Disclosing the Preferential Mercury Chelation by SeCys

Overview

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Key numbers

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• stable linear Cys-Hg-Cys complex with the stability constant in the range of 1015-1042.8 The
• AVP (98% HPLC purity) was purchased from Eurogenetec . (Se-Se)-AVP (97% HPLC purity) was
• synthesized as previously described37,38 and (S-Se)-AVP (95% HPLC purity) was synthesized as
• Novabiochem was ≥ 99%.
• was acidified with HCl 37% to favor the precipitation of the product (cool in an ice bath). The
• HPLC as outlined below. Pure peptide was lyophilized recovering 50 mg (42.4% Yield) and
• carried out with acetic acid and ammonia commercial solutions (35% NH3). For the incubation
• dissolving salts in ultrapure water (0.1%HCl). For the pre-reduction of peptides, aliquots of their
• peptide concentration of 6 μM, using 2 mM ammonium acetate pH 7, 5 % (v/v) of ACN and 0.1 %
• Fisher Scientific). The mobile phases were A, H2O, and B, ACN, both with 0.1% FA. The flow
• the gradient from 5% to 95% of B over 6.5 min. An injection volume of 10 μL was used.
• and incubation times (from 30 min to 18 h) leading to several metal-peptide adducts (Table 1 and
• Table1. AVP peptides and their Hg adducts identified by mass spectrometry after incubation of the peptides with
• of these peptides in the reaction medium as follows: 51  1.6 % of 3 (bis-metallated adduct), 45 
• 1.7 % of 1 (unreacted peptide), 4.0  0.2 % of 2 (Hg-bridged peptide), these standard deviation
• of DTT during 30 min. (a) ICP-MS/MS detection: Se (blue line 96Se ICP intensity) and Hg (orange line 202Hg ICP
• (17 %) after 18 h incubation with 3 equiv of CH3HgCl.
• of 1 equiv of CH3HgCl: In this reaction medium, 34 % of the peptide still remained unreacted while
• the bis-metallated adduct 3 was largely formed (44 %) together with the Hg-bridged form 2 (22
• %). At any reaction time, when the excess of CH3HgCl increased, the starting peptide reacted
• formation of the Hg-bridged peptide 2 (96, 100 and 99 % with 3 equiv of CH3HgCl after 30 min,
• the mono- 4 and bis-metallated 3 adducts (29, 31 and 33 %, respectively). Like in the case of (Se-
• form of Hg-peptide adduct (65, 80 and 86 % with 3 equiv of CH3HgCl after 30 min, 3 h and 18 h
• time to be almost more totally metallated: 98 % at 18 h of incubation with 3 equiv of HgCl2.
• (S-Se)-AVP, as well as AVP, showed high conversion to the Hg-bridged adduct (above 78 %) at
• % of unreacted and Hg-bridged peptides are reported as function of HgCl2 excess at the different reaction time.
• CH3HgCl was able to metallate 83, 100 and 97 % of AVP, (Se-Se)-AVP and (S-Se)-AVP,
• 99, 98 and 91 %, respectively. HgCl2 did not favour its reaction with the Se peptide over the S
• Se)- and (S-Se)-AVP into the corresponding Hg-bridged species (95 and 93 %, respectively), the

Methods (brief)

• Selenocysteine, mercury, electrospray mass spectrometry, selenopeptide, mercury chelation.
• Hg-Cys) was evidenced in multi-cysteinyl peptides by mass spectrometry (MS) 12 and in several
• ultra-high resolution mass spectrometry (ESI-MS) the competitive reactivity of a model disulfide
• AVP (98% HPLC purity) was purchased from Eurogenetec . (Se-Se)-AVP (97% HPLC purity) was
• synthesized as previously described37,38 and (S-Se)-AVP (95% HPLC purity) was synthesized as
• as received without further purification. As example, the HPLC purity of Fmoc-Gly from
• HPLC as outlined below. Pure peptide was lyophilized recovering 50 mg (42.4% Yield) and
• Preparative HPLC was carried out on a LC8 Shimadzu HPLC system (Shimadzu Corporation,
• Purity of products was assessed using analytical HPLC (Agilent), column: C18-Phenomenex eluted
• dissolving the samples in ultrapure water. Ammonium acetate buffer solution (2 mM, pH 7.0) was
• After the incubation, all mercury (II) incubated solutions were sampled and diluted to a final
• Separation and identification of our samples was performed by LC-ESI MS. Liquid
• chromatography separations were performed using Dionex ultimate 3000 series UHPLC (Thermo
• rate used in all LC-MS experiments was 1 mL·min-1, and sample elution was performed by using
• methodology, the Dionex ultimate 3000 series UHPLC pump was coupled to a NexION 5000 ICP
• nebulizer of the multiquadrupole ICP MS instrument, which allowed us to work in MS/MS mode.
• On the base of the comparison of the ICP and ESI detection modes for the CH 3HgCl induced
• extrapolation. Indeed, direct ICP-MS evaluation could not be performed directly for the reactivity

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, predatory (tuna, swordfish, shark, king mackerel)
• Mercury
• Mercury
• Aluminum
• Tin

Verification notes

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Update history

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