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排序方式: 共有87条查询结果,搜索用时 15 毫秒
1.
P Bernardi F Pecoraro L Bastagli C Adani M Cavazza D Cervellati M Rossetti 《Bollettino della Società italiana di biologia sperimentale》1979,55(21):2228-2234
The increase of gastric mucosal defensive reachons under linoleic acid loading (20 mg/kg i.m. x 2 x 10 die; 140-220 mg/kg per os x 2 x 15 die), was evaluated in hydrocortisone treated rats (10 mg/kg i.m. x 2 x 10 die) and in rats stressed by immobilisation at a low temperature (at 4 degrees for 1 hour). The incidence and extent of gastric lesions were recorded, in both samples treated differentialy, and in control groups. Although the results were not similarly significant in every case, the capacity of the linoleic acid administrations in limiting the gastric mucose injury was evident. This protective capacity is not dependent on the lesive agent. 相似文献
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Manolis Matzapetakis Debdip Ghosh Tsu-Chien Weng James E. Penner-Hahn Vincent L. Pecoraro 《Journal of biological inorganic chemistry》2006,11(7):876-890
Herein, we evaluate the binding of Pb(II) and Bi(III) to cysteine-substituted versions of the TRI peptides [AcG-(LKALEEK)4G-NH2] which have previously been shown to bind Hg(II) and Cd(II) in unusual geometries as compared with small-molecule thiol ligands in aqueous solutions. Studies of Pb(II) and Bi(III) with the peptides give rise to complexes consistent with the metal ions bound to three sulfur atoms with M–S distances of 2.63 and 2.54 Å, respectively. Competition experiments between the metal ions Pb(II), Cd(II), Hg(II) and Bi(III) for the peptides show that Hg(II) has the highest affinity, owing to the initial formation of the extremely strong HgS2 bond. Cd(II) and Pb(II) have comparable binding affinities at pH > 8, while Bi(III) displays the weakest affinity, following the model, M(II) + (TRI LXC)3 3? → M(II)(TRI LXC)3 ?. While the relevant equilibria for Hg(II) binding to the TRI peptides corresponds to a strong first step forming Hg(TRI LXC)2(HTRI LXC), followed by a single deprotonation to give Hg(TRI LXC)3 ?, the binding of Cd(II) and Pb(II) is consistent with initial formation of M(II)(TRI LXC)(HTRI LXC)2 + at pH < 5 followed by a two-proton dissociation step (pK a2) yielding M(II)(TRI LXC)3 ?. Pb(II)(TRI LXC)(HTRI LXC)2 + converts to Pb(II)(TRI LXC)3 ? at slightly lower pH values than the corresponding Cd(II)–peptide complexes. In addition, Pb(II) displays a lower pK a of binding to the “d”-substituted peptide, (TRI L12C, pK a2 = 12.0) compared with the “a”-substituted peptide, (TRI L16C, pK a2 = 12.6), the reverse of the order seen for Hg(II) and Cd(II). Pb(II) also showed a stronger binding affinity for TRI L12C (K bind = 3.2 × 107 M?1) compared with that with TRI L16C (K bind = 1.2 × 107 M?1) at pH > 8. 相似文献
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Developments in manganese biochemistry have centered on the discovery of new manganese enzymes, X-ray analysis of binuclear manganese enzymes, and the discovery of new spectroscopic signatures for the oxygen-evolving complex. Despite these gains, many questions regarding the structure, composition and redox state of the oxygen-evolving complex remain unanswered. 相似文献
5.
Sanna D Pecoraro VL Micera G Garribba E 《Journal of biological inorganic chemistry》2012,17(5):773-790
Density functional theory (DFT) methods were used to simulate the environment of vanadium in several V proteins, such as vanadyl-substituted carboxypeptidase (sites A and B), vanadyl-substituted chloroplast F(1)-ATPase (CF(1); site 3), the reduced inactive form of vanadium bromoperoxidase (VBrPO; low- and high-pH sites), and vanadyl-substituted imidazole glycerol phosphate dehydratase (IGPD; sites α, β, and γ). Structural, electron paramagnetic resonance, and electron spin echo envelope modulation parameters were calculated and compared with the experimental values. All the simulations were performed in water within the framework of the polarizable continuum model. The angular dependence of [Formula: see text] and [Formula: see text] on the dihedral angle θ between the V=O and N-C bonds and on the angle φ between the V=O and V-N bonds, where N is the coordinated aromatic nitrogen atom, was also found. From the results it emerges that it is possible to model the active site of a vanadium protein through DFT methods and determine its structure through the comparison between the calculated and experimental spectroscopic parameters. The calculations confirm that the donor sets of sites B and A of vanadyl-substituted carboxypeptidase are [[Formula: see text], H(2)O, H(2)O, H(2)O] and [N(His)(||), N(His)(⊥), [Formula: see text], H(2)O], and that the donor set of site 3 of CF(1)-ATPase is [[Formula: see text], OH(Thr), H(2)O, H(2)O, [Formula: see text]]. For VBrPO, the coordination modes [N(His)(||), N(His)(∠), OH(Ser), H(2)O, H(2)O(ax)] for the low-pH site and [N(His)(||), N(His)(∠), OH(Ser), OH(-), H(2)O(ax)] or [N(His)(||), N(His)(∠), [Formula: see text], H(2)O] for the high-pH site, with an imidazole ring of histidine strongly displaced from the equatorial plane, can be proposed. Finally, for sites α, β, and γ of IGPD, the subsequent deprotonation of one, two, and three imidazole rings of histidine and the participation of a carboxylate group of a glutamate residue ([N(His)(||), [Formula: see text], H(2)O, H(2)O], [N(His)(||), N(His)(||), [Formula: see text], H(2)O], and [N(His)(||), N(His)(||), [Formula: see text], OH(-), [Formula: see text]], respectively) seems to be the most plausible hypothesis. 相似文献
6.
Arne Holst-Jensen Yves Bertheau Marc de Loose Lutz Grohmann Sandrine Hamels Lotte Hougs Dany Morisset Sven Pecoraro Maria Pla Marc Van den Bulcke Doerte Wulff 《Biotechnology advances》2012
Genetically modified plants, in the following referred to as genetically modified organisms or GMOs, have been commercially grown for almost two decades. In 2010 approximately 10% of the total global crop acreage was planted with GMOs (James, 2011). More than 30 countries have been growing commercial GMOs, and many more have performed field trials. Although the majority of commercial GMOs both in terms of acreage and specific events belong to the four species: soybean, maize, cotton and rapeseed, there are another 20 + species where GMOs are commercialized or in the pipeline for commercialization. The number of GMOs cultivated in field trials or for commercial production has constantly increased during this time period. So have the number of species, the number of countries involved, the diversity of novel (added) genetic elements and the global trade. All of these factors contribute to the increasing complexity of detecting and correctly identifying GMO derived material. Many jurisdictions, including the European Union (EU), legally distinguish between authorized (and therefore legal) and un-authorized (and therefore illegal) GMOs. Information about the developments, field trials, authorizations, cultivation, trade and observations made in the official GMO control laboratories in different countries around the world is often limited, despite several attempts such as the OECD BioTrack for voluntary dissemination of data. This lack of information inevitably makes it challenging to detect and identify GMOs, especially the un-authorized GMOs. The present paper reviews the state of the art technologies and approaches in light of coverage, practicability, sensitivity and limitations. Emphasis is put on exemplifying practical detection of un-authorized GMOs. Although this paper has a European (EU) bias when examples are given, the contents have global relevance. 相似文献
7.
Meelich K Zaleski CM Pecoraro VL 《Philosophical transactions of the Royal Society of London. Series B, Biological sciences》2008,363(1494):1271-9; discussion 1279-81
The molecular oxygen produced in photosynthesis is generated via water oxidation at a manganese-calcium cluster called the oxygen-evolving complex (OEC). While studies in biophysics, biochemistry, and structural and molecular biology are well known to provide deeper insight into the structure and workings of this system, it is often less appreciated that biomimetic modelling provides the foundation for interpreting photosynthetic reactions. The synthesis and characterization of small model complexes, which either mimic structural features of the OEC or are capable of providing insight into the mechanism of O2 evolution, have become a vital contributor to this scientific field. Our group has contributed to these findings in recent years through synthesis of model complexes, spectroscopic characterization of these systems and probing the reactivity in the context of water oxidation. In this article we describe how models have made significant contributions ranging from understanding the structure of the water-oxidation centre (e.g. contributions to defining a tetrameric Mn3Ca-cluster with a dangler Mn) to the ability to discriminate between different mechanistic proposals (e.g. showing that the Babcock scheme for water oxidation is unlikely). 相似文献
8.
Background
Population movements along the Thailand-Cambodia border, particularly among highly mobile and hard-to-access migrant groups from Cambodia and Myanmar, are assumed to play a key role in the spread of artemisinin resistance. Data on treatment-seeking behaviours, knowledge and perceptions about malaria, and use of preventive measures is lacking as characteristics of this population prevent them from being represented in routine surveillance and the lack of a sampling frame makes reliable surveys challenging.Methods
A survey of migrant populations from Cambodia and Myanmar was implemented in five selected rural locations in Thailand along the Thai-Cambodian border using respondent driven sampling (RDS) to determine demographic characteristics of the population, migratory patterns, knowledge about malaria, and health-care -seeking behaviours.Results
The majority of migrants from Myanmar are long-term residents (98%) with no plans to move back to Myanmar, understand spoken Thai (77%) and can therefore benefit from health messages in Thai, have Thai health insurance (99%) and accessed public health services in Thailand (63%) for their last illness. In comparison, the majority of Cambodian migrants are short-term (72%). Of the short-term Cambodian migrants, 92% work in agriculture, 18% speak Thai, 3.4% have Thai health insurance, and the majority returned to Cambodia for treatment (45%), self-treated (11%), or did not seek treatment for their last illness (27%).Conclusion
Most highly mobile migrants along the Thai-Cambodia border are not accessing health messages or health treatment in Thailand, increasing their risk of malaria and facilitating the spread of potentially resistant Plasmodium falciparum as they return to Cambodia to seek treatment. Reaching out to highly mobile migrants with health messaging they can understand and malaria diagnosis and treatment services they can access is imperative in the effort to contain the spread of artemisinin-resistant P. falciparum. 相似文献9.
Intercellular communication in the rat anterior pituitary gland: an in vivo and in vitro study 总被引:2,自引:1,他引:2 下载免费PDF全文
The concept of "stimulus-secretion coupling" suggested by Douglas and co-workers to explain the events related to monamine discharge by the adrenal medulla (5, 7) may be applied to other endocrine tissues, such as adrenal cortex (36), pancreatic islets (4), and magnocellular hypothalamic neurons (6), which exhibit a similar ion-dependent process of hormone elaboration. In addition, they share another feature, that of joining neighbor cells via membrane junctions (12, 26, and Fletcher, unpublished observation). Given this, and the reports that hormone secretion by the pars distalis also involves a secretagogue-induced decrease in membrane bioelectric potential accompanied by a rise in cellular [Ca++] (27, 34, 41), it was appropriate to test the possibility that cells of the anterior pituitary gland are united by junctions. 相似文献
10.