Kinetics of the exchange reaction catalyzed by 2-amino-3-ketobutyrate CoA ligase

2-Amino-3-ketobutyrate CoA ligase (KBL) of Escherichia coli is a member of the α-oxoamine synthase family; it catalyzes the condensation reaction between glycine and acetyl CoA to yield 2-amino-3-ketobutyrate.We have previously shown that KBL catalyzes the exchange of pro-R hydrogen of glycine with protons in the medium; however, the kinetics of this reaction has never been determined. In this study, we calculated the kinetic parameters of this exchange reaction by using different concentrations of [2RS- ³H₂: 2-¹⁴C] glycine. The rate of the exchange reaction was determined by measuring the ³H/¹⁴C ratio in recovered [2S- ³H: 2-¹⁴C]glycine. The Lineweaver-Burk plot showed that K _m and k _cat of this reaction were 3.8 × 10^-3 M and 0.22 S^-1, respectively. On the other hand, K _m and k _cat values of the overall KBL-mediated catalysis were correspondingly 1.23 × 10^-2M and 1.19 S^-1. Thus, the rate of the exchange reaction was almost five times lower than that of overall KBL catalysis.     

Analysis of applicability of triplet-state emission of molecular hydrogen for spectral diagnostics of a DC discharge

The applicability of emission of the N ³Λ_σ triplet states of molecular hydrogen for spectral diagnostics of the positive column of a dc glow discharge in hydrogen at translational gas temperatures of 360–600 K, specific absorbed powers of 0.8–4.25 W/cm, gas pressures of p = 0.3–15.0 Torr, reduced fields of E/N = 30–130 Td, and electron densities of n _e = 4.0 × 10⁹–6.5 × 10¹⁰ cm^–3 is analyzed by using an advanced level-based semi-empirical collisional?radiative model. It is found that secondary processes make the main contribution to the population and decay of the N ³Λ_σ = a ³Σ⁺ _g , c ³Π _u , g ³Σ⁺ _g , h ³Σ⁺ _g , and i ³Π _g triplet states. The dipole-allowed transitions e ³Σ⁺ _g → a ³Σ⁺ _g , f ³Σ⁺ _g → a ³Σ⁺ _g , g ³Σ⁺ _g and k ³Π _u → a ³Σ⁺ _g can be used for spectral diagnostics of a dc discharge within a simplified coronal model.     

Purification and Characterization of a Novel (<Emphasis Type="Italic">R</Emphasis>)-1-Phenylethanol Dehydrogenase from <Emphasis Type="Italic">Lysinibacillus</Emphasis> sp. NUST506

A novel (R)-1-phenylethanol dehydrogenase was successfully purified from Lysinibacillus sp. NUST506 by preparative polyacrylamide gel electrophoresis. The enzyme is a NAD+-dependent oxidoreductase. The molecular weight of the (R)-1-phenylethanol dehydrogenase measured by SDS-PAGE was about 28 kDa. Furthermore, the optimal reaction conditions for the oxidative reaction were 70°C and pH 9.5 and for the reductive reaction were 65°C and pH 6.5. Under the optimal conditions, the K_M and k_cat values with (R)-1-phenylethanol as a substrate were found to be 0.78 mM and 123 s^–1 and with acetophenone they were 0.56 mM and 125 s^–1, respectively. The (R)-1-phenylethanol dehydrogenase became more stable at pH 9.5 in comparison with pH 5.0 and high stability was noticed at 4 and 37°C. Properties of the enzyme place it as a promising candidate for industrial applications.     

Theoretical investigation on exciton-dissociation and charge-recombination processes of PC<Subscript>61</Subscript>BM-PTDPPSe interface

Designing and synthesizing novel electron-donor polymers with the high photovoltaic performances has remained a major challenge and hot issue in organic electronics. In this work, the exciton-dissociation (k _dis ) and charge-recombination (k _rec ) rates for the PC₆₁BM-PTDPPSe system as a promising polymer-based solar cell candidate have been theoretically investigated by means of density functional theory (DFT) calculations coupled with the non-adiabatic Marcus charge transfer model. Moreover, a series of regression analysis has been carried out to explore the rational structure–property relationship. Results reveal that the PC₆₁BM-PTDPPSe system possesses the large open-circuit voltage (0.77 V), middle-sized exiton binding energy (0.457 eV), and relatively small reorganization energies in exciton-dissociation (0.273 eV) and charge-recombination (0.530 eV) processes. With the Marcus model, the k _dis , k _rec , and the radiative decay rate (k _s ), are estimated to be 3.167×10¹¹ s^?1, 3.767×10¹⁰ s^?1, and 7.930×10⁸ s^?1 respectively in the PC₆₁BM-PTDPPSe interface. Comparably, the k _dis is as 1～3 orders of magnitude larger than the k _rec and the k _s , which indicates a fast and efficient photoinduced exciton-dissociation process in the PC₆₁BM-PTDPPSe interface.

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Graphical Abstract PTDPPSe is predicted to be a promising electron donor polymer, and the PC₆₁BM-PTDPPSe system is worthy of further device research by experiments.

     

Short-term effects of crop rotation,residue management,and soil water on carbon mineralization in a tropical cropping system

The purpose of this study was to investigate the short-term effects of maize (Zea mays)-fallow rotation, residue management, and soil water on carbon mineralization in a tropical cropping system in Ghana. After 15 months of the trial, maize–legume rotation treatments had significantly (P?C ₀ (μg CO₂–C g^?1) than maize–elephant grass (Pennisetum purpureum) rotations. The C ₀ for maize–grass rotation treatments was significantly related to the biomass input (r?=?0.95; P?=?0.05), but that for the maize–legume rotation was not. The soil carbon mineralization rate constant, k (per day), was also significantly related to the rotation treatments (P?k values for maize–grass and maize–legume rotation treatments were 0.025 and 0.036 day^?1 respectively. The initial carbon mineralization rate, m ₀ (μg CO₂–C g^?1 day ^?1), was significantly (P?θ. The m ₀ ranged from 3.88 to 18.67 and from 2.30 to 15.35 μg CO₂–C g^?1 day^?1 for maize–legume and maize–grass rotation treatments, respectively, when the soil water varied from 28% to 95% field capacity (FC). A simple soil water content (θ)-based factor, f _w, formulated as: \(f_{\text{w}} = \left[ {\frac{{\theta - \theta _{\text{d}} }}{{\theta _{{\text{FC}}} - \theta _{\text{d}} }}} \right]\), where θ _d and θ _FC were the air-dry and field capacity soil water content, respectively, adequately described the variation of the m ₀ with respect to soil water (R ²?=?0.91; RMSE?=?1.6). Such a simple relationship could be useful for SOC modeling under variable soil water conditions.     

Analysis of the interaction of gallic acid and myoglobin by UV-vis absorption spectroscopy

UV-vis absorption spectroscopy has been used to analyze the interaction of myoglobin (Мb) and gallic acid (GA). The binding constants (4.38 × 10⁴ M^–1 at 298.15 K and 0.42 × 10⁴ М^–1 at 308.15K), the number of binding sites (h = 1.0), and the thermodynamic parameters of binding (ΔH, ΔS, and ΔG) have been determined. Hydrogen bonds have been shown to play a major role in the stabilization of the GA–Мb complexes. GA binding led to slight changes in the electronic state of the heme ring of the protein.     

The nitrite reductase activity of horse heart carboxymethylated-cytochrome <Emphasis Type="Italic">c</Emphasis> is modulated by cardiolipin

Horse heart carboxymethylated cytc (CM-cytc) displays myoglobin-like properties. Here, the effect of cardiolipin (CL) liposomes on the nitrite reductase activity of ferrous CM-cytc [CM-cytc-Fe(II)], in the presence of sodium dithionite, is reported between pH 5.5 and 7.6, at 20.0 °C. Cytc-Fe(II) displays a very low value of the apparent second-order rate constant for the NO₂ ^?-mediated conversion of cytc-Fe(II) to cytc-Fe(II)-NO [k _on = (7.3 ± 0.7) × 10^?2 M^?1 s^?1; at pH 7.4], whereas the value of k _on for NO₂ ^? reduction by CM-cytc-Fe(II) is 1.1 ± 0.2 M^?1 s^?1 (at pH 7.4). CL facilitates the NO₂ ^?-mediated nitrosylation of CM-cytc-Fe(II) in a dose-dependent manner, the value of k _on for the NO₂ ^?-mediated conversion of CL–CM-cytc-Fe(II) to CL–CM-cytc-Fe(II)-NO (5.6 ± 0.6 M^?1 s^?1; at pH 7.4) being slightly higher than that for the NO₂ ^?-mediated conversion of CL–cytc-Fe(II) to CL–cytc-Fe(II)-NO (2.6 ± 0.3 M^?1 s^?1; at pH 7.4). The apparent affinity of CL for CM-cytc-Fe(II) is essentially pH independent, the average value of B being (1.3 ± 0.3) × 10^?6 M. In the absence and presence of CL liposomes, the nitrite reductase activity of CM-cytc-Fe(II) increases linearly on lowering pH and the values of the slope of the linear fittings of Log k _on versus pH are ?1.05 ± 0.07 and ?1.03 ± 0.03, respectively, reflecting the involvement of one proton for the formation of the transient ferric form, NO, and OH^?. These results indicate that Met80 carboxymethylation and CL binding cooperate in the stabilization of the highly reactive heme-Fe atom of CL–CM-cytc.     

Perchlorate reduction by hydrogen autotrophic bacteria and microbial community analysis using high-throughput sequencing

Hydrogen autotrophic reduction of perchlorate have advantages of high removal efficiency and harmless to drinking water. But so far the reported information about the microbial community structure was comparatively limited, changes in the biodiversity and the dominant bacteria during acclimation process required detailed study. In this study, perchlorate-reducing hydrogen autotrophic bacteria were acclimated by hydrogen aeration from activated sludge. For the first time, high-throughput sequencing was applied to analyze changes in biodiversity and the dominant bacteria during acclimation process. The Michaelis–Menten model described the perchlorate reduction kinetics well. Model parameters q _max and K _s were 2.521–3.245 (mg ClO₄ ^?/gVSS h) and 5.44–8.23 (mg/l), respectively. Microbial perchlorate reduction occurred across at pH range 5.0–11.0; removal was highest at pH 9.0. The enriched mixed bacteria could use perchlorate, nitrate and sulfate as electron accepter, and the sequence of preference was: NO₃ ^? > ClO₄ ^? > SO₄ ^2?. Compared to the feed culture, biodiversity decreased greatly during acclimation process, the microbial community structure gradually stabilized after 9 acclimation cycles. The Thauera genus related to Rhodocyclales was the dominated perchlorate reducing bacteria (PRB) in the mixed culture.     

Reaction of turbulence at the edge and in the center of the plasma column to pulsed impurity injection caused by the sputtering of the wall coating in L-2M stellarator

Impurity injection into plasma caused by the sputtering of the wall coating in the L-2M stellarator during auxiliary electron cyclotron resonance heating leads to a change in the level of plasma density fluctuations with frequencies above 0.25 MHz: suppression of long-wavelength (k _⊥ = 2 cm^–1) density fluctuations in the edge plasma, intensification of short-wavelength (k _⊥ = 30 cm^–1) and long-wavelength (k _⊥ = 1 cm^–1) fluctuations at the midradius of the plasma column, and intensification of short-wavelength fluctuations (k _⊥ = 20 cm^–1) in the plasma center (including the gyroresonance region). At the same time, the level of fluctuations with frequencies below 0.25 MHz remains unchanged. In the edge plasma, a decrease in the plasma potential and suppression of its fluctuations is observed during impurity injection, which also causes an increase in MHD activity.     

Acetaldehyde kinetics of enological yeast during alcoholic fermentation in grape must

Acetaldehyde strongly binds to the wine preservative SO₂ and, on average, causes 50–70 mg l^?1 of bound SO₂ in red and white wines, respectively. Therefore, a reduction of bound and total SO₂ concentrations necessitates knowledge of the factors that affect final acetaldehyde concentrations in wines. This study provides a comprehensive analysis of the acetaldehyde production and degradation kinetics of 26 yeast strains of oenological relevance during alcoholic fermentation in must under controlled anaerobic conditions. Saccharomyces cerevisiae and non-Saccharomyces strains displayed similar metabolic kinetics where acetaldehyde reached an initial peak value at the beginning of fermentations followed by partial reutilization. Quantitatively, the range of values obtained for non-Saccharomyces strains greatly exceeded the variability among the S. cerevisiae strains tested. Non-Saccharomyces strains of the species C. vini, H. anomala, H. uvarum, and M. pulcherrima led to low acetaldehyde residues (<10 mg l^?1), while C. stellata, Z. bailii, and, especially, a S. pombe strain led to large residues (24–48 mg l^?1). Acetaldehyde residues in S. cerevisiae cultures were intermediate and less dispersed (14–34 mg l^?1). Addition of SO₂ to Chardonnay must triggered significant increases in acetaldehyde formation and residual acetaldehyde. On average, 0.33 mg of residual acetaldehyde remained per mg of SO₂ added to must, corresponding to an increase of 0.47 mg of bound SO₂ per mg of SO₂ added. This research demonstrates that certain non-Saccharomyces strains display acetaldehyde kinetics that would be suitable to reduce residual acetaldehyde, and hence, bound-SO₂ levels in grape wines. The acetaldehyde formation potential may be included as strain selection argument in view of reducing preservative SO₂ concentrations.     

OH Radicals in Radiation Sensitization

CELLS can be sensitized to ionizing radiation by chemical compounds and this offers opportunity for investigating the mechanisms intermediate between energy absorption and expression of biological effect. Concentration dependence seems to be an important factor for the effectiveness of a radiation sensitizer. The inactivation constant k for X-irradiated suspensions of Bacillus megaterium spores shows a peak at 3 × 10^?3 M diacetyl (CH₃COCOCH₃) concentration¹. Although the mechanism of this effect is unknown, certain free radical reactions have been suggested^2–4. The decrease of k with increasing sensitizer concentration, envisaged as a protective action, indicates a competitive reaction in which the species contributing to the lethality are removed.     

Feruloyl esterase from <Emphasis Type="Italic">Alternaria tenuissima</Emphasis> that hydrolyses lignocellulosic material to release hydroxycinnamic acids

An extracellular feruloyl esterase from the culture filtrates of the isolated fungus Alternaria tenuissima was successfully purified to apparent homogeneity by anion-exchange and size-exclusion chromatography. Peptide fragments of purified enzyme (designated as AltFAE; molecular weight of 30.3 kDa determined by SDS-PAGE) were identified by mass spectrometry using a NanoLC-ESI-MS/MS system. Michaelis-Menten constants (K_M) and catalytic efficiencies (k_cat/K_M) were determined for typical substrates of feruloyl esterase, and the lowest K_M of 50.6 μM (i.e., the highest affinity) and the highest k_cat/K_M (3.1 × 10⁵ s^—1 M^–1) were observed for methyl ^p-coumarate and methyl ferulate, respectively. Not least, AltFAE catalyzed conversion of lignocellulosic material (e.g. wood meal) to release hydroxycinnamic products, i.e. ferulic- and ^p-coumaric acids.     

Theoretical study of the H + HCN → H + HNC process

We present a theoretical study on the detailed mechanism and kinetics of the H+HCN →H+HNC process. The potential energy surface was calculated at the complete basis set quantum chemical method, CBS-QB3. The vibrational frequencies and geometries for four isomers (H₂CN, cis-HCNH, trans-HCNH, CNH₂), and seven saddle points (TSn where n = 1 ? 7) are very important and must be considered during the process of formation of the HNC in the reaction were calculated at the B3LYP/6-311G(2d,d,p) level, within CBS-QB3 method. Three different pathways (PW1, PW2, and PW3) were analyzed and the results from the potential energy surface calculations were used to solve the master equation. The results were employed to calculate the thermal rate constant and pathways branching ratio of the title reaction over the temperature range of 300 up to 3000 K. The rate constants for reaction H + HCN → H + HNC were fitted by the modified Arrhenius expressions. Our calculations indicate that the formation of the HNC preferentially occurs via formation of cis–HCNH, the fitted expression is k _{P W2}(T) = 9.98 × 10^?22 T ^2.41 exp(?7.62 kcal.mol^?1/R T) while the predicted overall rate constant k _{O v e r a l l} (T) = 9.45 × 10^?21 T ^2.15 exp(?8.56 kcal.mol^?1/R T) in cm ³ molecule ^?1 s ^?1.

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Graphical Abstract (a) Potential energy surface, (b) thermal rate constants as a function of temperature and (c) the branching ratios (%) of PW1, PW2, PW3 pathways involved in rm H + HCN → H + HNC process.

     

Physical Parameters of a Reactor-Stellarator with Small Ripples of the Helical Magnetic Field

The paper describes the calculation data on the physical parameters of a reactor-stellarator, where the nonuniformities of the helical field are smaller than the toroidal magnetic field nonuniformities: ε_h < ε_t. Unlike the previous studies, where the ion-component transport coefficients had the collision frequency dependence proportional to ν^1/2, this being equivalent to the ε_h > ε_t case, in the present calculations, these coefficients were assumed to be in proportion to the first power of the collision frequency, D_i ∝ ν for ν_eff < 2ω_E, and to D_i ∝ ν^?1 for the inverse inequality. Here, ω_E is the rotation frequency of plasma in the radial electric field. As before, the plasma electrons corresponded to the mode of D_e ∝ ν^?1. As initial parameters for numerical calculations, a reactor with R = 8 m, r_p = 2 m, and B₀ = 5 Т was taken. A numerical code was used to solve the set of equations that describes the plasma space?time behavior in the reactor-stellarator under the conditions of equal diffusion fluxes. The start of reactor operation in the mode of thermonuclear burning was provided by heating sources with a power of several tens of megawatts. Steady-state operating conditions of a self-sustained thermonuclear reaction were attained by maintaining the plasma density through DT fuel pellet injection into the plasma.     

Isolating and confirming the <Emphasis Type="Italic">MuDR</Emphasis>-inserted flanking sequences of maize

MuDR exhibits the highest transposition activity and insertional mutagenesis frequency in Mutator (Mu) family. If we isolate the MuDR-insertion-specific flanking sequences (MuDRFs), it will be crucial for using Mu element-mediated mutants. The MuDR-TAIL-PCR system was constructed and optimized using a combination of MuDR-TIR-nested specific primers and 12 arbitrary degenerate (AD) primers, modified reaction system and procedure and mutant DNA templates of 87 genotypes from M₂ or М_2:3 families created by crossing the W22::Mu line (active MuDR donor parent) from the UniformMu population with the Zong31 (Z31) line (recipient parent). Here 129 different MuDRFs were acquired by MuDR-TAIL-PCR, accounting for 86.60% of the total mutant-specific agarose gel bands. In addition, we confirmed the authenticity of the non-redundant flanking sequence amplifications. The amplified non-redundant flanking sequences accounted for 65.12% of the total MuDRFs, and 88.00% of the non-redundant MuDRFs were inserted inside the genes. These results show that the MuDR-TAIL-PCR system that we developed can be used for specifically isolating MuDRFs.     

A precise and consistent assay for major wall polymer features that distinctively determine biomass saccharification in transgenic rice by near-infrared spectroscopy

Background

The genetic modification of plant cell walls has been considered to reduce lignocellulose recalcitrance in bioenergy crops. As a result, it is important to develop a precise and rapid assay for the major wall polymer features that affect biomass saccharification in a large population of transgenic plants. In this study, we collected a total of 246 transgenic rice plants that, respectively, over-expressed and RNAi silenced 12 genes of the OsGH9 and OsGH10 family that are closely associated with cellulose and hemicellulose modification. We examined the wall polymer features and biomass saccharification among 246 transgenic plants and one wild-type plant. The samples presented a normal distribution applicable for statistical analysis and NIRS modeling.

Results

Among the 246 transgenic rice plants, we determined largely varied wall polymer features and the biomass enzymatic saccharification after alkali pretreatment in rice straws, particularly for the fermentable hexoses, ranging from 52.8 to 95.9%. Correlation analysis indicated that crystalline cellulose and lignin levels negatively affected the hexose and total sugar yields released from pretreatment and enzymatic hydrolysis in the transgenic rice plants, whereas the arabinose levels and arabinose substitution degree (reverse xylose/arabinose ratio) exhibited positive impacts on the hexose and total sugars yields. Notably, near-infrared spectroscopy (NIRS) was applied to obtain ten equations for predicting biomass enzymatic saccharification and seven equations for distinguishing major wall polymer features. Most of the equations exhibited high R ²/R ² _cv/R ² _ev and RPD values for a perfect prediction capacity.

Conclusions

Due to large generated populations of transgenic rice lines, this study has not only examined the key wall polymer features that distinctively affect biomass enzymatic saccharification in rice but has also established optimal NIRS models for a rapid and precise screening of major wall polymer features and lignocellulose saccharification in biomass samples. Importantly, this study has briefly explored the potential roles of a total of 12 OsGH9 and OsGH10 genes in cellulose and hemicellulose modification and cell wall remodeling in transgenic rice lines. Hence, it provides a strategy for genetic modification of plant cell walls by expressing the desired OsGH9 and OsGH10 genes that could greatly improve biomass enzymatic digestibility in rice.

     

Cloning and characterization of a novel amidase from <Emphasis Type="Italic">Paracoccus</Emphasis> sp. M-1, showing aryl acylamidase and acyl transferase activities

A novel amidase gene, designated pamh, was cloned from Paracoccus sp. M-1. Site-directed mutagenesis and bioinformatic analysis showed that the PamH protein belonged to the amidase signature enzyme family. PamH was expressed in Escherichia coli, purified, and characterized. The molecular mass of PamH was determined to be 52 kDa with an isoelectric point of 5.13. PamH displayed its highest enzymatic activity at 45°C and at pH 8.0 and was stable within a pH range of 5.0–10.0. The PamH enzyme exhibited amidase activity, aryl acylamidase activity, and acyl transferase activity, allowing it to function across a very broad substrate spectrum. PamH was highly active on aromatic and short-chain aliphatic amides (benzamide and propionamide), moderately active on amino acid amides, and possessed weak urease activity. Of the anilides examined, only propanil was a good substrate for PamH. For propanil, the k _cat and K _m were 2.8 s^?1 and 158 μM, respectively, and the catalytic efficiency value (k _cat/K _m) was 0.018 μM^?1 s^?1. In addition, PamH was able to catalyze the acyl transfer reaction to hydroxylamine for both amide and anilide substrates, including acetamide, propanil, and 4-nitroacetanilide; the highest reaction rate was shown with isobutyramide. These characteristics make PamH an excellent candidate for environmental remediation and an important enzyme for the biosynthesis of novel amides.     

Peroxidase activity of octaheme nitrite reductases from bacteria of the <Emphasis Type="Italic">Thioalkalivibrio</Emphasis> genus

Closely related penta- and octaheme nitrite reductases catalyze the reduction of nitrite, nitric oxide, and hydroxylamine to ammonium and of sulfite to sulfide. NrfA pentaheme nitrite reductase plays the key role in anaerobic nitrate respiration and the protection of bacterial cells from stresses caused by nitrogen oxides and hydrogen peroxide. Octaheme nitrite reductases from bacteria of the Thioalkalivibrio genus are less studied, and their function in the cell is unknown. In order to estimate the possible role of octaheme nitrite reductases in the cell resistance to oxidative stress, the peroxidase activity of the enzyme from T. nitratireducens (TvNiR) has been studied in detail. Comparative analysis of the active site structure of TvNiR and cytochrome c peroxidases has shown some common features, such as a five-coordinated catalytic heme and identical catalytic residues in active sites. A model of the possible productive binding of peroxide at the active site of TvNiR has been proposed. The peroxidase activity has been measured for TvNiR hexamers and trimers under different conditions (pH, buffers, the addition of CaCl₂ and EDTA). The maximum peroxidase activity of TvNiR with ABTS as a substrate (k _cat = 17 s^–1; k _cat/K _m = 855 mM^–1 s^–1) has been 100–300 times lower than the activity of natural peroxidases. The different activities of TvNiR trimers and hexamers indicate that the rate-limiting stage of the reaction is not the catalytic event at the active site but the electron transfer along the heme c electron-transport chain.     

Anomalous pinch in the T-11M tokamak in an enhanced-collisionality regime

The formation of a peaked bell-shaped profile of the electron density n _e (r) in the T-11M tokamak (B _t=1 T, R/a = 0.7/0.2 m, I _p = 100 kA, t _shot ≤ 300 ms, Li and C limiters) was observed in Li experiments carried out in the near-plateau collisionality regime (the collisionality parameter at one-half of the minor radius was v* ≥ 0.5) under the conditions of low hydrogen recycling and intense hydrogen influx from the plasma edge. It is well known that peaked n _e (r) profiles are observed in collisionless regimes at v* values as low as 10^?1–10^?2 or in impurity-contaminated discharges, in which this effect can be attributed to the impurity accumulation on the plasma column axis. Moreover, a bell-shaped n _e (r) profile in discharges with low n _e can result from the ionization of hydrogen atoms at the column axis, where they arrive from the plasma edge due to cascade charge-exchange. In quasi-steady lithium discharges in T-11M, however, peaked n _e (r) profiles were observed at a relatively high central electron density n _e (0) and relatively high collision frequency, such that the influence of impurities on the n _e (r) profile could be ignored (Z _eff = 1.1±0.1). To explain this effect, one has to assume that the pinching of hydrogen ions in T-11M is anomalous. The lower estimate of the observed pinch velocity is 4 ± 1 m/s, which is three to five times higher than the velocity of the neoclassical (Ware) pinch, characteristic of these conditions. The work is devoted to the experimental study of this effect.