Amino acids and peptides. X. Synthesis of two dotriacontapeptides corresponding to C-terminal sequence 30–61 (fragment α) of human liver metallothionein II and their heavy metal binding properties

Two kinds of dotriacontapeptides corresponding to C-terminal sequence 30–61 of human liver metallothionein, both containing 11 cysteine residues, were synthesized by the conventional fragment condensation method employing the HF deprotection or MSA deprotection method at the final step. Their heavy metal (Zn, Cd, or Cu) binding activity was examined, and it was found that their heavy metal binding properties were quite similar to those of native human liver thionein.     

The relationship between co-exposure to multiple heavy metals and liver damage

BackgroundThe impact of heavy metal exposure on human health has attracted widespread attention of researchers, and the impact of heavy metal exposure on liver function has also been confirmed, however, more attention is paid to the impact of single or two heavy metal exposures, and most epidemiological studies focus on heavy metal pollution areas. In this study, rural residents in non-heavy metal-contaminated areas in Northwest China were selected as the research objects to explore the comprehensive effects of co-exposure to multiple heavy metals on the liver, which can provide certain reference and support for related research.ObjectivesThis study used a Bayesian nuclear machine model (BKMR) to evaluate the relationship between exposure to heavy metal mixtures and indicators of liver function in a population in rural Northwest China.ResultsExposure to higher concentrations of metal mixtures was positively correlated with total bilirubin, direct bilirubin, and aspartate aminotransferase, and negatively correlated with alanine aminotransferase, with Pb contributing the most to indicators of liver function. We also observed a possible interaction of Cd with other heavy metals in the effect of heavy metal mixtures on DB levels.ConclusionsConcurrent exposure to higher concentrations of heavy metal mixtures (Cr, Co, Cd, and Pb) in rural China was associated with indicators representing poor liver function, of which the effect of lead on liver function should be focused. More prospective epidemiological studies and animal experiments need to be carried out to determine this relationship and possible mechanism.     

Immunohistochemical localization of alpha1-acid-glycoprotein in human liver parenchymal cells.

alpha1-Acid glycoprotein, a major human serum glycoprotein was detected and localized in human liver parenchymal cells of a biopsy specimen. A heavy metal salt containing fixative was required to retain sufficient antigen determinants of alpha1-acid glycoprotein in order to visualize this protein by the peroxidase-anti-peroxidase unlabeled antibody enzyme method.     

Phytochelatins and heavy metal tolerance

The induction and heavy metal binding properties of phytochelatins in heavy metal tolerant (Silene vulgaris) and sensitive (tomato) cell cultures, in water cultures of these plants and in Silene vulgaris grown on a medieval copper mining dump were investigated. Application of heavy metals to cell suspension cultures and whole plants of Silene vulgaris and tomato induces the formation of heavy metal–phytochelatin-complexes with Cu and Cd and the binding of Zn and Pb to lower molecular weight substances. The binding of heavy metal ions to phytochelatins seems to play only a transient role in the heavy metal detoxification, because the Cd- and Cu-complexes disappear in the roots of water cultures of Silene vulgaris between 7 and 14 days after heavy metal exposition. Free heavy metal ions were not detectable in the extracts of all investigated plants and cell cultures. Silene vulgaris plants grown under natural conditions on a mining dump synthesize low molecular weight heavy metal binding compounds only and show no complexation of heavy metal ions to phytochelatins. The induction of phytochelatins is a general answer of higher plants to heavy metal exposition, but only some of the heavy metal ions are able to form stable complexes with phytochelatins. The investigation of tolerant plants from the copper mining dump shows that phytochelatins are not responsible for the development of the heavy metal tolerant phenotypes.     

A novel heavy metal ATPase peptide from <Emphasis Type="Italic">Prosopis juliflora</Emphasis> is involved in metal uptake in yeast and tobacco

Heavy metal pollution of agricultural soils is one of the most severe ecological problems in the world. Prosopis juliflora, a phreatophytic tree species, grows well in heavy metal laden industrial sites and is known to accumulate heavy metals. Heavy Metal ATPases (HMAs) are ATP driven heavy metal pumps that translocate heavy metals across biological membranes thus helping the plant in heavy metal tolerance and phytoremediation. In the present study we have isolated and characterized a novel 28.9 kDa heavy metal ATPase peptide (PjHMT) from P. juliflora which shows high similarity to the C-terminal region of P_1B ATPase HMA1. It also shows the absence of the invariant signature sequence DKTGT, and the metal binding CPX motif but the presence of conserved regions like MVGEGINDAPAL (ATP binding consensus sequence), HEGGTLLVCLNS (metal binding domain) and MLTGD, GEGIND and HEGG motifs which play important roles in metal transport or ATP binding. PjHMT, was found to be upregulated under cadmium and zinc stress. Heterologous expression of PjHMT in yeast showed a higher accumulation and tolerance of heavy metals in yeast. Further, transgenic tobacco plants constitutively expressing PjHMT also showed increased accumulation and tolerance to cadmium. Thus, this study suggests that the transport peptide from P. juliflora may have an important role in Cd uptake and thus in phytoremediation.     

重金属结合肽（蛋白）的结构分析

金属离子与金属结合肽（蛋白）的相互作用与应用研究,一直是生物无机化学的重点和热点,也是分子间相互作用研究领域的难点。本研究利用ClustalX、BLAST等生物信息技术与方法对大量已知的重金属结合肽进行分析与数据挖掘。确定筛选获得的重金属结合肽常富含His,无Cys,无金属结合肽模式序列,进化不保守;部分氨基酸序列结构（如六肽）可在蛋白数据库中找到相似序列。序列特征主要为Zn^2＋相关的转录因子。本研究为重金属结合蛋白-重金属离子的相互作用分析简化为重金属结合肽-重金属离子的结构模拟与分析提供了重要的理论基础和研究手段。     

From industrial sites to environmental applications with <Emphasis Type="Italic">Cupriavidus metallidurans</Emphasis>

Cupriavidus metallidurans CH34 and related strains are adapted to metal contaminated environments. A strong resistance to environmental stressors and adaptation make it ideal strains for survival in decreasing biodiversity conditions and for bioaugmentation purposes in environmental applications. The soil bacterium C. metallidurans is able to grow chemolithoautotrophically on hydrogen and carbon dioxide allowing a strong resilience under conditions lacking organic matter. The biofilm growth on soil particles allows coping with starvation or bad conditions of pH, temperature and pollutants. Its genomic capacity of two megaplasmids encoding several heavy metal resistance operons allowed growth in heavy metal contaminated habitats. In addition its specific siderophores seem to play a role in heavy metal sequestration besides their role in the management of bioavailable iron. Efflux ATPases and RND systems pump the metal cations to the membrane surface where polysaccharides serve as heavy metal binding and nucleation sites for crystallisation of metal carbonates. These polysaccharides contribute also to flotation under specific conditions in a soil-heavy metals–bacteria suspension mixture. An inoculated moving bed sand filter was constructed to treat heavy metal contaminated water and to remove the metals in the form of biomass mixed with metal carbonates. A membrane based contactor allowed to use the bacteria as well in a versatile wastewater treatment system and to grow homogeneously formed heavy metal carbonates. Its behaviour toward heavy metal binding and flotation was combined in a biometal sludge reactor to extract and separate heavy metals from metal contaminated soils. Finally its metal-induced heavy metal resistance allowed constructing whole cell heavy metal biosensors which, after contact with contaminated soil, waste, solids, minerals and ashes, were induced in function of the bioavailable concentration (Cd, Zn, Cu, Cr, Co, Ni, Tl, Pb and Hg) in the solids and allowed to investigate the speciation of immobilization of those metals. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Metal accumulation and metallothionein in brown trout, Salmo trutta, from two Norwegian rivers differently contaminated with Cd, Cu and Zn

In this work we have studied the accumulation of heavy metals in two brown trout (Salmo trutta) populations in their natural environment and the participation of metal binding to metallothionein (MT) in this process. Cd, Cu and Zn concentrations, total MT (including Cu MT) and Cd/Zn MT were measured in the gills, liver and kidney of trout inhabiting two rivers, one Cu-contaminated and the other Cd/Zn-contaminated, located at Røros, Central Norway. In both populations, high levels of Cu were found in the liver, whereas Cd was accumulated in liver and particularly in the kidney. The proportions of Cd/Zn MT and Cu MT in liver and kidney, but not in gills, reflected the accumulated and the environmental concentrations of these metals. The total Cu MT concentrations in the investigated tissues, however, were highest in trout from the river with the lowest ambient Cu concentration. It is suggested that MTs are of less importance in Cu-acclimated trout. The data also suggest that acclimation to a Cu-rich environment involves reduced Cu accumulation or increased Cu elimination. In trout from the Cd-rich environment, this metal was mainly bound to MT, whereas in trout from the Cu-rich environment Cd was also associated with non-MT proteins. These findings emphasize the importance to determine both Cd/Zn MT and Cu MT levels, when the participation of this protein in metal handling in trout tissues is investigated.     

Heavy metal-mediated activation of the rat Cu/Zn superoxide dismutase gene via a metal-responsive element

The Cu/Zn superoxide dismutase (SOD1) catalyzes the dismutation of superoxide radicals produced in the course of biological oxidations. When placed under the control of the rat SOD1 gene promoter and transfected into human HepG2 hepatoma cells, the activity of a chloramphenicol acetyltransferase reporter gene was found to increase three- to four-fold in the presence of heavy metals (cadmium, zinc and copper). Functional analysis of mutant derivatives of the SOD1 gene promoter and the use of a heterologous promoter system confirmed that the induction of the SOD1 gene by metal ions requires a metal-responsive element (MRE) located between positions −273 and −267 (GCGCGCA). It was also shown by gel mobility shift assays that an MRE binding protein is induced by the exposure of the human liver cell line HepG2 to heavy metals. These results suggest that the MRE participates in the induction of the SOD1 gene by heavy metals. Received: 5 February 1999 / Accepted: 21 May 1999     

Immunological studies on the interaction of polyadenylic acid and human liver ribonuclease

The effect of polyadenylic acid, a potent inhibitor of mammalian and bacterial RNAses, on the binding of human liver RNAse to its antibody was studied. To do this, a human liver RNAse antibody was immobilized on Sepharose 4B. Examination of the ability of the enzyme to bind to the immobilized anti-RNAse in the presence or absence of polyadenylic acid indicated that enzyme-antibody binding was more sensitive to the presence of polyadenylic acid than was enzyme activity. Furthermore, the effect of polyadenylic acid on enzyme-antibody binding was specific since neither polycytidylic acid nor polyuridylic acid had much effect on the antigenicity of the enzyme. The metal cation, Mg2+, and the polyamine, spermidine, but not putrescine, readily reversed the effects of polyadenylic acid on enzyme-antibody binding.