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61.
Earthquake risks are attracting increased attention as a result of recent catastrophic events such as the Wenchuan earthquake in China. This article aims to select, tailor, and develop loss modeling methods for catastrophic insurance. We review the state-of-the-art approaches in modeling catastrophe losses for catastrophe bonds’ modeling and pricing. The methods are applied to the 1966–2008 losses resulted from the earthquakes in China. Various error measures are proposed for validating catastrophe modeling. Results suggest that the double exponential jump-diffusion model fits the data well. 相似文献
62.
Rui Ma 《Biochemical and biophysical research communications》2010,394(2):330-334
An increasing number of analgesic peptides have been found in the tail toxicyst, but there has been little research into their analgesic domains. Where are the analgesic domains in a conservative βαββ topology conformation of the analgesic peptides? We have carried out research to address this question. On account of the importance of disulfide bonds in the study of protein structure, the conformational stability, catalytic activity and folding, and site-directed mutagenesis in disulfide bridges have been used to look for the analgesic domain in a mature antitumor-analgesic peptide from the venom of the Chinese scorpion Buthus martensii Karsch (BmK AGAP). The mouse-twisting assay was used to examine the analgesic activity of 12 mutants, in which two mutants (C22S, C46S) and (C16S, C36S), exhibited lower relative activity. Following the conformational analysis, one domain, called the “core domain”, was found to be the key to the analgesic activity. 相似文献
63.
Zhou XR Robert SS Petrie JR Frampton DM Mansour MP Blackburn SI Nichols PD Green AG Singh SP 《Phytochemistry》2007,68(6):785-796
The marine microalga Pavlova salina produces lipids containing approximately 50% omega-3 long chain polyunsaturated fatty acids (LC-PUFA) such as docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA). Three cDNA sequences, designated PsD4Des, PsD5Des, PsD8Des, were isolated from P. salina and shown to encode three front-end desaturases with Delta4, Delta5 and Delta8 specificity, respectively. Southern analysis indicated that the P. salina genome contained single copies of all three front-end fatty acid desaturase genes. When grown at three different temperatures, analysis of fatty acid profiles indicated P. salina desaturation conversions occurred with greater than 95% efficiency. Real-Time PCR revealed that expression of PsD8Des was higher than for the other two genes under normal growth conditions, while PsD5Des had the lowest expression level. The deduced amino acid sequences from all three genes contained three conserved histidine boxes and a cytochrome b(5) domain. Sequence alignment showed that the three genes were homologous to corresponding desaturases from other microalgae and fungi. The predicted activities of these three front-end desaturases leading to the synthesis of LC-PUFA were also confirmed in yeast and in higher plants. 相似文献
64.
Disulfide reductases of host-colonising bacteria are involved in the expression of virulence factors, resistance to drugs,
and elimination of toxic compounds. Large-scale genome analyses of 281 prokaryotes identified CXXC and CXXC-derived motifs
in each microorganism. The total number of these motifs showed correlations with genome size and oxygen tolerance of the prokaryotes.
Specific bioinformatic analyses served to identify putative disulfide reductases in the Campylobacterales Campylobacter jejuni, Helicobacter pylori, Wolinella succinogenes and Arcobacter butzleri which colonise the gastrointestinal tract of higher animals. Three filters applied to the genomes of these species yielded
35, 25, 28 and 34 genes, respectively, encoding proteins with the characteristics of disulfide reductases. Ten proteins were
common to the four species, including four belonging to the thioredoxin system. The presence of thioredoxin reductase activities
was detected in the four bacterial species by observing dithiobis-2-nitrobenzoic acid reduction with β-nicotinamide adenine
dinucleotide phosphate as cofactor. Phylogenetic analyses of the thioredoxin reductases TrxB1 and TrxB2 of the four Campylobacterales were performed. Their TrxB1 proteins were more closely related to those of Firmicutes than to the corresponding proteins of other Proteobacteria. The
Campylobacterales TrxB2 proteins were closer to glutathione reductases of other organisms than to their respective TrxB1 proteins. The phylogenetic features of the Campylobacterales thioredoxin reductases suggested a special role for these enzymes
in the physiology of these bacteria.
Electronic Supplementary Material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
65.
Tiddo J. Mooibroek 《Inorganica chimica acta》2007,360(1):381-404
Supramolecular chemistry is a topical field of contemporary research whose current tremendous progress is aided by the development of crystal structure determination and theoretical studies, both resulting from considerable advances in computer science. Consequently, supramolecular interactions are more easily appraised, and even the weakest ones, such as anion-π contacts, can nowadays be investigated. The present paper gives an account on the different types of interactions encountered by the supramolecular chemist, with an emphasis on the remarkable 1,3,5-triazine ring which can experience all of them, namely coordination bonds, hydrogen bonding, electrostatic and charge-transfer attractions, and aromatic-stacking interactions. Indeed, a thorough search in the Cambridge Structure Database clearly shows that this simple 1,3,5-triazine synthon can be involved in all the categories of supramolecular interactions aforementioned. 相似文献
66.
Marina V. Kirillova 《Inorganica chimica acta》2007,360(2):506-512
The heteronuclear water-soluble and air-stable compounds [M(H2O)5M′(dipic)2] · mH2O (M/M′ = CuII/CoII (1), CuII/NiII (2), CuII/ZnII (3), ZnII/CoII (4), NiII/CoII (5), m = 2-3; H2dipic = dipicolinic acid) have been prepared by self-assembly synthesis in aqueous solution at room temperature, and characterized by IR, UV-Vis and atomic absorption spectroscopies, elemental and X-ray diffraction single crystal (for 1 and 2) analyses. 1-5 represent the first examples of heteronuclear dipicolinate compounds with 3d metals. Extensive H-bonding interactions involving all aqua ligands, dipicolinate oxygens and lattice water molecules further stabilize the dimetallic units by linking them to form three-dimensional polymeric networks. 相似文献
67.
Keratinases degrade feather in presence of a suitable reducing agent. Here we have demonstrated that conventional serine and
cysteine proteases (subtilsin, chymotrypsin and papain) which selectively cleave proteins at the hydrophobic P1 residues also
degrade feathers in presence of a suitable reducing agent in the form of live cells or chemical reductants. Further, trypsin
and pepsin were also shown to degrade feather after cleaving hydrophobic residues of feathers following 2 h pre-treatment
by any of the proteases. 相似文献
68.
Silk JB 《Philosophical transactions of the Royal Society of London. Series B, Biological sciences》2007,362(1480):539-559
According to behavioural ecology theory, sociality evolves when the net benefits of close association with conspecifics exceed the costs. The nature and relative magnitude of the benefits and costs of sociality are expected to vary across species and habitats. When sociality is favoured, animals may form groups that range from small pair-bonded units to huge aggregations. The size and composition of social groups have diverse effects on morphology and behaviour, ranging from the extent of sexual dimorphism to brain size, and the structure of social relationships. This general argument implies that sociality has fitness consequences for individuals. However, for most mammalian species, especially long-lived animals like primates, there are sizable gaps in the chain of evidence that links sociality and social bonds to fitness outcomes. These gaps reflect the difficulty of quantifying the cumulative effects of behavioural interactions on fitness and the lack of information about the nature of social relationships among individuals in most taxa. Here, I review what is known about the reproductive consequences of sociality for mammals. 相似文献
69.
Mahapatra A Mativandlela SP Binneman B Fourie PB Hamilton CJ Meyer JJ van der Kooy F Houghton P Lall N 《Bioorganic & medicinal chemistry》2007,15(24):7638-7646
The naphthoquinone 7-methyljuglone (5-hydroxy-7-methyl-1,4-naphthoquinone) has previously been isolated and identified as an active component of root extracts of Euclea natalensis which displays antitubercular activity. Herein, a series of synthetic and plant-derived naphthoquinone derivates of the 7-methyljuglone scaffold have been prepared and evaluated for antibacterial activity against Mycobacterium tuberculosis. Several of these compounds have been shown to operate as subversive substrates with mycothiol disulfide reductase. The absence of a direct correlation between antitubercular activity and subversive substrate efficiency with mycothiol disulfide reductase, might be a consequence of their non-specific reactivity with multiple biological targets (e.g. other disulfide reductases). 相似文献
70.
Graham LD Pilling PA Eaton RE Gorman JJ Braybrook C Hannan GN Pawlak-Skrzecz A Noyce L Lovrecz GO Lu L Hill RJ 《Protein expression and purification》2007,53(2):309-324
Cloned EcR and USP cDNAs encoding the ecdysone receptors of four insect pests (Lucilia cuprina, Myzus persicae, Bemisia tabaci, Helicoverpa armigera) were manipulated to allow the co-expression of their ligand binding domains (LBDs) in insect cells using a baculovirus vector. Recombinant DE/F segment pairs (and additionally, for H. armigera, an E/F segment pair) from the EcR and USP proteins associated spontaneously with high affinity to form heterodimers that avidly bound an ecdysteroid ligand. This shows that neither ligand nor D-regions are essential for the formation of tightly associated and functional LBD heterodimers. Expression levels ranged up to 16.6mg of functional apo-LBD (i.e., unliganded LBD) heterodimer per liter of recombinant insect cell culture. Each recombinant heterodimer was affinity-purified via an oligo-histidine tag at the N-terminus of the EcR subunit, and could be purified further by ion exchange and/or gel filtration chromatography. The apo-LBD heterodimers appeared to be more easily inactivated than their ligand-containing counterparts: after purification, populations of the former were <40% active, whereas for the latter >70% could be obtained as the ligand-LBD heterodimer complex. Interestingly, we found that the amount of ligand bound by recombinant LBD heterodimer preparations could be enhanced by the non-denaturing detergent CHAPS (3-[(3-cholamidopropyl)dimethyl-ammonio]-1-propanesulfonate). Purity, integrity, size and charge data are reported for the recombinant proteins under native and denaturing conditions. Certain intra- and intermolecular disulfide bonds were observed to form in the absence of reducing agents, and thiol-specific alkylation was shown to suppress this phenomenon but to introduce microheterogeneity. 相似文献