Quantifying arsenic-binding

Overview

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Key numbers

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• to a wide range of environmental conditions. Evolutionary analyses had little changes (< 8%) even at the molar ratio of ArsR to
• less than 4% protein release after 60 h at 25◦ C (Figure 2D).
• Solid-phase arsenic absorbents (S-RpArsR2) were prepared as described in Materials and methods. Data are mean ± SD (n = 3 biological replicates).
• morphology with a size range of 0.54–1.23 µm (average: 0.81 µm), exhibiting the same binding capacity for As(III). Under equilibrium
• successful functionalization with RpArsR2. In the presence of f mean the binding and the free. Due to (S)t = n(S), (S)b = (M)b ,
• over a wide pH range (3.0–11.0), with optimal performance
• of both models were plotted as ln(Qe –Qt ) versus t (Supplementary and intercept values (Table 2). S-RpArsR2 variants (S1–S4)
• summarized in Table 1. The adsorption behavior of S-RpArsR2 was a 1:1 stoichiometry between As(III) and RpArsR2, and scaled
• that S-RpArsR2 significantly enhances both the rate and capacity binding aÿnity remains consistent across variants (RSD = 4.13%);
• completely removed 100µg/L As(III) from solution, while S alone strategy was demonstrated, as repeated immobilization (S4)
• removed less than 60%, highlighting the eectiveness of RpArsR- increased protein loading and enhanced As(III) adsorption capacity
• functionalized biosilica in arsenic adsorption. by 18.2% compared to single-step deposition (S3), despite a
• TABLE 1 Kinetic parameters of As(III) adsorption.
• once in the case of S3, and twice for S4. Data are mean ± SD (n = 3 biological replicates). Statistical significance determined by one-way ANOVA
• TABLE 2 The affinity constant (KA ) and binding site numbers (n) of S-RpArsR2.
• P + As(III) ←→ P − As(III) (5) 3%. This consistency indicates that immobilization did not alter
• 1 (R)b Table 3) was in excellent agreement with that obtained via
• KD1 (R)f )(AsIII)f ) independent fluorescence quenching (1.39 × 105 M, n = 1.07)
• (Supplementary Figure 5 and Supplementary Table 4), supporting
• of (R)f/(R)b versus vs. (P)f/(P)b for BSA, as a negative control to confirm specificity and validate the analytic method. Data are mean ± SD (n = 3
• shown in y-axis, which represents the ratio of As adsorption in the presence of heavy metals to that in metal-free controls (normalized as 100%). It
• reflects the percentage of retained binding capacity under interference conditions. A red horizontal line marks the 95% retention threshold. As(III)
• and methods. Data are mean ± SD (n = 3 biological replicates). Statistical significance determined by one-way ANOVA with LSD post-hoc test
• 2015; Ke et al., 2018), and the presence of nine phylogenetically and binding site density (n) for each variant (Table 3).
• TABLE 3 The affinity constant (KA ) and binding site numbers (n) of nine S-RpArsR complexes toward As(III).
• other RpArsRs showed lower site occupancy (n = 1.671 – to the exceptional arsenic resistance observed in CGA009.
• significant 21.3 ± 2.1% decrease in As(III) adsorption under metal
• interference (P < 0.05, n = 3). In contrast, eight of the nine
• S-RpArsR conjugates retained over 95% of their original As(III)
• showed a slightly greater reduction (5.5%), which aligns with its
• line in Figure 6B denotes the 95% retention threshold, indicating
• the highest As(III) aÿnity (Table 3). RpArsR2, which contains
• counts, displayed markedly dierent K A values (Table 3), implying we selected three S-RpArsR variants: S-RpArsR2, S-RpArsR3, and
• specific residue arrangements. These findings suggest that ArsR- hydroponic assays with Amaranthus tricolor. After 4-day exposure
• (biosilica spheres + 2.67 µM As(III)). Data are mean ± SD (n = 3 biological replicates). Statistical significance determined by one-way ANOVA with LSD post-hoc test. Dierent letters indicate
• µg/L As(III) for 4 days, as shown in Table 4, S-RpArsR treatments high As(III) uptake under competitive conditions. However,
• a 1,000 bootstraps. The amino acid sequences of nine RpArsRs was assessed by 12% sodium dodecyl sulfate polyacrylamide gel
• in Supplementary Table 1. system, which enables specific and covalent self-assembly.
• of biosilica spheres for 10 min in a 0.1 M PBS buer 100% adsorption capacity), with interference eects calculated as
• washed three times with deionized water, and dried overnight tricolor (fresh weight 1.96 ± 0.24 g) were soaked in 0.1%
• was incubated with 1.00 g/L of or 100 µg/L of As(III) (1.33 S-RpArsR8), and (6) 0.1 g/L biosilica spheres (S) as a control. Plants

Methods (brief)

• homologs have evolved distinct metal-binding motifs with variable HPLC-ICP-MS can measure As(III)-metallothionein coordination
• squares) versus free protein samples (red circles). (B1) Scatchard-style plots of (R)f /(R)b versus vs. (P)f /(P)b for S-RpArsR2. (B2) Scatchard-style plots
• Materials and methods collected for subsequent experiments. The fusion protein of
• resulting biosilica spheres (S) were collected by centrifugation at
• complexes were collected by centrifugation at 12,000 rpm
• in this study refer to samples prepared through a single To evaluate the selectivity of the S-RpArsR for As(III)
• characterization, S-RpArsR2 samples were treated with arsenic, using Amaranthus tricolor. The roots of healthy plant Amaranthus

Implications

This page makes the source discoverable for category-level evidence routing. Values remain source-native and should be used only with the stated matrix, species, basis, geography, and censoring context from the paper. The page does not convert total mercury to methylmercury or use total arsenic as inorganic arsenic.

Wiki pages this source may touch

• Fish — marine, non-predatory (sardines, anchovies, salmon, cod)
• Arsenic

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Update history

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