As is found by atomic absorption spectroscopy, the highly purified bovine tryptophanyl-tRNA synthetase contains up to 0.9 mol Zn2+/mol enzyme while some other bivalent metal ions are absent. The enzyme is inactivated either upon treatment with 1 ,lO-phenanthroline (a zinc-chelating agent) or upon prolonged dialysis (which eliminates bound Zn2+ ions); addition of zinc reactivates the enzyme. Exposed histidine residue(s) and carboxylic group(s) of the enzyme are involved in the Zn2+ binding, as is shown using chemical modification. Circular dichroism spectra suggest that elimination of Zn2 + ions affects the tertiary rather than the secondary structure of the tryptophanyl-tRNA synthetase. The kinetics of inhibition with 1,lO-phenanthroline toward ATP, tryptophan and tRNATrp indicates that removal of zinc prevents the ATP binding to the enzyme.Many enzymes of nucleic acid metabolism, viz. D N A polymerase, RNA polymerase, terminal nudeotidyltransferase, poly(A) polymerase, etc. (see [1,2]), contain zinc ions. These enzymes are inactivated in the presence of 1 ,lo-phenanthroline, a chelating agent with a high affinity for ZnZt [3].It has long been known that the activity of certain Eschcvichiu coli aminoacyl-tRNA synthetases is inhibited with phenanthroline [4]. Hence, bivalent metal (iron, cadmium, zinc, or manganese) ions may be involved in the functioning of these enzymes. Zinc essential for the activity and manganese have recently been found in E. coli methionyl-tRNA synthetase [5]. Zinc ions are involved in the tRNA-independent ATP hydrolysis catalyzed by yeast phenylalanyl-tRNA synthetase [6]. The Zn2+ ion (0.94 mol/mol enzyme) unessential for the aminoacylation activity has been found in E. coli isoleucyl-tRNA synthetase [7].The purpose of this work is to clarify whether tryptophanyl-tRNA synthetase ( M , 120000, ~2 ) from beef pancreas belongs to the group of metalloenzymes and what is the role of zinc in the enzymatic functioning. This enzyme is the best studied aminoacyl-tRNA synthetase from multicellular organisms [8]. MATERIALS AND METHODSThe following reagents were used in the experiments : ATP, Tris (Reanal) ; L-tryptophan (Sigma) ; sodium pyrophosphate (Merck) ; dithiothreitol, diethylpyrocarbonate and 4-niorpholinepropanesulfonic acid (Mops, Serva) ; 2-mercaptoethanol (Calbiochem); cetyltrimethylammonium bromide (cetavlon) and nitrocellulose filters Synpor 3 and 6 (Chemapol); chelating resin Chelex-100 (Bio-Rad); Sephadex (3-100 and (3-50, fine grade (Pharmacia Fine Chemicals); diphenylthiocarbazone (ditizone), 1,lO-phenanthroline and Tryptophanyl-tRNA synthetase was isolated from beef pancreas as described elsewhere [8]. The preparation was homogeneous after gel electrophoresis under denaturing conditions. The protein concentration was determined spectrophotometrically at 280 nm using the coefficient A@,,, = 0.90 [8]. The activity of tryptophanyl-tRNA synthetase in the ATP-[32P]pyrophosphate exchange and the tRNA aminoacylation reactions was assayed as in [8].Solutions were prepared with deionized...

Preeclampsia (PE) and gestational diabetes mellitus (GDM) are the most common complications of pregnancy, which result in adverse outcomes for the mother and the fetus. GDM is regarded as a separate independent risk factor for PE development, as evidenced by a higher preeclampsia rate in gestational diabetes mellitus than in the general population. The role the endothelial cell dysfunction plays is considered to be the most reasonable one in the origin of these diseases. The activity of plasma and tissue angiotensin converting enzyme (ACE) is believed to be genetically controlled. The available data suggests that increased ACE activity due to deletion (D)/insertion (I) in the 16th intron of ACE gene, which is called ACE gene I/D polymorphism, is associated with preeclampsia and varies depending on the studied population and the geography. We did not find any literature data that estimates the influence of ACE gene I/D polymorphism on PE rate in pregnant women with GDM. Therefore, the present study aimed to investigate a relationship between ACE gene I/D polymorphism and preeclampsia development in the case of GDM in the Russian population. The study used the genomic DNA derived by phenol-chloroform extraction method from venous blood samples in 137 pregnant women, including samples of 74 women with GDM accompanied with PE and the blood samples of 63 women with GDM w/o preeclampsia. Genotyping of insertion/deletion in the I/D region (16 intron of АСЕ gene) was conducted by real-time PCR using the TaqMan competing probe technology. The particular features in the frequency array of alleles and genotypes of the ACE gen I/D polymorphism under review, as associated with preeclampsia development risk in pregnant women with GDM, were identified. The acquired data testify to the need to further study of ACE gene I/D region polymorphism association in a large patient sample taking into account the PE and GDM risk factors estimated in the clinical practice.

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In vitro experiments performed on rabbits showed that tris-2-(hydroxyethyl)ammonium orthocresoxyacetate (trecrezan) increases the cytokine activity of total tryptophanyl mRNA synthase (TRSase) via stimulation of the synthesis of a specific mRNA synthase (TRSase). This explains the mechanisms of the hypolipidemic, immunomodulatory, and adaptogenic actions of trecrezan.