Strong Binding Sites Research Articles

Covalent organic framework nanorods bearing single Cu sites for efficient photocatalysis

Covalent organic frameworks (COFs) nanostructures capable of efficient visible light absorption, complete holes-electrons separation, and reactant enrichment remain a synthetic challenge for advanced photocatalysts. Herein, we rationally design a novel Cu-coordinated terpyridyl-based, 2D lamellar COF-909(Cu) nanorods. The coordinated single Cu sites not only dramatically enhance the visible light absorption and achieve the complete electrons-holes separation, but also provide the specific binding sites to enrich N/O-containing organic toxicants. The laminar arrangement and 1D nanochannel of COF-909(Cu) nanorods shorten the transfer distance of electrons to the active sites. As a proof of concept, it shows excellent performance in the photocatalytic degradation of sulfamethoxazole, which surpasses the-state-of-art photocatalysts. Density functional theory calculations confirm the structure-function relationship between the single Cu sites and the complete electrons-holes separation as well as strong binding sites for target molecules.

Isolation, characterization, and hepatoprotective properties of betulinic acid and ricinine from Tetracarpidium conophorum seeds (Euphorbiaceae).

The present study is to isolate and characterize betulinic acid and ricinine from T. conophorum seeds. Phytochemical investigation on hexane fraction of T. conophorum seeds led to the isolation of two compounds, Betulinic acid (1), and Ricinine (2). Betulinic acid and ricinine were screened against HepG2 cells and tested in vivo in CCl4 -induced experimental rats model. Results from this study showed that the compounds had hepatoprotective and cytotoxic activities. It was observed that betulinic acid inhibited HepG2 cell with percentage inhibition of 54% compared with standard doxorubicin (64%), while ricinine was inactive against HepG2 cell lines. Furthermore, molecular docking was carried out on betulinic acids and ricinine, with binding energies of -11.2kcal/mol and -5.4kcal/mol, respectively, indicating strong binding sites and interactions with Hepatitis B Virus DNA polymerase. Therefore, findings from this study suggest that betulinic acid possess cytotoxic and hepatoprotective properties, while ricinine exhibited hepatoprotection in CCl4 -induced liver damage. PRACTICAL APPLICATIONS: Medicinal plants contain unrestricted ability to make compounds that intrigue researchers in the quest for novel phyto-therapeutic drugs. The continuous exploration of new compounds in the medicinal plant is an auspicious strategy for the prevention of diseases. Therefore, the purpose of this research is to evaluate the cytotoxic and hepatoprotective compounds (betulinic acid and ricinine) isolated from T. conophorum seeds.

Optimizing Pore Space for Flexible-Robust Metal-Organic Framework to Boost Trace Acetylene Removal.

Isoreticular principle has been employed to realize a flexible-robust metal-organic framework (MOF) with extended pore structure for the adsorptive removal of trace acetylene from ethylene under ambient conditions. The substitution from zinc(II) to copper(II) of high coordination distortion leads to elongated Cu-F bonds that expand the closed pore cavities in the prototypical MOF from 3.5 × 3.9 × 4.1 to 3.6 × 4.3 × 4.2 Å3. The optimal cavity size together with strong binding sites thus endows the new Cu analogue to possess open pore space accessible for trace C2H2 within a substantial low-pressure range while excluding C2H4 molecules, as validated by gas isotherms and single-crystal structure of its partially C2H2-loading phase. In contrast to the Zn prototype, at 298 K and 1.0 bar, the guest-free Cu analogue shows significant C2H2 uptake increase with a total capacity of 4.57 mmol g-1, and gains an over two orders of magnitude jump in IAST selectivity for C2H2/C2H4 (1/99, v/v). These results are higher than the benchmark MOFs for molecular sieving of C2H2/C2H4, leading a high C2H4 productivity of 14.9 mmol g-1. Crystallography studies, molecular modeling, selectivity evaluation, and breakthrough experiments have comprehensively demonstrated this flexible-robust MOF as an efficient adsorbent for C2H2/C2H4 separation.

Multiple weak interactions between BvgA~P and ptxpromoter DNA strongly activate transcription of pertussis toxin genes in Bordetella pertussis.

Pertussis toxin is the preeminent virulence factor and major protective antigen produced by Bordetella pertussis, the human respiratory pathogen and etiologic agent of whooping cough. Genes for its synthesis and export are encoded by the 12 kb ptx-ptl operon, which is under the control of the pertussis promoter, Pptx. Expression of this operon, like that of all other known protein virulence factors, is regulated by the BvgAS two-component global regulatory system. Although Pptx has been studied for years, characterization of its promoter architecture vis-à-vis BvgA-binding has lagged behind that of other promoters, mainly due to its lower affinity for BvgA~P. Here we take advantage of a mutant BvgA protein (Δ127–129), which enhances ptx transcription in B. pertussis and also demonstrates enhanced binding affinity to Pptx. By using this mutant protein labeled with FeBABE, binding of six head-to-head dimers of BvgA~P was observed, with a spacing of 22 bp, revealing a binding geometry similar to that of other BvgA-activated promoters carrying at least one strong binding site. All of these six BvgA-binding sites lack sequence features associated with strong binding. A genetic analysis indicated the degree to which each contributes to Pptx activity. Thus the weak/medium binding affinity of Pptx revealed in this study explains its lower responsiveness to phosphorylated BvgA, relative to other promoters containing a high affinity binding site, such as that of the fha operon.

Insights into the interaction of iodide and iodine with Cu(II)-loaded bispicolylamine chelating resin and applications for nuclear waste treatment

Radioiodine is a challenging contaminant to remove from aqueous wastestreams, resulting from spent nuclear fuel reprocessing. To create a selective, economical adsorbent, a Cu-loaded bispicolylamine chelating resin was produced, from commercially available reagents and its performance for removal of aqueous iodide and iodine was assessed. The resin possessed a large equilibrium uptake capacity of 305 ± 14 mg.g−1 iodide and 2940 ± 180 mg.g−1 total iodine. Performance was close to maximal over a pH range of 2–10. Capacity was reduced by ~55% by the addition of cocontaminants nitrate and molybdate, but resistance to suppression was greatly superior to non-modified polyamine resins, clearly seen in dynamic column experiments. The uptake mechanism was investigated spectroscopically and was found to proceed via ligand-exchange, with some in-situ REDOX chemistry occurring, resulting in the formation of Cu(I) and triiodide. The latter was concurrently adsorbed on to the resin and occupied both strong (Cu-associated) and weak (charge-transfer complex formation) binding sites. Thermal decomposition of the loaded resins revealed that the captured iodine was volatised at several different temperatures, according to strength of adsorption, but a large fraction was converted to stable CuI, suggesting a possible pathway towards volume-reduction and immobilisation as a final wasteform.

Halogen-C2 H2 Binding in Ultramicroporous Metal-Organic Frameworks (MOFs) for Benchmark C2 H2 /CO2 Separation Selectivity.

Acetylene (C2 H2 ) capture is a step in a number of industrial processes, but it comes with a high-energy footprint. Although physisorbents have the potential to reduce this energy footprint, they are handicapped by generally poor selectivity versus other relevant gases, such as CO2 and C2 H4 . In the case of CO2 , the respective physicochemical properties are so similar that traditional physisorbents, such as zeolites, silica, and activated carbons cannot differentiate well between CO2 and C2 H2 . Herein, we report that a family of three isostructural, ultramicroporous (<7 Å) diamondoid metal-organic frameworks, [Cu(TMBP)X] (TMBP=3,3',5,5'-tetramethyl-4,4'-bipyrazole), TCuX (X=Cl, Br, I), offer new benchmark C2 H2 /CO2 separation selectivity at ambient temperature and pressure. We attribute this performance to a new type of strong binding site for C2 H2 . Specifically, halogen⋅⋅⋅HC interactions coupled with other noncovalent in a tight binding site is C2 H2 specific versus CO2 . The binding site is distinct from those found in previous benchmark sorbents, which are based on open metal sites or electrostatic interactions enabled by inorganic fluoro or oxo anions.

Potent reduction of plasma lipoprotein (a) with an antisense oligonucleotide in human subjects does not affect ex vivo fibrinolysis

It is postulated that lipoprotein (a) [Lp(a)] inhibits fibrinolysis, but this hypothesis has not been tested in humans due to the lack of specific Lp(a) lowering agents. Patients with elevated Lp(a) were randomized to antisense oligonucleotide [IONIS-APO(a)Rx] directed to apo(a) (n = 7) or placebo (n = 10). Ex vivo plasma lysis times and antigen concentrations of plasminogen, factor XI, plasminogen activator inhibitor 1, thrombin activatable fibrinolysis inhibitor, and fibrinogen at baseline, day 85/92/99 (peak drug effect), and day 190 (3 months off drug) were measured. The mean ± SD baseline Lp(a) levels were 477.3 ± 55.9 nmol/l in IONIS-APO(a)Rx and 362.1 ± 89.9 nmol/l in placebo. The mean± SD percentage change in Lp(a) for IONIS-APO(a)Rx was -69.3 ± 12.2% versus -5.4 ± 6.9% placebo (P < 0.0010) at day 85/92/99 and -15.6 ± 8.9% versus 3.2 ± 12.2% (P = 0.003) at day 190. Clot lysis times and coagulation/fibrinolysis-related biomarkers showed no significant differences between IONIS-APO(a)Rx and placebo at all time points. Clot lysis times were not affected by exogenously added Lp(a) at concentrations up to 200 nmol/l to plasma with very low (12.5 nmol/l) Lp(a) levels, whereas recombinant apo(a) had a potent antifibrinolytic effect. In conclusion, potent reductions of Lp(a) in patients with highly elevated Lp(a) levels do not affect ex vivo measures of fibrinolysis; the relevance of any putative antifibrinolytic effects of Lp(a) in vivo needs further study.

Arsenic(V) sorption kinetics in long-term arsenic pesticide contaminated soils

Historic As contamination of soils occurs throughout the world from mining, industrial and agricultural activities. Sorption processes and rate may strongly influence soil As mobility, which further influences As bioavailability and toxicity. We investigated the kinetics of As(V) sorption by adding the arsenic onto both pristine (non-contaminated) and historically contaminated soils from arsenicals in two contrasting soil types (ferralitic and sandy). Results suggest both pseudo-second order (PSO) and Elovich kinetic models produce robust correlations with good data fits to linearized plots (R2 ≈ 0.900–0.999) that describe the arsenic sorption kinetics for both contaminated and pristine soils. The arsenic sorption data are generally best described by the Elovich model with smaller normalized standard deviations (Δq <5%) than PSO model. In addition, the surface binding to exchangeable and specific sorption of fresh arsenic (63–96%) sites has an impact on the overall low rate of As(V) sorption in the aged contaminated soils. Pristine soils “particularly ferralitic soils” show intra-particle diffusion and/or surface precipitation, which can contribute to a greater irreversibility of As(V) binding in soil. In contrast, the As(V) sorption occurred in the pristine sandy soil in a similar fashion to that of the aged contaminated soil, most likely due to both soil groups having limited strong binding sites. The detailed knowledge from this study provides new insights into the reclamation and management of As contaminated sites.

Imine-Rich Poly( o -phenylenediamine) as High-Capacity Trifunctional Organic Electrode for Alkali-Ion Batteries

Alkali-ion batteries, including potassium-ion batteries, lithium-ion batteries, and sodium-ion batteries are important energy storage devices; however, with the cation size increased, there exists ...

Assessing the uranium DGT-available fraction in model solutions

The uranium speciation in humic acid (HA) and fulvic acid (FA) model solutions was investigated by diffusive gradients in thin films (DGT). A reference solution was used to normalize the DGT data from different samples. This approach was used to assess uranium DGT-available fraction (FU), which was calculated from experimental data and reflect both the mobility and lability of uranium species. FU decreased with increasing HA or FA concentrations, because more uranium was able to bind the strong binding sites of HA or FA. When copper was spiked, FU increased due to the competition between copper and uranium. In HA model solutions, an increase of ionic strength could increase FU, and when pH was greater than 7, FU increased significantly. The DGT uptake factor (φ), which can be obtained from data fitting, is the ratio of the product of diffusion coefficient and lability degree of the unknown sample to that of the reference solution. In U-HA-NaHCO3 solutions, UO2(CO3)22− had a relatively high φ value and might be the most DGT-available species. This approach allows the comparison of DGT data from different samples, and combining with a data fitting procedure, it can be used to investigate the distribution of metal species.

Pseudogene Associated Recurrent Gene Fusion in Prostate Cancer

We present the functional characterization of a pseudogene associated recurrent gene fusion in prostate cancer. The fusion gene KLK4-KLKP1 is formed by the fusion of the protein coding gene KLK4 with the noncoding pseudogene KLKP1. Screening of a cohort of 659 patients (380 Caucasian American; 250 African American, and 29 patients from other races) revealed that the KLK4-KLKP1 is expressed in about 32% of prostate cancer patients. Correlative analysis with other ETS gene fusions and SPINK1 revealed a concomitant expression pattern of KLK4-KLKP1 with ERG and a mutually exclusive expression pattern with SPINK1, ETV1, ETV4, and ETV5. Development of an antibody specific to KLK4-KLKP1 fusion protein confirmed the expression of the full-length KLK4-KLKP1 protein in prostate tissues. The in vitro and in vivo functional assays to study the oncogenic properties of KLK4-KLKP1 confirmed its role in cell proliferation, cell invasion, intravasation, and tumor formation. Presence of strong ERG and AR binding sites located at the fusion junction in KLK4-KLKP1 suggests that the fusion gene is regulated by ERG and AR. Correlative analysis of clinical data showed an association of KLK4-KLKP1 with lower preoperative PSA values and in young men (<50 years) with prostate cancer. Screening of patient urine samples showed that KLK4-KLKP1 can be detected noninvasively in urine. Taken together, we present KLK4-KLKP1 as a class of pseudogene associated fusion transcript in cancer with potential applications as a biomarker for routine screening of prostate cancer.

Cutting Edge: Tcf1 Instructs T Follicular Helper Cell Differentiation by Repressing Blimp1 in Response to Acute Viral Infection.

Differentiation of T follicular helper (TFH) cells is regulated by a complex transcriptional network, with mutually antagonistic Bcl6-Blimp1 as a core regulatory axis. It is well established that Tcf1 acts upstream of Bcl6 for its optimal induction to program TFH cell differentiation. In this study, we show that whereas genetic ablation of Tcf1 in mice greatly diminished TFH cells in response to viral infection, compound deletion of Blimp1 with Tcf1 restored TFH cell frequency, numbers, and generation of germinal center B cells. Aberrant upregulation of T-bet and Id2 in Tcf1-deficient TFH cells was also largely rectified by ablating Blimp1. Tcf1 chromatin immunoprecipitation sequencing in TFH cells identified two strong Tcf1 binding sites in the Blimp1 gene at a 24-kb upstream and an intron-3 element. Deletion of the intron-3 element, but not the 24-kb upstream element, compromised production of TFH cells. Our data demonstrate that Tcf1-mediated Blimp1 repression is functionally critical for safeguarding TFH cell differentiation.

Carboxylation as an effective approach to improve the adsorption performance of graphene materials for Cu2+ removal

Graphene materials are high-performance adsorbents for water and soil remediation, whose oxygen containing groups bind to metal ions intensely. In this study, we prepared carboxylated graphene oxide (GO-OCH2COOH) sponge and investigated the adsorption behaviors of Cu2+ on it by both experimental and computational approaches. Carboxylation largely improved the adsorption capacity from 23.8mg/g for graphene oxide (GO) sponge to 93.8mg/g for GO-OCH2COOH. The efficient adsorption was due to the strong interaction between Cu2+ and carboxyl groups (especially in –OCH2COOH form) according to the density functional theory calculation, while epoxy and hydroxyl groups contributed lowly. The fast adsorption process was achieved within 30min, corresponding to a large k2 value of pseudo-second order model (0.061mg/g/min). The adsorption was spontaneous and exothermic according to thermodynamics analyses. The binding strength of Cu2+ on GO-OCH2COOH was so strong that pH and ionic strength had mild impact. The strong binding sites were not recyclable, but the weaker ones (more than 40%) could be regenerated by simple washing. Our results highlighted the importance of chemical design in graphene adsorbents and the potential of GO-OCH2COOH in heavy metal fixation from water and soil.

Effect of the desiccation tolerance and cryopreservation methods on the viability of Citrus limon L. Burm cv. Eureka seeds

Cryopreservation of the germplasm for long-term periods is of great importance to maintain the genetic resource. Argentina is one of the world's highest lemon producing country. The performance of different cooling/warming rates in the cryopreservation method of Citrus limon L. Burm cv. Eureka seeds and their influence on the interval of optimal moisture content in the desiccation stage were analyzed. Water sorption isotherm was determined and modeled using D'Arcy & Watt equation; it provided important information concerning the amounts of water associated to strong, weak and multimolecular binding sites along the sorption isotherm. Seeds tolerated a wide range of desiccation conditions (0.1<aw<0.85) showing a high viability (>80%), however desiccation to 0.0526 g H2O g−1 d.b. (aw = 0.0901) produced a significant loss of viability. Differential Scanning Calorimetry was used to identify the thermal transitions of lipids and water in the seed; enthalpies were used to calculate the unfrozen water fraction (0.19 g H2O g−1 d.b. corresponding to aw = 0.64). Two cooling/warming rates were tested on desiccated seeds (0.11<aw<0.85): i) 200 °C min−1 (reached with seeds placed inside a closed cryogenic vial); ii) 1000 °C min−1 (reached with aluminum-foiled seeds placed in a perforated cryogenic vial). For both methods, viability was maximum (83.3%) at aw = 0.64. Lethal ice formation was responsible for the loss of viability at aw>0.64 corresponding to the unfrozen water fraction. The use of higher cooling/warming rates enables a wider range of desiccation conditions (0.33<aw<0.76) in cryopreservation procedures. This work contributes to the optimization of cryopreservation methods of economically important germplasm.

Carboxymethyl cellulose gel membrane loaded with nanoparticle photocatalysts for hydrogen production

Abstract Carboxymethyl cellulose (CMC) gel membranes were prepared by a chemical crosslinking method and an in situ method was used to load CdS nanoparticles with an average size of about 3 nm into the CMC gel. The negative ion groups in the CMC serve as strong binding sites for the metal ions and help prevent aggregation of the CdS nanoparticles during their growth process. This results in a CMC gel matrix loaded with stable and well-dispersed CdS nanoparticles (CdS-CMC). Pt co-catalyst particles were also loaded into the gel membrane to give CdS/Pt-CMC and both materials were used as photocatalysts for the production of hydrogen. The CdS/Pt-CMC catalyst with 5 wt % Pt exhibited a H2 evolution rate of 1365 μmol h−1 g−1, which is 81 times that of pure CdS. This improvement can be attributed to the separation of the CdS photo-generated electron-hole pairs. The photo-electrons are transferred to Pt and the formed aqueous H+ ions are then rapidly converted to H2. The incorporation of the photocatalyst into a gel matrix makes the photocatalyst easily recoverable which can help avoid environmental pollution caused by free CdS nanoparticles.

Analyzing the structural and functional roles of residues from the ‘black’ and ‘gray’ clusters of human S100P protein

Two highly conserved structural motifs observed in members of the EF-hand family of calcium binding proteins. The motifs provide a supporting scaffold for the Ca2+ binding loops and contribute to the hydrophobic core of the EF-hand domain. Each structural motif represents a cluster of three amino acids called cluster I (‘black’ cluster) and cluster II (‘grey’ cluster). Cluster I is more conserved and mostly incorporates aromatic amino acids. In contrast, cluster II is noticeably less conserved and includes a mix of aromatic, hydrophobic, and polar amino acids of different sizes. In the human calcium binding S100 P protein, these ‘black’ and ‘gray’ clusters include residues F15, F71, and F74 and L33, L58, and K30, respectively. To evaluate the effects of these clusters on structure and functionality of human S100 P, we have performed Ala scanning. The resulting mutants were studied by a multiparametric approach that included circular dichroism, scanning calorimetry, dynamic light scattering, chemical crosslinking, and fluorescent probes. Spectrofluorimetric Ca2+-titration of wild type S100 P showed that S100 P dimer has 1–2 strong calcium binding sites (K1 = 4 × 106 M−1) and two cooperative low affinity (K2 = 4 × 104 M−1) binding sites. Similarly, the S100 P mutants possess two types of calcium binding sites. This analysis revealed that the alanine substitutions in the clusters I and II caused comparable changes in the S100 P functional properties. However, analysis of heat- or GuHCl-induced unfolding of these proteins showed that the alanine substitutions in the cluster I caused notably more pronounced decrease in the protein stability compared to the changes caused by alanine substitutions in the cluster II. Opposite to literature data, the F15 A substitution did not cause the S100 P dimer dissociation, indicating that F15 is not crucial for dimer stability. Overall, similar to parvalbumins, the S100 P cluster I is more important for protein conformational stability than the cluster II.

Antidiabetic, antioxidant, molecular docking and HPTLC analysis of miquelianin isolated from Euphorbia schimperi C. Presl

The present study demonstrates the miquelianin or quercetin 3-O-glucuronide (compound 1) isolated from aerial parts of Euphorbia schimperi exhibited significant results for antioxidant and antidiabetic potential. The compound 1 along with kaempferol 3-O-glucuronide (compound 2) and quercetin 3-O-rhamnoside (compound 3) isolated from the same source were quantified by validated HPTLC method. Antioxidant activity was determined by chemical means in terms of ABTS radical cation and DPPH radical scavenging activity. Compound 1 showed significant scavenging activity in both ABTS and DPPH assays as compared to standard BHA. In ABTS method IC50 values of compound 1 and standard BHA is found to be 58.90 ± 3.40 µg/mL and 28.70 ± 5.20 µg/mL respectively while in DPPH assay IC50 values of Compound 1 and standard BHA is 47.20 ± 4.90 µg/mL and 34.50 ± 6.20 µg/mL respectively. Antidiabetic effect was studied through α-amylase and α-glucosidase inhibitory activity. The mechanistic approach through molecular modelling also support the strong binding sites of compound 1 which showed significant α-amylase and α-glucosidase inhibitory activities with IC50 values 128.34 ± 12.30 and 89.20 ± 9.20 µg/mL respectively as compared to acarbose 64.20 ± 5.60 and 52.40 ± 4.60 µg/mL respectively. The results of validated RP-HPTLC analyses revealed the concentration of compound 1 found to be 16.39 µg/mg and for compound 2 and compound 3 as 3.92 and 14.98 µg/mg of dried extract, respectively.

Theoretical Coupling and Stability of Boronic Acid Adducts with Catecholamines

Background: Catecholamines combined with boric/boronic acids are attractive chemical agents in drug design because some of their adducts have shown interesting biological activity. Scant information exists about their stability. Objective: The aim of the present theoretical study was to explore the role of boron in molecules that combine catecholamines and boric/boronic acids, with a particular interest in examining stability. Method: The methodology was based on the US GAMESS program using DFT with the B3LYP exchange-correlation functional and the 6-31G (d,p) split-valence basis set. Results: According to the current findings, the boron-containing compounds (BCCs) exhibit weaker bonding to the hydroxyls on the ethylamine moiety than to those in the aromatic ring. The strongest binding site of a hydroxyl group was often found to be in meta-position (relative to ethylamine moiety) for boron-free compounds and in para-position for BCCs. Nonetheless, the methyl substituent in the amino group was able to induce changes in this pattern. We analyzed feasible boronsubstituted structures and assessed the relative strength of the respective C-B bonds, which allowed for the identification of the favorable points for reaction and stability. Conclusion: It is feasible to form adducts by bonding on the amine and catechol sides of catecholamines. The presence of boron stabilizes the adducts in para-position. Since some of these BCCs are promising therapeutic agents, understanding the mechanisms of reaction is relevant for drug design.

Microporous Metal-Organic Framework with Dual Functionalities for Efficient Separation of Acetylene from Light Hydrocarbon Mixtures.

Separating acetylene from light hydrocarbon mixtures like ethylene is a very important process for downstream industrial applications. Herein, we report a new MOF [CuL2(SiF6)] (UTSA-220, L = (1E,2E)-1,2-bis(pyridin-4-ylmethylene)hydrazine) with dual functionalities featuring optimal pore size with strong binding sites for acetylene. UTSA-220 exhibits apparently higher uptake capacity for C2H2 than those for other light hydrocarbons. The potential of this material for trace C2H2 removal from C2H4 has also been demonstrated by a dynamic breakthrough experiment performed with C2H2/C2H4 (1/99 v/v) under simulated industrial conditions. According to the dispersion-corrected density functional theory (DFT-D) simulation, SiF6 2- and azine moieties serve as preferential binding sites for C2H2, indicating the feasibility of the dual functionalities incorporated in UTSA-220 for adsorbent-based C2H2 separations.

Silicon increases the phosphorus availability of Arctic soils

Phosphorus availability in soils is an important parameter influencing primary production in terrestrial ecosystems. Phosphorus limitation exists in many soils since a high proportion of soil phosphorus is stored in unavailable forms for plants, such as bound to iron minerals or stabilized organic matter. This is in spite of soils having a high amount of total soil phosphorus. The feasibility of silicon to mobilize phosphorus from strong binding sites of iron minerals has been shown for marine sediments but is less well studied in soils. Here we tested the effect of silicon on phosphorus mobilization for 143 Artic soils (representing contrasting soil characteristics), which have not been affected by agriculture or other anthropogenic management practices. In agreement with marine studies, silicon availabilities were significantly positive correlated to phosphorus mobilization in these soils. Laboratory experiments confirmed that silicon addition significantly increases phosphorus mobilization, by mobilizing Fe(II)-P phases from mineral surfaces. Silicon addition increased also soil respiration in phosphorus deficient soils. We conclude that silicon is a key component regulating mobilization of phosphorous in Arctic soils, suggesting that this may also be important for sustainable management of phosphorus availability in soils in general.