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31.
Interaction of the neuropeptide met-enkephalin with zwitterionic and negatively charged bicelles as viewed by 31P and 2H solid-state NMR 下载免费PDF全文
The interaction of the neuropeptide methionine-enkephalin (Menk) with bicelles was investigated by solid-state NMR. Bicelles composed of dimyristoylphosphatidylcholine (DMPC) and dicaproylphosphatidylcholine (DCPC) were modified to investigate the effect of the lipid headgroup and electrostatic charges on the association with Menk. A total of 10 mol % of DMPC was replaced by zwitterionic phosphatidylethanolamine (DMPE), anionic phosphatidylglycerol (DMPG), or phosphatidylserine (DMPS). The preparation of DMPE-doped bicelles (Bic/PE) is reported for the first time. The (31)P and (2)H NMR results revealed changes in the lipid dynamics when Menk interacts with the bicellar systems. (2)H NMR experiments showed a disordering effect of Menk on the lipid chains in all the bicelles except Bic/PG, whereas the study of the choline headgroups indicated a decreased order of the lipids only in Bic/PE and Bic/PG. Our results suggest that the insertion depth of Menk into bicelles is modulated by their composition, more specifically by the balance between hydrophobic and electrostatic interactions. Menk would be buried at the lipid polar/apolar interface, the depth of penetration into the hydrophobic membrane core following the scaling Bic > Bic/PE > Bic/PS at the slightly acidic pH used in this study. The peptide would not insert into the bilayer core of Bic/PG and would rather remain at the surface. 相似文献
32.
Dirmeier R O'Brien KM Engle M Dodd A Spears E Poyton RO 《The Journal of biological chemistry》2002,277(38):34773-34784
The mitochondrial respiratory chain is required for the induction of some yeast hypoxic nuclear genes. Because the respiratory chain produces reactive oxygen species (ROS), which can mediate intracellular signal cascades, we addressed the possibility that ROS are involved in hypoxic gene induction. Recent studies with mammalian cells have produced conflicting results concerning this question. These studies have relied almost exclusively on fluorescent dyes to measure ROS levels. Insofar as ROS are very reactive and inherently unstable, a more reliable method for measuring changes in their intracellular levels is to measure their damage (e.g. the accumulation of 8-hydroxy-2'-deoxyguanosine (8-OH-dG) in DNA, and oxidative protein carbonylation) or to measure the expression of an oxidative stress-induced gene, e.g. SOD1. Here we used these approaches as well as a fluorescent dye, carboxy-H(2)-dichloro-dihydrofluorescein diacetate (carboxy-H(2)-DCFDA), to determine whether ROS levels change in yeast cells exposed to anoxia. These studies reveal that the level of mitochondrial and cytosolic protein carbonylation, the level of 8-OH-dG in mitochondrial and nuclear DNA, and the expression of SOD1 all increase transiently during a shift to anoxia. These studies also reveal that carboxy-H(2)-DCFDA is an unreliable reporter of ROS levels in yeast cells shifted to anoxia. By using two-dimensional electrophoresis and mass spectrometry (matrix-assisted laser desorption ionization time-of-flight), we have found that specific proteins become carbonylated during a shift to anoxia and that some of these proteins are the same proteins that become carbonylated during peroxidative stress. The mitochondrial respiratory chain is responsible for much of this carbonylation. Together, these findings indicate that yeast cells exposed to anoxia experience transient oxidative stress and raise the possibility that this initiates the induction of hypoxic genes. 相似文献
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34.
Mayra Chamlian Erick L. Bastos Ceres Maciel Margareth L. Capurro Antonio Miranda Adriana F. Silva Marcelo Der T. Torres Vani X. Oliveira Jr 《Journal of peptide science》2013,19(9):575-580
Controlling the dissemination of malaria requires the development of new drugs against its etiological agent, a protozoan of the Plasmodium genus. Angiotensin II and its analog peptides exhibit activity against the development of immature and mature sporozoites of Plasmodium gallinaceum. In this study, we report the synthesis and characterization of angiotensin II linear and cyclic analogs with anti‐plasmodium activity. The peptides were synthesized by a conventional solid‐phase method on Merrifield's resin using the t‐Boc strategy, purified by RP‐HPLC and characterized by liquid chromatography/ESI (+) MS (LC‐ESI(+)/MS), amino acid analysis, and capillary electrophoresis. Anti‐plasmodium activity was measured in vitro by fluorescence microscopy using propidium iodine uptake as an indicator of cellular damage. The activities of the linear and cyclic peptides are not significantly different (p < 0.05). Kinetics studies indicate that the effects of these peptides on plasmodium viability overtime exhibit a sigmoidal profile and that the system stabilizes after a period of 1 h for all peptides examined. The results were rationalized by partial least‐square analysis, assessing the position‐wise contribution of each amino acid. The highest contribution of polar amino acids and a Lys residue proximal to the C‐terminus, as well as that of hydrophobic amino acids in the N‐terminus, suggests that the mechanism underlying the anti‐malarial activity of these peptides is attributed to its amphiphilic character. Copyright © 2013 European Peptide Society and John Wiley & Sons, Ltd. 相似文献
35.
Alexandro Bonifaz Berenice Córdoba-García Tania Simancas-Llanos Marco A. Hernández Erick Martínez-Herrera Andrés Tirado-Sánchez 《Revista iberoamericana de micología》2019,36(1):30-33
Background
Nannizzia nana is a zoophilic dermatophyte that affects animals like pigs, boars and, exceptionally, humans, in whom it causes tinea capitis, as well as tinea corporis and onychomycosis.Case report
Case 1. A previously healthy 8 year-old boy presented to our clinic with a 1-month evolution dermatosis that affected scalp, developing a pseudoalopecic tumor lesion with abundant seropurulent material. The patient had worked in a pig farm. Case 2. A previously healthy 6 year-old girl, sister of the aforementioned child, presented to our clinic with a dermatosis characterized by multiple erythematous-scaly plaques that affected her face, trunk and arms. N. nana was the fungus isolated on culture in both cases. The children were treated with oral griseofulvin and topical ketoconazole that led to clinical and mycological cures.Conclusions
N. nana dermatophytosis, although being rare in humans, can be treated as other cases of dermatophytosis. 相似文献36.
Mehdy Ratajczak Emilie Laroche Thierry Berthe Olivier Clermont Barbara Pawlak Erick Denamur Fabienne Petit 《BMC microbiology》2010,10(1):222
Background
Escherichia coli is a commensal bacterium of the gastro-intestinal tract of human and vertebrate animals, although the aquatic environment could be a secondary habitat. The aim of this study was to investigate the effect of hydrological conditions on the structure of the E. coli population in the water of a creek on a small rural watershed in France composed of pasture and with human occupation. 相似文献37.
Plant neighbor identity influences plant biochemistry and physiology related to defense 总被引:1,自引:0,他引:1
Amanda K Broz Corey D Broeckling Clelia De-la-Peña Matthew R Lewis Erick Greene Ragan M Callaway Lloyd W Sumner Jorge M Vivanco 《BMC plant biology》2010,10(1):115
Background
Chemical and biological processes dictate an individual organism's ability to recognize and respond to other organisms. A small but growing body of evidence suggests that plants may be capable of recognizing and responding to neighboring plants in a species specific fashion. Here we tested whether or not individuals of the invasive exotic weed, Centaurea maculosa, would modulate their defensive strategy in response to different plant neighbors. 相似文献38.
Strauss E 《Nature chemical biology》2010,6(12):873-875
Variations between single members of a bacterial population can lead to antibiotic resistance that is not gene based. The future of effective infectious disease management might depend on a better understanding of this phenomenon and the potential to manipulate both it and microbial population dynamics in general. 相似文献
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40.
Bonavita-Cougourdan A Provost E Riviere G Bagneres AG Dusticier G 《Journal of insect physiology》2004,50(4):285-293
The purpose of this study was to compare cuticular hydrocarbon profiles of slave-making Polyergus rufescens ants reared alone or with their Formica rufibarbis slaves. Chemical analyses showed that due to the close contacts occurring when the Formica were tending the Polyergus, the synthesis of the cuticular hydrocarbons carried by the slaves was enhanced in the slave-makers. The postpharyngeal hydrocarbon levels increased during the first 15 days of life, whether or not the Polyergus were exposed to Formica. Our findings suggest that Polyergus is able to secrete all components of their cuticular hydrocarbon blend and that none are acquired through contact with Formica. In addition to presenting our experimental evidence, several hypotheses are proposed to explain the synthesis and regulation of hydrocarbon blends borne when these two species cohabitate within a single colony. 相似文献