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This review describes recent results regarding voltammetric and amperometric determination of submicromolar concentrations of various environmentally important biologically active organic substances using nontraditional types of electrodes either in batch analysis or in flow liquid systems (especially HPLC or FIA with electrochemical detection). Attention is paid to solid amalgam electrodes (environmentally friendly alternatives to mercury electrodes), to carbon paste electrodes with easily renewable surface, to boron doped diamond film electrodes with very low noise and broad potential window, and to inexpensive solid composite electrodes with high signal-to-noise ratio, compatibility with organic solvents and easy mechanical or electrochemical pretreatment. The review concentrates on our own results in the context of the general development in the filed.

The environmental contaminant 2,3,7,8-tetrachlordibenzo-p-dioxin (TCDD) belongs to the category of highly toxic, persistent organic pollutants that accumulate in animal fat and plant tissues. Today, background TCDD levels in human fat are showing a decreasing trend. The food chain is the main source of exposure in the human population. TCDD regulates the expression of a wide range of drug-metabolizing enzymes and has an impact on a large number of biological systems. The most pronounced effects have occurred in occupational settings following the uncontrolled formation of TCDD after industrial accidents, as well as in rare intentional intoxications. Although the acute effects of TCDD exposure are well described in the literature, the long-term consequences have been underevaluated. The most well-known symptoms of severe acute intoxication are chloracne, porphyria, transient hepatotoxicity, and peripheral and central neurotoxicity. Because of the long-term persistence of TCDD in the human body, atherosclerosis, hypertension, diabetes, vascular ocular changes, and signs of neural system damage, including neuropsychological impairment, can be present several decades after massive exposure. Such chronic effects are nonspecific, multifactorial, and may be causally linked to TCDD only in heavily intoxicated subjects. This opinion is supported by the dose-dependent effect of TCDD found in exposed workers and by experimental animal studies.

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The three-dimensional structure of the bovine mitochondrial elongation factor (EF)-Tu⅐Ts complex (EFTu mt ⅐Ts mt ) has been determined to 2.2-Å resolution using the multi-wavelength anomalous dispersion experimental method. This complex provides the first insight into the structure of EF-Ts mt . EF-Ts mt is similar to Escherichia coli and Thermus thermophilus EF-Ts in the amino-terminal domain. However, the structure of EF-Ts mt deviates considerably in the core domain with a fivestranded ␤-sheet forming a portion of subdomain N of the core. In E. coli EF-Ts, this region is composed of a three-stranded sheet. The coiled-coil domain of the E. coli EF-Ts is largely eroded in EF-Ts mt , in which it consists of a large loop packed against subdomain C of the core. Protein biosynthesis is the process by which the ribosome translates the sequence of nucleotides in a mRNA into the sequence of amino acids in a protein. During the cyclic elongation phase, the ribosome is assisted by elongation factors (EFs) 1 (1, 2). In prokaryotes, elongation factor EF-Tu promotes the binding of aminoacyl-tRNA (aa-tRNA) to the A-site of the mRNA-programmed ribosome in the form of the ternary complex aa-tRNA⅐EF-Tu⅐GTP (3). Upon cognate interaction between the codon of mRNA and the anticodon of aa-tRNA, GTP is hydrolyzed, and EF-Tu⅐GDP is released from the ribosome. The nucleotide exchange factor, EF-Ts, binds the EF-Tu⅐GDP complex mediating the release of the GDP and forms a stable EF-Tu⅐Ts complex (1). The high concentrations of GTP in the cell help dissociate EF-Ts leaving the active EF-Tu⅐GTP complex. EF-Tu⅐GTP binds another aa-tRNA, forming a new ternary complex, and the cycle is repeated.Mitochondria contain a highly specialized protein biosynthetic machinery that is responsible for the synthesis of 13 polypeptides of the electron transport chain and the ATP synthase in the inner membrane (4). The mitochondrial translational system has a number of unique features including an altered genetic code, unusual protein-rich ribosomes, and tRNAs that lack many of the conserved residues found in canonical tRNAs (5-7). Despite these differences, mammalian mitochondria possess a translational elongation machinery with significant similarities to that of bacteria (8).Mitochondrial EF-Tu (EF-Tu mt ) is highly conserved and is 55-60% identical to bacterial EF-Tu (9). The three-dimensional structure of the EF-Tu mt ⅐GDP complex has been determined at 1.94-Å resolution (10). The overall structure is similar to that observed in the Escherichia coli and Thermus aquaticus factors, but the nucleotide-binding domain (domain I) of EF-Tu mt is in a different orientation relative to the rest of the structure compared with that observed in prokaryotic 12). Furthermore, domain III is followed by a short 11-amino acid extension that forms one helical turn. This extension seems to be specific to the mitochondrial factors and has not been observed in any of the prokaryotic factors.Bovine liver EF-Ts mt is 338 amino acids in length. The amino terminus of the mat...