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Metal ions and other elements play many different critical roles in all biological processes. They can be especially important in high concentrations for the functioning of organisms living in seawater. It is important to understand how much the concentrations of different trace elements in such organisms can be higher than in seawater. Some marine organisms capable of rapid recovery after different injuries are fascinating in this regard. Sea cucumbers Eupentacta fraudatrix can completely restore all organs and the whole body within several weeks after their division into two parts. Here, for the first time, a comparison of the content of different elements in seawater, sea cucumber, and its very stable multiprotein complex (2000 kDa) was performed using two-jet plasma atomic emission spectrometry. Among the 18 elements we found in sea cucumbers, seawater contained only six elements in detectable amounts, and their content decreased in the following order: Mg > Ca > B > Sr ≈ Si > Cr (0.13−930 µg/g of seawater). The content of these elements in sea cucumbers was higher compared with seawater (-fold): Ca (714) > Sr (459) > Cr (75) > Si (42)> B (12) > Mg (6.9). Only four of them had a higher concentration in the protein complex than in seawater (-fold): Si (120.0) > Cr (31.5) > Ca (9.1) > Sr (8.8). The contents of Mg and B were lower in the protein complex than in seawater. The content of elements additionally found in sea cucumbers decreased in the order (µg/g of powder) of P (1100) > Fe (47) > Mn (26) > Ba (15) > Zn (13) > Al (9.3) > Mo (2.8) > Cu (1.4) > Cd (0.3), and in the protein complex, in the order of P (290) > Zn (51) > Fe (23) > Al (14) ≈ Ni (13) > Cu (7.5) > Ba (2.5) ≈ Co (2.0) ≈ Mn (1.6) > Cd (0.7) >Ag (0.2). Thus, sea cucumbers accumulate various elements, including those contained in very low concentrations in seawater. The possible biological roles of these elements are discussed here.

In this paper, we have performed determination of the concentration of twenty elements in seven human organs (spleen, liver, kidney, muscle, heart, lungs, and brain) using two-jet plasma atomic emission spectrometry. The method allows multielemental analysis of solid samples without wet acid digestion. Before analysis, all human organs were first dried, ground to powders, and carbonized. The relative content of elements in each of the seven organs was very different depending on the donor. The average content of twenty elements in various organs varied in the following ranges ( μ g/g of dry weight): Ag (<0.02-0.2), Al (2.1-263), B (<0.5-2.5), Ca (323-1650), Cd (<0.1-114), Co (<0.2-1.0), Cr (<0.5-4.0), Cu (4.2-47), Fe (156-2900), Mg (603-1305), Mn (0.47-8.5), Mo (<0.2-4.9), Ni (<0.3-3.1), Pb (<0.3-1.9), Si (31.6-2390), Sn (<0.3-3.2), Sr (0.2-1.0), Ti (<2-31, mainly in lungs), and Zn (120-292). The concentration range of Ba in organs of five donors was <0.2-6.9 and 2.0-5600 for one donor with pneumoconiosis (baritosis). The maximum element contents were found, respectively, in the following organs: Al, B, Cr, Ni, Si, Sn, Sr, Ti (lungs), Fe (lungs and spleen), Mn (liver and kidney), Ag and Mo (liver), Ca (lungs and kidney), Cu (brain), Cd (kidney), Pb (brain), and Zn (liver, kidney, and muscle). The minimal content of elements was observed, respectively, in the following organs: Ag (all organs except liver), Ba (spleen, muscles, and brain), Ca and Mg (liver), Si (liver, muscle, and brain), Cd and Sr (heart and brain), Al, Cu, Fe, and Mn (muscle), and Zn (spleen and brain). The analysis of possible biological role and reasons for the increased content of some elements in the organs analyzed was carried out., Competing Interests: The authors declare no conflicts of interest., (Copyright © 2019 Natalia P. Zaksas et al.)

Background: Many biological processes are performed by different protein complexes. During the association of proteins and enzymes forming specific complexes, the latter can include ions of various metal ions, which may be important for their formation and biological function., Objective of the Studies: However, to date in the literature there are no data on metal ions that are part of any protein complexes., Methods: A very stable multiprotein complex (~1000±100 kDa) was separated from other proteins of nine samples of female milk by gel filtration on Sepharose 4B. The content of microelements in the stable multiprotein complex and milk was analyzed using two-jet plasma atomic emission spectrometry., Results: The content of different elements in milk on average decreased in the order: Ca>P>Mg>Al≥Zn≥Fe>Cu >B (0.76-3500 μ g/g of dry milk powder), while the content of some elements was very low (Sr>Mn>Cr>Ba>Pb>Ag>Ni>Cd, <0.03-0.5 μ g/g). The content of eight elements in stable multiprotein complex was 1.2-9.6-fold higher than in milk and increased in the order: Ca≈MgB (19.7)>Ag (28.7)>Ni (38)≥Sr (110)., Conclusions: The analysis of the relative content of sixteen elements in human milk and oligomeric complexes of proteins was performed for the first time. Data on the content of metals indicate that during the formation of protein which associates the increase in the content of metal ions bound with proteins of the complex can occur. Such metal ions can be important for the formation and biological function of protein complexes., Competing Interests: The authors declare no conflicts of interest.

The possibility of two-jet plasma atomic emission spectrometry for analysis of different plants using solid sample preparation and unified calibration samples was investigated. The certified reference materials of wheat, maize, rice, potato, grass mix, birch leaves, and Elodea canadensis were used for analysis. On the basis of the behavior of these plants in the plasma, they were divided into two groups: starch-containing materials (cereal and root crops) and leaves/grass. It was found that the previous sample carbonization should be used for analysis of starch-containing plants while leaves and grass could be analyzed by the direct technique. Carbonization was only applied for determining low concentrations of trace elements in leaves and grass. The calibration samples based on graphite powder and simple sample preparation, dilution of powdered sample with a spectroscopic buffer, were used for both direct analysis and analysis after carbonization. Such an approach allowed estimation of B, Ba, Be, Cd, Co, Cr, Cu, Ga, Fe, Mn, Ni, Pb, Si, Sr, V, and Zn in different plants. The limits of detection (LODs) provided by the direct technique were at the level of (µg·g -1 ): n × 0.1 for Cd, Cu, and Mn; n for B, Ba, Co, Cr, Fe, Ga, Ni, Pb, Sr, V, and Zn; n × 10 for Si. Carbonization allowed improving LODs of elements several times depending on the thermal stability and mineral composition of plants. The LODs of elements in plants obtained after carbonization are the following (µg·g -1 ): n × 0.01 for Be, Cd, Cu, and Mn; n × 0.1 for Co, Cr, Fe, Ga, Ni, Pb, Sr, V, Zn; and n for Si. The techniques suggested are fast, easily workable, and do not require harmful chemical reagents. In some cases, the influence of variable matrices and different element species on analytical signal of elements was not completely suppressed; the deviation of element concentrations from the true values was discussed.

The possibility of direct analysis of soils by two-jet plasma atomic emission spectrometry was investigated using certified reference materials of black earth, grey desert and red soils. It was shown that As, B, Cd, Cu, Hg, P, and V could be determined after a 2-fold, and Be, Co, Cr, Ga, Nb, Pb, and Zn-after a 10-fold dilution of the samples by a spectroscopic buffer using calibration samples based on graphite powder. The strongest matrix effects were revealed for red soil having the highest Al and Fe concentration, which led to the overstated concentrations of some elements. The overstating factor depended on analyte concentration and was no more than 2. A clear advantage of the suggested technique over existing methods is the simple sample preparation process, which requires no reagents except a spectroscopic buffer, and possibility of using the same calibration samples for analysis of different soils.

Cobalt is a transition metal and an essential trace element that is required for vitamin B₁₂ biosynthesis, enzyme activation, and so on but is toxic in high concentrations. It was shown that the content of different elements in the plasma of 2-month-old BALB/c mice (control group) decreased in the following order: Ca > Mg > Si > Fe > Zn > Cu ≥ Al ≥ B. The treatment of mice with CoCl₂ did not appreciably change the relative content of Ca, Cu, and Zn, but a significant increase in the content of B (2.3-fold), Mg (1.5-fold), Al and Fe (2.1-fold), and Si (3.4-fold) was found. The treatment of mice led to a 2.2-fold decrease in the concentration of the total blood protein and a 1.7 ± 0.2-fold decrease of total immunoglobulin Gs (IgGs). Deoxyribonuclease IgGs corresponding to mice treated (t-IgGs) and non-treated (nt-IgGs) with CoCl₂ contained intrinsically bound metal ions; these IgGs hydrolyzed DNA with very low activity but were not active in the presence of ethylenediaminetetraacetic acid or after Ab dialysis against ethylenediaminetetraacetic acid. The average RAs of deoxyribonuclease nt-IgGs increased after addition of external metal ions in the following order: Zn²⁺< Ca²⁺ < Cu²⁺ < Fe²⁺ < Mn²⁺ < Mg²⁺ < Co²⁺ < Ni²⁺. Interestingly, t-IgGs demonstrated lower activities than those for nt-IgGs either in the absence of external metal ions (2.7-fold) or in the presence of Cu²⁺ (9.5-fold) > Co²⁺ (5.6-fold) > Zn²⁺ (5.1-fold) > Mg²⁺ (4.1-fold) > Ca²⁺ (3.0-fold) > Fe²⁺ (1.3-fold). However, the RAs of t-IgGs were remarkably more active than nt-IgGs in the presence of best activators of t-IgGs Ni²⁺ (1.4-fold) and especially Mn²⁺ (2.2-fold). The data may be useful for an understanding of Co toxicity, its effect on the concentration of other metal ions, and a change of metal-dependent specificity of Abzs., (Copyright © 2012 John Wiley & Sons, Ltd.)

We present the first evidence that electrophoretically and immunologically homogeneous sIgAs purified from milk of healthy human mothers by chromatography on Protein A-Sepharose and FPLC gel filtration contain intrinsically bound metal ions (Ca  >  Mg ≥ Al > Fe approximately  Zn ≥ Ni ≥ Cu ≥ Mn), the removal of which by a dialysis against ethylenediamine tetraacetic acid (EDTA) leads to a significant decrease in the β-casein-hydrolyzing activity of these antibodies (Abs). An affinity chromatography of total sIgAs on benzamidine-Sepharose interacting with canonical serine proteases separates a small metalloprotease sIgA fraction (6.8 ± 2.4%) from the main part of these Abs with a serine protease-like β-casein-hydrolyzing activity. The relative activity of this metalloprotease sIgA fraction containing intrinsically bound metal ions increases ∼1.2-1.9-fold after addition of external metal ions (Mg(2+) > Fe(2+) > Cu(2+) ≥ Ca(2+) ≥ Mn(2+)) but decreases by 85 ± 7% after the removal of the intrinsically bound metals. The metalloprotease sIgA fraction free of intrinsic metal ions demonstrates a high β-casein-hydrolyzing activity in the presence of individual external metal ions (Fe(2+) > Ca(2+) > Co(2+) ≥ Ni(2+)) and especially several combinations of metals: Co(2+) + Ca(2+) < Mg(2+) + Ca(2+) < Ca(2+) + Zn(2+) < Fe(2+) + Zn(2+) < Fe(2+) + Co(2+) < Fe(2+) + Ca(2+). The patterns of hydrolysis of a 22-mer oligopeptide corresponding to one of sIgA-dependent specific cleavage sites in β-casein depend significantly on the metal used. Metal-dependent sIgAs demonstrate an extreme diversity in their affinity for casein-Sepharose and chelating Sepharose, and interact with Sepharoses bearing immobilized monoclonal mouse IgGs against λ- and κ-type light chains of human Abs. Possible ways of the production of metalloprotease abzymes (Abz) by human immune system are discussed., (2010 John Wiley & Sons, Ltd.)

Availability of many biological samples in ample quantity for biomedical investigations sometimes is very restricted. Therefore, there is the need for the simple techniques allowing the analysis of small amount samples. In the present work the two-jet plasma atomic emission spectrometry techniques for the determination of Fe, P, Ca, Mg, Zn, and Cu in whole blood are proposed. The first technique is developed for direct analysis of freeze-dried blood. The sample preparation consisted in a dilution of blood powder (particle size 20 microm or less) with a spectroscopic buffer (graphite powder containing 15 wt.% NaCl). For the analysis of liquid whole blood, previous carbonization (not ashing) of blood evaporated on graphite powder was applied. Calibration samples based on graphite powder containing 15 wt.% NaCl were used. The validation of the techniques was confirmed by the use of different sample preparation procedures (wet acid digestion and dry carbonization), the analysis of IAEA A-13 reference material (freeze-dried bovine whole blood), and the comparison of the results obtained by the proposed technique with the results of the stripping voltammetry technique. Just 20-50 microL of whole blood is quite enough for all determinations. The proposed techniques were successfully applied for the simultaneous determination of Fe, P, Ca, Mg, Zn, and Cu in whole blood of living experimental rats and mice and human blood., (Copyright (c) 2009 Elsevier B.V. All rights reserved.)

It was shown that IgGs purified from the sera of healthy Wistar rats contain several different bound Me2+ ions and oxidize 3,3'-diaminobenzidine through a H2O2-dependent peroxidase and H2O2-independent oxidoreductase activity. IgGs have lost these activities after removing the internal metal ions by dialysis against EDTA. External Cu2+ or Fe2+ activated significantly both activities of non-dialysed IgGs containing different internal metals (Fe > or = Pb > or = Zn > or = Cu > or = Al > or = Ca > or = Ni > or = Mn > Co > or = Mg) showing pronounced biphasic dependencies corresponding to approximately 0.1-2 and approximately 2-5 mM of Me2+, while the curves for Mn2+ were nearly linear. Cu2+ alone significantly stimulated both the peroxidase and oxidoreductase activities of dialysed IgGs only at high concentration (> or = 2 mM), while Mn2+ weakly activated peroxidase activity at concentration >3 mM but was active in the oxidoreductase oxidation at a low concentration (<1 mM). Fe2+-dependent peroxidase activity of dialysed IgGs was observed at 0.1-5 mM, but Fe2+ was completely inactive in the oxidoreductase reaction. Mg2+, Ca2+, Zn2+, Al2+ and especially Co2+ and Ni2+ were not able to activate dialysed IgGs, but slightly activated non-dialysed IgGs. The use of the combinations of Cu2+ + Mn2+, Cu2+ + Zn2+, Fe2+ + Mn2+, Fe2+ + Zn2+ led to a conversion of the biphasic curves to hyperbolic ones and in parallel to a significant increase in the activity as compared with Cu2+, Fe2+ or Mn2+ ions taken separately; the rates of the oxidation reactions, catalysed by non-dialysed and dialysed IgGs, became comparable. Mg2+, Co2+ and Ni2+ markedly activated the Cu2+-dependent oxidation reactions catalysed by dialysed IgGs, while Ca2+ inhibited these reactions. A possible role of the second metal in the oxidation reactions is discussed., (Copyright 2008 John Wiley & Sons, Ltd.)

This paper describes an analytical method for trace element determination in bone tissues. The study of the influence of the bone matrix showed that the addition of 25% ground bone to graphite powder with introduced impurities did not affect the analytical signal of elements in the spectral excitation in a two-jet plasma. On basis of these investigations a method for direct multielement analysis of bone tissues was suggested. The sample preparation procedure consisted in mixing powdered bone (particle size 30 μm or less) with a spectroscopic buffer (graphite powder plus NaCl) in ratio 1:3 or to a greater extent depending on the analyte concentration. Reference samples based on graphite powder were used for construction of calibration curves. The NaCl concentration in analyzed and calibration samples was 15 wt%. The effect of particle size was revealed from the determination of Ba, Sr, and Mg. To eliminate this effect, treatment of the samples with nitric acid was proposed. The validation of the technique was confirmed by comparison of the analysis results of a bone sample with those obtained by inductively coupled plasma atomic emission spectrometry after wet acid digestion. The limits of detection estimated for 20 elements were the following (μg g(-1)): 0.1 (Ag), 1.0 (Al), 1.0 (Ba), 0.1 (Be), 1.2 (Bi), 0.4 (Cd), 1.0 (Co), 0.2 (Cu), 0.6 (Cr), 1.9 (In), 2 (Fe), 0.3 (Ga), 0.4 (Mn), 0.4 (Mo), 0.7 (Ni), 1.0 (Pb), 0.7 (Sn), 0.8 (Tl), 5 (Sr), 1.0 (Zn).