Structural and catalytic polymorphism of human enzymes: Novel potential platforms for biomedical diagnostics

This review focuses on some intermediate results on the path from the gene and enzyme structure to physiological responses and personalised medicine. Bioinformatics of genetic and protein-structural polymorphisms, theoretical methods of predicting the influence of single amino acid substitutions on the structure and catalytic activity of enzymes are considered. For a large group of enzymes, interrelations between genetic modifications, structural changes of the proteins and the detected physiological and clinical manifestations are discussed. In this respect, highly productive techniques to determine the catalytic activity of an enzyme as well as non-invasive proteomic approaches are of particular interest. A non-invasive proteomic analysis using mass-spectrometric protein identification of human exhaled breath condensate and tear fluids has been chosen.     

High throughput characterization of structural differences between closely related proteins in solution

Partitioning of a protein in an aqueous two-phase system (ATPS) is governed by interactions of the protein with aqueous media in the two phases. Here we describe how partitioning of proteins in a set of ATPS of different compositions can be used to quantify differences between 3D structures of closely related proteins. We also provide perspective on practical applications of the technology when comparative analysis of the higher-order structure of proteins is desired.     

Growth and Secondary Metabolite Production by Hairy Roots of Tagetes Patula in Aqueous Two-Phase Systems

Hairy roots of Tagetes patula have been grown in aqueous two-phase systems. After selecting suitable polymers from single-phase experiments (in which salt phases were unable to support growth in the desired concentrations) several two-phase systems were tested for their influence on cell growth and thiophene production. Cell growth occurred in all aqueous two-phase systems, but the highest growth rate was achieved in normal medium. There was no difference in thiophene production between medium and aqueous two-phase systems. The partition of thiophenes favoured slightly the more hydrophobic top phase in most cases, while the cells were confined to the bottom phase. One aqueous two-phase system (15% polyethyleneglycol 10,000 and 15% Reppal PES 200) was tested in a stirred tank reactor with normal medium as a control. The growth rate in medium was higher than in the aqueous two-phase system, while the thiophene production per unit cell weight was in the same range for both systems. The excretion of thiophenes in the reactor with the aqueous two-phase system was about ten times as high as in the control reactor. The amount excreted was however still not more than 3% of the total production.     

Study of human cord blood lymphocytes by immobilized metal ion affinity partitioning

The potential of immobilized metal ion affinity partitioning (IMAP) using dextran-PEG+PEG-IDA-M(II) systems to separate mononuclear cells from cord blood has been evaluated. The distribution of B cells, T cells, monocytes and hematopoietic stem cells between PEG and dextran phases was determined by flow cytometry with fluorochrome-labelled specific antibodies. Comparing these values with the post-Ficoll repartition resulted in the determination of enrichment factors, for each subpopulation, in the different phases. We were able to distinguish the partition pattern of B cells, T cells, monocytes and stem cells in different IMAP systems. Their partition was affected by the nature and the concentration of the metal used, but no specificity in distribution for the subpopulations was found.     

Facile synthesis of substituted thiophenes via Pd/C-mediated sonogashira coupling in water

The first successful Pd/C-mediated Sonogashira coupling of iodothiophene with terminal alkynes in water is described here. Pd/C-CuI-PPh₃ was found to be an efficient catalyst system for this coupling reaction. Using this economic and reliable process a variety of acetylenic thiophenes with a wide range of functional groups were prepared in good yields. Synthetic applications and in vitro anticancer properties of some of the compounds synthesized are described.     

Effects of the invasive plant Mikania micrantha H.B.K. on soil nitrogen availability through allelopathy in South China

Allelopathy has been regarded as a mechanism for successful exotic plant invasion. However, it is not clear if and what effects of allelopathic substances may exert on soil nutrient. The exotic plant Mikania micrantha H.B.K. (M. micrantha) has invaded many forests in south China, and recent studies have suggested it has allelopathic potential for other plants and soil microbial community. Thus, we hypothesized that M. micrantha could influence soil nutrients and N transformation through allelopathy. We measured total C and N, NO₃ ⁻, NH₄ ⁺ and pH of the soil beneath M. micrantha and the adjacent open soil, and then measured the above soil properties after treating soil with 3 concentrations of aqueous extracts of M. micrantha (T₁: 0.005 g ml⁻¹; T₂: 0.025 g ml⁻¹; T₃: 0.100 g ml⁻¹). In addition, a bioassay was conducted to determine the allelopathic potential of the soil beneath M. micrantha. The results showed that M. micrantha significantly affected soil nutrients and N transformation. Soil beneath M. micrantha had inhibitory effects on seed germination and seedling growth of test plant, and had significantly higher C, N, ammonia, net nitrification rate than those of open soil. The plant extracts decreased soil pH, and T₁ decreased it the most, and it increased soil C and N, and T₁ represented the greatest increase in both C and N. The extracts also increased both NO₃ ⁻ and NH₄ ⁺ in soil, whereas no significant difference existed among the 3 extract treatments. Compared to the water control, the soil net mineralization rate was higher under T₁, while lower under T₂ and T₃. However, the extracts increased the soil nitrification rates under all the treatments (T₁, T₂ and T₃). Our results suggest that the water soluble allelochemicals of M. micrantha improve soil nutrient availability, through which the invasive plant M. micrantha may successfully invade and establish in new habitats.     

Partial molar volumes of some α-amino acids in aqueous sodium acetate solutions at 308.15 K

The apparent molar volumes V_2,φ have been determined for glycine, -α-alanine, -α-amino-n-butyric acid, -valine and -leucine in aqueous solutions of 0.5, 1.0, 1.5 and 2.0 mol kg⁻¹ sodium acetate by density measurements at 308.15 K. These data have been used to derive the infinite dilution apparent molar volumes V⁰_2,φ for the amino acids in aqueous sodium acetate solutions and the standard volumes of transfer, Δ_tV⁰, of the amino acids from water to aqueous sodium acetate solutions. It has been observed that both V⁰_2,φ and Δ_tV⁰ vary linearly with increasing number of carbon atoms in the alkyl chain of the amino acids. These linear correlations have been utilized to estimate the contributions of the charged end groups (NH₃⁺,COO⁻), CH₂ group and other alkyl chains of the amino acids to V⁰_2,φ and Δ_tV⁰. The results show that V⁰_2,φ values for (NH₃⁺,COO⁻) groups increase with sodium acetate concentration, and those for CH₂ are almost constant over the studied sodium acetate concentration range. The transfer volume increases and the hydration number of the amino acids decreases with increasing electrolyte concentrations. These facts indicate that strong interactions occur between the ions of sodium acetate and the charged centers of the amino acids. The volumetric interaction parameters of the amino acids with sodium acetate were calculated in water. The pair interaction parameters are found to be positive and decreased with increasing alkyl chain length of the amino acids, suggesting that sodium acetate has a stronger dehydration effect on amino acids which have longer hydrophobic alkyl chains. These phenomena are discussed by means of the cosphere overlap model.     

Reinvestigation of the mercuration-demercuration reaction on alkylated glycals: an improved method for the preparation of 2,3-dideoxy-alpha,beta-unsaturated carbohydrate enals

Alkyl protected glycals can be easily converted into their corresponding alpha,beta-unsaturated enals (Perlin aldehydes) in good to very good yields by reaction with HgSO4 and aqueous 0.02 N H2SO4 in THF or 1,4-dioxane. While the formation of Perlin aldehydes from benzyl-protected glucal and arabinal was accomplished by refluxing the reaction mixture in 1,4-dioxane, the benzyl-protected galactal and methyl-protected glucal, galactal, and arabinal yielded aldehydes from this reaction at room temperature using THF or 1,4-dioxane as solvent.     

Crystal structure of ammonium isosaccharate and aqueous solubility of ammonium and sodium isosaccharates

Ammonium isosaccharate, C6H15NO6.H2O (NH4-ISA), has been synthesized and its crystal structure solved by single-crystal X-ray diffraction methods. NH4-ISA crystallizes in the monoclinic space group P2(1) (#4) with cell parameters a=8.6470(12)A, b=5.0207(7)A, c=9.8193(14)A, beta=91.643(3) degrees , V=426.12(10)A3, Z=2. The structure was refined by full-matrix least-squares on F2 yielding final R-values (all data) R1=0.0485 and Rw2=0.1104. The structure consists of alternating (NH4)+ and (C6H11O6)- layers parallel to the ab plane. An extended network of O-H...O intermolecular (ISA)...(ISA) hydrogen bonds links the (ISA)- anions within the ab plane, while the 3-D connectivity along the c-axis is provided only by (ISA-)...(NH4+)...(ISA-) hydrogen bonds. The aqueous solubility (Si, [ML(-1)]) of NH4- and Na-ISA has been shown to be pH independent at ambient conditions within the range 4.5相似文献   

Constituents of Pterocarpus marsupium: an ayurvedic crude drug

Five new flavonoid C-glucosides, 6-hydroxy-2-(4-hydroxybenzyl)-benzofuran-7-C-beta-d-glucopyranoside (1), 3-(alpha-methoxy-4-hydroxybenzylidene)-6-hydroxybenzo-2(3H)-furanone-7-C-beta-d-glucopyranoside (2), 2-hydroxy-2-p-hydroxybenzyl-3(2H)-6-hydroxybenzofuranone-7-C-beta-d-glucopyranoside (4), 8-(C-beta-d-glucopyranosyl)-7,3',4'-trihydroxyflavone (5) and 1,2-bis(2,4-dihydroxy,3-C-glucopyranosyl)-ethanedione (6) and two known compounds C-beta-d-glucopyranosyl-2,6-dihydroxyl benzene (7) and sesquiterpene (8), were isolated from an aqueous extract of the heartwood of Pterocarpus marsupium. The structure has been established using spectroscopic data.