Inhibition of erythrocyte acetylcholinesterase by n-butanol at high concentrations

Erythrocyte acetylcholinesterase (AChE) is bound to the membrane by a complex glycosylphosphatidylinositol anchor, so the effect of alcohol on AChE activity may reflect direct and/or membrane-mediated effects. The indication of a direct interaction between n-butanol and AChE molecules is the activation/inhibition of AChE by occupation of the enzyme's active and/or regulatory sites by alcohol. The activation of AChE can occur only at low concentrations of alcohols, while at high concentrations AChE is inhibited. In this work the mechanism of inhibition of erythrocyte AChE by n-butanol at high concentrations was studied. The values of activity, calculated assuming parabolic competitive inhibition, which implies that one or two molecules of inhibitor bind to the enzyme, fit well to the experimental values. From the values of the inhibition constants it was concluded that at high n-butanol concentrations two alcohol molecules usually interact with AChE.     

Synthesis and characterisation of pyrazolic palladium compounds containing alcohol functionality:: rotation around the Pd-N bond

The ligands 1-hydroxymethylpyrazole (hl¹), 1-(2-hydroxyethyl)pyrazole (hl²) and 1-(3-hydroxypropyl)pyrazole (hl³) react with [PdCl₂(CH₃CN)₂] to give trans-[PdCl₂(hl)₂] compounds. Due to a hindered rotation around the Pd-bond, these compounds present two different conformations in solution: anti and syn. The conformation presented depends on the relative disposition of the hydroxyalkylic chains of the two pyrazolic ligands. The present study was carried out on the basis of NMR experiments. The present paper reports the crystal structure of trans-[PdCl₂(hl²)₂]. The synthesis and characterisation of compounds [Pd(hl)₄](BF₄)₂ (hl = hl¹, hl² and hl³) starting from [Pd(CH₃CN)₄](BF₄)₂ and the corresponding chlorocomplexes trans-[PdCl₂(hl)₂] are also described.     

Synthesis of R and S tritiated reduced beta-nicotinamide adenine dinucleotide 2' phosphate

Nicotinamides are ubiquitous cofactors used by many biological systems as redox agents. Stereospecifically labeled cofactors are useful in many studies of nicotinamide-dependent enzymes. Enzyme-directed synthesis of these cofactors is rather common but their stability imposes significant challenges on yield, purity, and preservation. This paper presents the stereospecific synthesis of reduced R- and S-[4-3H] beta-nicotinamide adenine dinucleotide 2' phosphate (NADPH). The method of Valera et al. [Biochem. Biophys. Res. Commun. 148 (1987) 515] was modified to a synthetic procedure that produces both isotopic diastereomers within 2h with an improved yield of 75-90% after purification and lyophilization. In the synthesis, [4-3H]NADP+ was generated as an intermediate (which can be isolated if desired). The specific radioactivities reported here are 2.7 and 1.1 Ci/mmol for the S and R diastereomers, respectively. Specific radioactivities ranging from carrier-free to trace labeling can be achieved with a minor change to the procedure.     

Yeast cytochrome c is a sequence-specific DNA-binding protein

A protein binding to the alcohol oxidase 2 upstream activation sequence (AOX2UAS) of the methylotropic yeast, Pichia pastoris, has been purified and identified as cytochrome c (cyt c). Cyt c purified from P. pastoris or Saccharomyces cerevisiae binds to AOX2UAS. Specific point mutations in AOX2UAS abolish cyt c binding. We conclude that yeast cyt c is a sequence-specific DNA-binding protein and may have a regulatory role in the nucleus.     

Functional Constraints of Alcohol Dehydrogenase (ADH) of Tephritidae and Relationships with Other Dipteran Species

Alcohol dehydrogenase is considered a very important enzyme in insect metabolism because it is involved (in its homodimeric form) in the catalysis of the reversible conversion of various alcohols in larval feeding sites to their corresponding aldehydes and ketones, thus contributing to detoxification and metabolic purposes. Using 14 amino acid ADH sequences recently determined in our laboratory, we constructed a three-dimensional (3D) model of olive fruit fly Bactrocera oleae ADH1 and ADH2, based on the known homologous Drosophila lebanonensis ADH structure, and the amino acid residues that have been proposed as being responsible for catalysis were located on it. Moreover, in a comparative study of the ADH sequences, the residues occupying characteristic positions in the ADH of species of the Bactrocera and Ceratitis genera (called genus-specific) as well as residues appearing only in ADH1 or ADH2 (called isozymic-specific) were defined and localized on the 3D model. All regions important for catalytic activity, such as those forming the substrate- and coenzyme-binding sites, are highly conserved in all tephritid species examined. Genus-specific amino acids are located on the outside of the protein, on loops and regions predicted to be antigenic. The higher percentage of genus-specific amino acid variation seems to be centered in the NAD adenine-binding site, located near the surface of the protein molecule. Nine of 12 isozymic-specific positions are lined along an arc on the surface of the protein, thus linking the two monomer bases of the dimer via the C-terminal interacting loops. Furthermore, the distribution of isozymic- and genus-specific amino acids on the monomer–monomer interface may have some evolutionary significance. Most amino acids predicted to be antigenic are positioned in peripheral regions of nonfunctional importance, but surprisingly, an additional antigenic region is contained within the (highly conserved in tephritids) C-terminal tail.     

Dopamine and cyclic AMP-regulated phosphoprotein-32 phosphorylation pattern in cocaine and morphine-sensitized rats

This study reports some of the modifications in dopaminergic signalling that accompany cocaine and morphine behavioural sensitization. Cocaine-sensitized rats showed increased phosphorylation of dopamine- and cyclic AMP-regulated phosphoprotein Mr 32 kDa (DARPP-32) at threonine-75 (Thr75) and decreased DARPP-32 phosphorylation at Thr34, in the caudate-putamen (CPu) and nucleus accumbens (NAc) 7 days after sensitization assessment. Conversely, in morphine-sensitized rats, no apparent modifications in DARPP-32 phosphorylation pattern were observed. Morphine-sensitized rats have increased binding and coupling of micro -opioid receptors and increased dopaminergic transmission in striatal areas and, upon morphine challenge, exhibit dopamine D1 receptor-dependent stereotypies. Thus, the DARPP-32 phosphorylation pattern was studied in morphine-sensitized rats at different times after morphine challenge. Morphine challenge increased levels of phospho-Thr75 DARPP-32 and decreased levels of phospho-Thr34 DARPP-32 in a time-dependent manner in the CPu and NAc. In order to assess whether these modifications were related to modified cyclic AMP-dependent protein kinase (PKA) activity, the phosphorylation levels of two other PKA substrates were examined, the GluR1 and NR1 subunits of alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate and NMDA receptors respectively. The phosphorylation levels of GluR1 and NR1 subunits decreased in parallel with those of phospho-Thr-34 DARPP-32, supporting the hypothesis that morphine challenge elicited a decrease in PKA activity in morphine-sensitized rats.     

Stabilities and rates in the laccase/TEMPO-catalyzed oxidation of alcohols

The influence of alcohol, 4-acetylamino,2,2,6,6'-tetramethylpiperidinyloxy (4-acetylamino-TEMPO) and laccase (from Trametes versicolor, TvL) concentration in the aerobic oxidation of furfuryl alcohol was investigated. Studies show that the K _m for 4-acetylamino-TEMPO is around 6.3 mM (V _max=0.18 mM min^-1) using 6.6 U mL^-1 of laccase and a furfuryl alcohol concentration of 140 mM. Under these optimized conditions, the reaction rate is still dependent on the concentration of enzyme in solution. Laccase can be reused, with a residual activity of around 25%. An important conclusion is that laccase is not stable in the presence of oxoammonium salts, presumably due to degradation via oxidation of essential amino acid residues or the glycosyl moieties on the periphery of the enzyme.     

药（毒）物对尸食性蝇类生长发育影响的研究进展

药（毒）物对尸食性蝇类生长发育影响是法医昆虫毒理学领域里一个十分重要的研究方向,其研究结果可对与药（毒）物相关死亡案件的死亡时间作出修正。随着近年来全球毒品及药物滥用情况的日趋严重,其所导致的死亡案件也越来越多。这类案件常常需要应用尸食性蝇类生长发育历期来推算死后经历时间（postmortem interval, PMI）。为了阐明该领域的研究进展以及未来研究的焦点和难点,本文在阐述法医昆虫毒理学概念和特点的基础上,按照不同的药（毒）物分类,对近年来药（毒）物对尸食性蝇类生长发育影响在国内外的研究进展进行了综述。研究表明,某些药（毒）物对尸食性蝇类生长发育具有一定的影响,且这种影响存在种属差异。目前,该领域的研究尚限于宏观现象观察阶段,其研究范围在不断拓宽,既有的研究也在进一步深化,但还有许多问题有待进一步探讨。     

黄瓜香水、醇提取液对肠道菌群的调整作用的比较

目的研究不同溶剂提取黄瓜香有效成分的作用效果,以期能更好提高药物的利用度。方法用盐酸林可霉素制造小鼠菌群失调模型,然后分别用黄瓜香的水、醇提取物治疗,比较治疗效果。结果醇提取物和水提取物均能调整肠道菌群平衡,与自然恢复组相比差异有统计学意义(P0.05),且醇提取物组效果要优于水提取物组(P0.05)。结论黄瓜香醇提取物是理想的微生态调节剂。