrate DNA viruses, predominantly infecting larvae of the insect order Lepidoptera. During a baculovirus infection, the virus spreads throughout the insect body producing a systemic infection in multiple larval tissues, included the central nervous system (CNS). As a main component of the CNS, neuropeptides are small protein-like molecules functioning as neurohormones, neurotransmitters, or neuromodulators. These peptides are involved in regulating animal physiology and behavior and could be altered after baculovirus infection. In this study, we have investigated the effect of Spodoptera exigua multiple nucleopolyhedrovirus (SeMNPV) infection on expression of Spodoptera exigua neuropeptides and neuropeptide-like genes. Expression of the gene encoding a polypeptide that resembles the well-known insect neuropeptide proctolin and named as proctolin-like peptide (PLP), was downregulated in the larval brain following infection and was chosen for further analysis. A recombinant Autographa californica multiple nucleopolyhedrovirus (AcMNPV) overexpressing the C-terminal part of the PLP was generated and used in bioassays using S. exigua larvae to study its influence on the viral infection and insect behavior. AcMNPV-PLP-infected larvae showed less locomotion activity and a reduction in growth compared to larvae infected with wild type AcMNPV or mock-infected larvae. These results are indicative of this new peptide as a neuromodulator that regulates visceral and skeletal muscle contractions and offers a novel effector involved in the behavioral changes during baculovirus infection.

Dissolved Organic Matter in Continental Hydro-Geothermal Systems: Insights from Two Hot Springs of the East African Rift Valley

Little is known about the quantity and quality of dissolved organic matter (DOM) in waters from continental geothermal systems, with only a few reports available from the Yellowstone US National Park. In this study, we explored the chemodiversity of DOM in water samples collected from two geothermal hot springs from the Kenyan East African Rift Valley, a region extremely rich in fumaroles, geysers, and spouting springs, located in close proximity to volcanic lakes. The DOM characterization included in-depth assessments performed by negative electrospray ionization Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR-MS). Reduced, saturated and little aromatic DOM compounds were dominant in the hot spring waters collected from either the Ol Njorowa gorge (ON) or the south shore of the soda-saline Lake Elementaita (ELM). Oxygen-poor and sulfur-bearing DOM molecules prevailed in ON, probably reflecting abiotic sulfurization from sulfide-rich geofluids. Nitrogen-bearing aliphatic and protein-like molecules were abundant in ELM, possibly perfusing through the organic-rich sediments of the adjacent Lake Elementaita. Notably, the heat-altered DOM of ancient autochthonous derivation could represent an overlooked source of aliphatic organic carbon for connected lentic environments, with a potential direct impact on nutrient cycling in lakes that receive geothermal water inputs.

Strong mineralogic control of soil organic matter composition in response to nutrient addition across diverse grassland sites

Soil organic matter (SOM) dynamics are central to soil biogeochemistry and fertility. The retention of SOM is governed initially by interactions with minerals, which mediate the sorption of chemically diverse organic matter (OM) molecules via distinct surface areas and chemical functional group availabilities. Unifying principles of mineral-OM interactions remain elusive because of the multi-layered nature of biochemical-mineral interactions that contribute to soil aggregate formation and the heterogeneous nature of soils among ecosystems. This study sought to understand how soil mineralogy as well as nitrogen (N) enrichment regulate OM composition in grassland soils. Using a multi-site grassland experiment, we demonstrate that the composition of mineral-associated OM depended on the clay content and specific mineral composition in soils across the sites. With increasing abundance of ferrihydrite (Fh) across six different grassland locations, OM in the hydrophobic zone became more enriched in lipid- and protein-like compounds, whereas the kinetic zone OM became more enriched in lignin-like molecules. These relationships suggest that the persistence of various classes of OM in soils may depend on soil iron mineralogy and provide experimental evidence to support conceptual models of zonal mineral-OM associations. Experimental N addition disrupted the accumulation of protein-like molecules in the hydrophobic zone and the positive correlation of lignin-like molecules in the kinetic zone with Fh content, compared to unfertilized soils. These data suggest that mineralogy and clay content together influence the chemical composition not only of mineral-associated OM, but also of soluble compounds within the soil matrix. If these relationships are prevalent over larger spatial and temporal scales, they provide a foundation for understanding SOM cycling and persistence under a variety of environmental contexts.

Roles of quantum interference in modulating the spin-polarized transport induced by single-helical molecules

We investigate the spin-polarized transport through the systems with protein-like single-helical molecules. It shows that the spin polarization property and efficiency tightly depend on the geometries of the systems of single-helical molecules. When one molecule is serially coupled to two leads, the inter-lead coupling assists to magnify the spin polarization efficiency, and the polarization direction can be adjusted by the local magnetic flux. However in the other geometries, no apparent spin polarization is driven, such as the T-shaped structure with inter-lead coupling and parallel coupled structures. These results reflect the nontrivial effect of structure-dependence quantum interference on the spin polarization driven by the single-helical molecule.

Photochemical production of hydroxyl radical from algal organic matter

Photochemical production of hydroxyl radical (·OH) from algal organic matter (AOM) collected from Lake Torrens in South Australia was examined using a sunlight simulator. The two AOM isolates featured lower molecular weight, lower chromophoric content, and lower SUVA254 (0.7 and 0.9, L mgC−1 m−1) than the reference Suwannee River hydrophobic acid (SR-HPO), they had considerably higher apparent quantum yields (ϕNOMOH, 3.03 × 10−5 and 2.18 × 10−5) than SR-HPO (0.84 × 10−5). Fluorescence excitation-emission matrix (FEEM) showed that the major components in the AOM were aromatic protein-like and soluble microbial substances. Unique formulas of the two AOM isolates as compared to SR-HPO were revealed using FTICR-MS and classified into four areas, namely protein-like molecules with low O/C (H/C > 1.5, O/C: 0.2–0.4), lignin-derived moieties with low O/C (H/C:1.0–1.5, O/C: 0.1–0.3), protein-like molecules with high O/C (H/C > 1.5, O/C: 0.5–0.7), and carbohydrate derivatives (H/C > 1.5, O/C > 0.7). These unique AOM moieties characterised utilizing FEEM and FTICR-MS were tentatively postulated to contribute to the high ϕNOMOH. To the best of our knowledge, this is the first study performed to both evaluate natural AOM as an efficient photosensitiser of ·OH and propose AOM moieties responsible for the high ϕNOMOH.

Colloidal stability of Fe3O4 magnetic nanoparticles differentially impacted by dissolved organic matter and cations in synthetic and naturally-occurred environmental waters

Better understanding of the colloidal behaviors of nanomaterials impacted by aquatic chemistry parameters is needed for appropriate evaluation of the environmental risks posed by nanomaterials in natural waters. In the study, the colloidal stability of Fe3O4 magnetic nanoparticles (Fe-MNPs) was evaluated over a range of chemistry characteristics [e.g., pH, dissolved organic matter (DOM), salt types, cationic strength] in six synthetic water samples. The findings from the synthetic water samples were further examined with eight “real world” environmental water samples. Our results demonstrated that DOM fraction, humic acid (HA), promoted suspension of Fe-MNPs more by hydrophobic interactions in addition to ligand exchange and electrostatic effects compared with fulvic acid (FA). Capability of cations to increase aggregation of Fe-MNPs were in the order of Ca2+ > Mg2+ >> Na+ because of their different degrees of bridging complexation with DOM molecules on particle surfaces. As a key parameter for indicating Fe-MNPs colloidal stability, Zeta (ζ) potentials of Fe-MNPs in these waters samples were well correlated to (R2 = 0.880, P < 0.001) the contents, types and adsorption forms of DOM and cations. However, several other factors could also affect the hydrodynamic diameter (HDD) of Fe-MNPs in the “real world” environmental waters. It assumed that ampholytic-DOM molecules such as amino acid- and protein-like molecules caused great aggregation of Fe-MNPs. These findings would be helpful for better understanding and evaluating the colloidal behaviors of nanomaterials when they released into natural water environment, thus could shed light on developing relevant pollution control strategies.

Evaluation of β-Amino Acid Replacements in Protein Loops: Effects on Conformational Stability and Structure.

β-Amino acids have a backbone that is expanded by one carbon atom relative to α-amino acids, and β residues have been investigated as subunits in protein-like molecules that adopt discrete and predictable conformations. Two classes of β residue have been widely explored in the context of generating α-helix-like conformations: β3 -amino acids, which are homologous to α-amino acids and bear a side chain on the backbone carbon adjacent to nitrogen, and residues constrained by a five-membered ring, such the one derived from trans-2-aminocyclopentanecarboxylic acid (ACPC). Substitution of α residues with their β3 homologues within an α-helix-forming sequence generally causes a decrease in conformational stability. Use of a ring-constrained β residue, however, can offset the destabilizing effect of α→β substitution. Here we extend the study of α→β substitutions, involving both β3 and ACPC residues, to short loops within a small tertiary motif. We start from previously reported variants of the Pin1 WW domain that contain a two-, three-, or four-residue β-hairpin loop, and we evaluate α→β replacements at each loop position for each variant. By referral to the ϕ,ψ angles of the native structure, one can choose a stereochemically appropriate ACPC residue. Use of such logically chosen ACPC residues enhances conformational stability in several cases. Crystal structures of three β-containing Pin1 WW domain variants show that a native-like tertiary structure is maintained in each case.

Quantum-interference effect on the spin polarization driven by protein-like single-helical molecules

We report a theoretical study about the spin-dependent electron transport through a two-arm mesoscopic circuit in which two protein-like single-helical molecules connect serially with two normal metallic leads, respectively. Based on an effective-model Hamiltonian, the spin polarization is evaluated using the Landauer–Buttiker formula. Our results reveal that in comparison with the single-arm case, the spin-polarization efficiency can be enhanced in this system, by adjusting the length ratio of two molecules and the molecule–lead coupling manner. Besides, when local magnetic flux is introduced, the Aharonov–Bohm effect makes a nontrivial contribution to the spin polarization. These findings can be helpful for building the helical-molecule-based spin filters.

Highly-polarized spin currents through protein-like single-helical molecules

Electronic transport through a protein-like single-helical molecule is theoretically studied. By introducing an additional terminal to couple to the molecule, we construct a two-channel mesoscopic circuit, and then calculate the charge and spin currents in the two drain terminals. It is found that in one drain terminal, one pure spin current has an opportunity to appear without any accompanying charge current. Besides, the polarization direction of the spin current can be inverted. With respect to the current in the other drain, it is also found to be highly polarized, with its polarization direction different from that in the other terminal. These results suggest that the protein-like single-helical molecule is a promising candidate for building the two-channel setup in spintronics.

Dynamic changes of dissolved organic matter in membrane bioreactors at different organic loading rates: Evidence from spectroscopic and chromatographic methods

Excitation emission matrix-parallel factor analysis (EEM-PARAFAC) and size exclusion chromatography (SEC) were utilized to explore the dynamics in extracellular polymeric substances (EPS), soluble microbial products (SMP), and effluent for the membrane bioreactors at two different organic loading rates (OLRs). Combination of three different fluorescent components explained the compositional changes of dissolved organic matter. The lower OLR resulted in a higher production of tryptophan-like component (C1) in EPS, while the opposite trends were found for the other two components (humic-like C2 and tyrosine-like C3), signifying the role of C1 in the endogenous condition. Larger sized molecules were more greatly produced in EPS at the lower OLR. Meanwhile, all the size fractions of SMP were more abundant at the higher OLR particular for the early phase of the operation. Irrespective of the OLR, the higher degrees of the membrane retention were found for relatively large sized and protein-like molecules.

Enhancement of spin polarization in transport through protein-like single-helical molecules

We investigate the spin-polarized electron transport through the single-helical molecules connected with two normal metallic leads. On the basis of an effective model Hamiltonian, influences of the structural parameters on the conductance and the spin polarization are calculated by using the Landauer–Buttiker formula. The optimal structural parameters for the maximal spin polarization are analyzed. Our results show that the dephasing term is an important factor to enhance the spin polarization, in addition to the intrinsic parameters of the single-helical molecule. This work can be helpful in optimizing the spin polarization in the protein-like single-helical molecules.

Removal of emerging micropollutants from wastewater by activated carbon adsorption: Experimental study of different activated carbons and factors influencing the adsorption of micropollutants in wastewater

Activated carbon processes, initially designed for drinking water production, are tested for wastewater application in order to characterize their efficiency to remove micropollutants from wastewater treatment plants (WWTPs) discharges. In that purpose, a pilot was studied by the Paris sanitation service (SIAAP) and the water environment and urban systems laboratory (LEESU). The in-situ study raised several additional questions related to the structural and morphological properties of activated carbons, in order to select the proper material, the influence of operational parameters such as the activated carbon dose and the contact time, the role of organic matter concentration and composition, the presence of a residual concentration of methanol or the impact of ferric chloride addition. Thus, various complementary experiments were carried out at laboratory scale to improve the understanding of the micropollutants adsorption process on activated carbon, in particular on powdered activated carbon (PAC).The results have highlighted a strong link between the efficiency of PACs and their specific surface (BET), which can be easily estimated by their bulk density. The study of the sorption process has also confirmed the strong influence of the PAC dose and the rapidity of the sorption kinetic. From an operational point of view, the ferric chloride injection seems to slightly improve most of the detected compounds adsorption, probably thanks to the coagulation of the dissolved organic matter colloidal fraction. In contrary, the presence in the water of a residual concentration of methanol seems to have no impact on the micropollutant fate. The influence of the wastewater matrix is strong, with notably lower adsorption in water from primary settling compared to various WWTP discharges. However, the dissolved organic carbon concentration is not always sufficient to explain sorption competitions in wastewater, and the nature of the organic matter should be considered too. In particular, the carbon removal from biological treatments is the step that clearly modifies both the quantity and the composition of the organic matter. It has been observed that discharges from WWTPs operating with different biological processes (activated sludge, membrane bioreactor or biofiltration) have similar organic matter concentrations and compositions, and allows comparable removals of organic matter and micropollutants by adsorption. The lower performances on micropollutants observed in the settled water can be explained by the higher quantity of protein-like molecules (fluorophores Iδ and Iγ), which compose the most competitive organic matter fraction for adsorption on activated carbon, compared to the other waters.