Arsenic (III) Methyltransferase

Overview

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Key numbers

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• Table 1. Sequences for the peptide fragments of hAS3MT analyzed by MALDI-TOF-MS.
• Table 2. Sequences for the peptide fragments of reduced hAS3MT analyzed by MALDI-TOF-MS.
• Table 3. Sequences for Cys32-Cys250 peptide fragments at 3451.17 (m/z) analyzed by MALDI-TOF-MS/MS.
• onto a 12% non-reducing sodium dodecyl sulfate-polyacryl amide hAS3MT-catalyzed the iAs3+ methylation in TCEP, GSH, DTT,
• acetate buffer (pH 6.0) and incubated in 5% trypsin buffer hAS3MT with 0.7 mM TCEP, 7.0 mM GSH, 1.5 mM DTT,
• 5 min in 60% acetonitrile and 0.1% (v/v) trifluoroacetic (16,32). analyzed by MADLDI-TOF-MS (15).
• solution containing 90% ACN and 0.1% TFA) was applied to the to 340 nm, and the emission wavelength (Em) was recorded from
• Table 4. Sequences for the IA-modified peptide fragments of Cys32 and Cys250 after hAS3MT-catalyzed the iAs3+ methylation.
• ppm 2215.54 141.05 146.03 272.26 57.44 278.60 Two disulfide bonds are detected in hAS3MT
• MALDI-TOF-MS (Figure 1a and Table 1). When hAS3MT was
• ure 2a). Meanwhile, the peak corresponding to Cys368 and (Figure 4d). In summary, the Cys250-Cys32 pair of hAS3MT was
• Cys206 (IA-modified) were detected (Figure 3a and Table 4). VIGDCRFVSATFR at 246–258. Because the disulfide bond of
• cleaved in the iAs3+ methylation. TOF-MS/MS (Figure 5e and Table 5). Fragment peaks corre-
• ppm 2176.82 2111.00 98.99 236.86 149.93 166.98 167.66 63.07 217.08 Cys250 mutation favors AdoMet binding to hAS3MT
• Table 5. Sequences for the AdoHcy-Cys250 peptide fragments at 1855.13 (m/z) analyzed by MALDI-TOF-MS/MS.
• ppm 184.24 248.64 dramatically (Figure 8a). We found that the catalytic activity of
• Table 6. Thermodynamic parameters for the binding of AdoMet to hAS3MT/C250S.
• exposed Cys157 and Cys207 serve as iAs3+ binding sites to and GSH. Meanwhile, Cys61 moves toward Cys156 and Cys206,

Methods (brief)

• flight-mass spectrometry (MALDI-TOF-MS) to analyze Cys residues in recombinant human arsenic (III) methyltransferase
• formed after iAs3+ was methylated to dimethylarsinous acid (DMA3+). In this work, we clarified both the functional roles of
• methylation. In this pathway, the reductant increased the number larsonous acid (MMA3+) to dimethylarsinous acid (DMA3+)
• catalysis of mouse AS3MT and CmArsM correspond to Cys206, coupled plasma (HPLC-ICP)-MS showed that the methylation of
• Sample preparation for MALDI-TOF-MS determination of Cys residues. Reduced hAS3MT and C360S
• alkylation, samples were washed twice with 50 mM ammonium Cys, and AdoMet on hAS3MT were studied by incubating
• Samples were lyophilized and stored at 280uC for mass
• spectrometry analysis. All buffers used in sample preparation were Fluorescence spectroscopy
• Before mass analysis, lyophilized samples were dissolved in fluorescence spectrometer (SLM Co., USA). At room temperature,
• same spot and left to dry for 2 min. Mass spectrometry was 230 nm to 500 nm. Fluorescence quenching spectra of C250S and
• Arsenicals were analyzed by HPLC-ICP-MS (PRP X-100,
• recovery systems were oxidized by H2O2 and analyzed by HPLC-
• ICP-MS (17,34). Meanwhile, adding of TCEP and DTT induced
• buried intemally, the in gel IA-modification and trypsin digestion
• iments. HPLC-ICP-MS was used to detect the trivalent arsenic
• sinic acid (DMA5+) and inorganic pentavalent arsenic (iAs5+) were
• the TCEP recovery system, the yield of DMA5+increased
• (18–21). Therefore, the cleavage of Cys250-Cys32 induced methylated to DMA3+ (17). Cys61 leaves away from Cys156 and

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
• Nickel

Verification notes

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Update history

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