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Thalassospiramides A and B are immunosuppressant cyclic lipopeptides first reported from the marine α-proteobacterium Thalassospira sp. CNJ-328. We describe here the discovery and characterization of an extended family of 14 new analogues from four Tistrella and Thalassospira isolates. These potent calpain 1 protease inhibitors belong to six structure classes in which the length and composition of the acylpeptide side chain varies extensively. Genomic sequence analysis of the thalassospiramide-producing microbes revealed related, genus-specific biosynthetic loci encoding hybrid nonribosomal peptide synthetase/polyketide synthases consistent with thalassospiramide assembly. The bioinformatics analysis of the gene clusters suggests that structural diversity, which ranges from the 803.4 Da thalassospiramide C to the 1291.7 Da thalassospiramide F, results from a complex sequence of reactions involving amino acid substrate channeling and enzymatic multimodule skipping and iteration. Preliminary biochemical analysis of the N- terminal nonribosomal peptide synthetase module from the Thalassospira TtcA megasynthase supports a biosynthetic model in which in cis amino acid activation competes with in trans activation to increase the range of amino acid substrates incorporated at the N terminus. [ABSTRACT FROM AUTHOR]

Peptidomics is a powerful set of tools for the identification, structural elucidation and discovery of novel regulatory peptides and for monitoring the degradation pathways of structurally and catalytically important proteins. Amphibian skin secretions, arising from specialized granular glands, often contain complex peptidomes containing many components of entirely novel structure and unique site-substituted analogues of known peptide families. Following the discovery that the granular gland transcriptome is present in such secretions in a PCR-amenable form, we designed a strategy for peptide structural characterization involving the integration of ‘shotgun’ cloning of cDNAs encoding peptide precursors, deduction of putative bioactive peptide structures, and confirmation of these structures using tandem MS/MS sequencing. Here, we illustrate this strategy by means of elucidation of the primary structures of nigrocin-2 homologues from the defensive skin secretions of four species of Chinese Odorrana frogs, O. schmackeri, O. livida, O. hejiangensis and O. versabilis. Synthetic replicates of the peptides were found to possess antimicrobial activity. Nigrocin-2 peptides occur widely in the skin secretions of Asian ranid frogs and in those of the Odorrana group, and are particularly well-represented and of diverse structure in some species. Integration of the molecular analytical technologies described provides a means for rapid structural characterization of novel peptides from complex natural libraries in the absence of systematic online database information. [ABSTRACT FROM AUTHOR]

The molecular structure of the title compound, C14H10O4Se2- 2C3H7NO, reveals Ci symmetry, with the inversion centre located at the mid-point of the Se Se bond. Diselenide derivatives are important in the synthesis of ebselen and other organoselenium compounds. These derivatives are of interest owing to their biological activity as oxidoreductans. The structure displays an O—H⋯O hydrogen bond between the carboxyl group and the carbonyl unit of the dimethylformamide solvent molecule. [ABSTRACT FROM AUTHOR]

Samples of groundwater, river water, river sediment, paddy soil, rice seeds, hen eggs, fish, umbilical cord blood, and newborn meconium were collected from October 2002 to October 2003 near a large site in China used for the disassembly of obsolete transformers and other electronic or electrical waste. Six indicator PCB congeners, three non- ortho dioxin-like PCB congeners, and six organochlorine pesticides were determined in the samples by GC with electron capture detector. The results demonstrated that the local environment and edible foods had been seriously polluted by toxic PCBs and organochlorine pesticides. The actual daily intakes (ADIs) of these pollutants were estimated for local residents living in the area. The intake data showed that the contents of PCBs in these local residents were substantial, as the ADI estimates greatly exceed the reference doses set by the World Health Organization and the United States Agency for Toxic Substances and Disease Registry. The presence of the indicator PCB congeners in the cord blood and the meconium samples, as well as significant correlations ( r² > 0.80, p < 0.05) between these levels, suggests a potential biotransfer of these indicators from mothers to their newborns. This preliminary study showed that obsolete transformers and other electronic or electrical waste can be an important source for the emission of persistent organic pollutants into the local environment, such as through leakage, evaporation, runoff, and leaching. Contamination from this source appears to have reached the level considered to be a serious threat to environmental and human health around the disassembly site. [ABSTRACT FROM AUTHOR]

Humic substrates are a major fraction of sediment organic matters, and the sorption of hydrophobic organic chemicals by humic substrates influences their behavior and fate in sediment. In this paper, organic matters were divided into non-humic substrates and humic substrates. Non-humic substrates include acid leaching fraction, acid extracted fraction, and lipid; humic substrates were fractionated into Ca-binding-FA (fulvic acid), Ca-binding-HA (humic acid), oxide-FA, oxide-HA, and humin. To study the effect of organic fractions on sorption properties, sorption kinetic and equilibrium sorption experiments of phenanthrene and pentachlorophenol (PCP) in five sediments were carried out. The results showed that the contents of acid leaching fraction and oxide-binding-HA were the main fractions to affect the sorption rate constant, and for the sorption capacity of phenanthrene, humin was the major fraction, followed by oxide-binding-HA, oxide-binding-FA, and so on. While for PCP, the factors of influence on sorption capacity were mainly CEC, Ca-binding-FA, and Ca-binding-HA. [ABSTRACT FROM AUTHOR]

The partitioning behavior of pentachlorophenol (PCP) in five sediments was studied using equilibrium sorption experiments and multiple cycles of sorption and desorption experiments. The results of the equilibrium sorption experiments showed that the isotherms of PCP on five sediments were linear and the partitioning coefficients (Kd) were proportional to the organic carbon content of the sediments. The average organic carbon content normalized partitioning coefficient (logKoc) of five sediments was 2.83±1.48. In multiple cycles of sorption and desorption experiments, the five sediments were found to exhibit statistically significant sorption–desorption hysteresis, and the hysteresis indices (HI) varied over a wide range (0.72–11.82). Correlations between the HI value and the percentage of lipid in the total organic matter in the sediment indicated that lipid was the main fraction to affect the hysteresis phenomenon, i.e., the higher the lipid percentage the greater the HI value. The hysteresis phenomenon was mostly caused by irreversible sorption of PCP on lipids, including entrapment by lipids, which induced the slow desorption rate from the sediment. Because of hysteresis in the sorption and desorption, the PCP ecological toxicity would be lower than expected. [Copyright &y& Elsevier]

Spatial distribution of heavy metals, arsenic and organic matter in recent sediments In the Hangzhou section of the Grand Canal and their relationships were analyzed. The results showed that the concentrations of heavy metals and organic matters varied widely along the canal, and the average geological accumulation factors decreased in the following orders: organic carbon (2.6). zinc (2.1). cadmium (2.0), copper (1.5), lead (1.1.), nitrogen (0.9), mercury (0.8), phosphorus (0.4), arsenic (0.2) and chromium (0). Content of heavy metals and organic carbon in the top 10 cm layer were lower than that of lower layers, except for mercury and organic carbon in the S9 section. Contents of organic carbon in the top 50 cm layer of the mud sediments are significantly higher than those underneath. In the bottom mud layer, there is a concentration peak of the pollutants. In the mud sediments of the canal, cadmium mainly occurred in the Fe and Mn oxide fraction, copper in the organic fraction, lead in the Fe and Mn oxide fraction, and zinc in the carbonate and the Fe and Mn oxide fraction. [ABSTRACT FROM AUTHOR]

Two new organocatalysts 3aand 3b, derived from l-leucine and (S)--amino alcohols that were prepared from l-valine, were designed and afforded the direct syn-aldol reactions of a wide scope of aldehydes with various ketones with an excellent diastereomeric ratio of up to >20/1 and enantioselectivities of up to 99% ee. [ABSTRACT FROM AUTHOR]

Five new d 8and d 10metal complexes, Pd(8-hq) 2( 1), [Ag(8-Hhq) 2]NO 3( 2), Ag(8-hq)(8-Hhq) ( 3), [(8-H 2hq) 2PdCl 4]·2H 2O ( 4), and Pt(8-hq)(tht)Cl ( 5) (tht = tetrahydrothiophene), all with a fluorogenic chelating agent, 8-hydroxyquinaldine (8-Hhq), have been synthesized and characterized. The aggregations of their photoactive metal centers through π−π stacking and hydrogen bonding interactions construct the interesting frameworks. The strong emissions of 1− 3and 5in solid states with orange, cyan, and green luminescences originating from metal··· metal and π−π interactions are assigned as metal to ligand charge transfer/metal–metal to ligand charge transfer/intraligand emissions. The solvent effects on their photophysical properties are examined, which exhibit a wide range of strong luminescences in the different organic solvents. In addition, time-dependent density functional theory calculations using the B3LYP functional on 1are in good agreement with the experiments. Thermogravimetric analyses and UV/vis spectra with composition of certain simulated results are also reported. [ABSTRACT FROM AUTHOR]

The rational selection of the templating agents or structure-directing agents (SDAs) is important for the designed synthesis of open-framework materials with specific channel structures. By utilizing organic amines that are predicted by computer simulations as the templates or SDAs, such as cyclohexylamine (CHA), cyclopentylamine (CPA), and n-propylamine, three new open-framework zinc phosphites, including (C 6H 14N) 2[Zn 3(HPO 3) 4] (ZnHPO-CJ2), (C 5H 12N) 2[Zn 3(HPO 3) 4] (ZnHPO-CJ3), and (C 3H 10N) 2[Zn 3(HPO 3) 4] (ZnHPO-CJ4), have been hydrothermally prepared with desired extra-large 24-ring channels analogous to (C 4NH 12) 2[Zn 3(HPO 3) 4] (ZnHPO-CJ1). Their structures are characterized by single-crystal and powder X-ray diffraction, inductively coupled plasma (ICP), IR, and thermogravimetric analyses. These organic amines predicted based on nonbonding interactions of host–guest show good matching in the space and charge density with the host inorganic framework. As with ZnHPO-CJ1 and other known extra-large micropore materials with high framework charge density, the 24-rings of these compounds are assembled around multiple small amines, exemplifying the cooperative templating mechanism of multiple small organic cations in the formation of extra-large micropore open-framework materials. This work demonstrates a useful strategy toward the template-designed synthesis of microporous materials with extra-large micropores. [ABSTRACT FROM AUTHOR]

In the molecule of the title compound, C16H18O, the dihedral angle between the rings is 70.61 (3)°. In the crystal structure, intermolecular O—H...O hydrogen bonds link the molecules into chains, and may be effective in the stabilization of the structure. [ABSTRACT FROM AUTHOR]