The neisserial porins are the major protein components of the outer membrane of the pathogenic Neisseria (N. meningitidis and N. gonorrhoeae). They have been shown to be able to enhance the immune response to poorly immunogenic substances (e.g., polysaccharides, peptides, glycolipids, etc.). To explore the basis of their potent adjuvant activity, the effect of the neisserial porins on T-B cell interactions and T cell costimulation was examined. Neisserial porins increased the surface expression of the costimulatory ligand B7-2 (CD86) but did not affect the expression of B7-1 (CD80). In addition, incubation with the neisserial porins increased the T lymphocyte costimulatory ability of B lymphocytes, which was inhibited by anti-B7-2 but not anti-B7-1 monoclonal antibodies. Upregulation of B7-2 on the surface of B lymphocytes may be the mechanism behind the immunopotentiating activity of neisserial porins. ...
TY - JOUR. T1 - Lipopolysaccharide-free Escherichia coli OmpF and Pseudomonas aeruginosa protein P porins are functionally active in lipid bilayer membranes. AU - Parr, T. R.. AU - Poole, K.. AU - Crockford, G. W.K.. AU - Hancock, R. E.W.. PY - 1986/1/1. Y1 - 1986/1/1. UR - http://www.scopus.com/inward/record.url?scp=0022466549&partnerID=8YFLogxK. U2 - 10.1128/jb.165.2.523-526.1986. DO - 10.1128/jb.165.2.523-526.1986. M3 - Article. C2 - 3003028. AN - SCOPUS:0022466549. VL - 165. SP - 523. EP - 526. JO - Journal of bacteriology. JF - Journal of bacteriology. SN - 0021-9193. IS - 2. ER - ...
The membrane assembly of outer membrane proteins is more complex than that of transmembrane helical proteins owing to the intervention of many charged and polar residues in the membrane. Accordingly, the predictive accuracy of transmembrane beta strands is considerably lower than that of transmembrane alpha helices. In this paper we develop a set of conformational parameters for membrane spanning beta strands. We formulate an algorithm to predict the transmembrane beta strands in the family of bacterial porins based on the conformational parameters and surrounding hydrophobicities of amino acid residues. A Fortran program has been developed which takes the amino acid sequence as the input file and gives the predicted transmembrane beta strand as output. The present method predicts at an accuracy level of 82% for all the bacterial porins considered.
The Tar chemoreceptor of Escherichia coli is a membrane-bound sensory protein that facilitates bacterial chemotaxis in response to aspartate. The EnvZ molecule has a membrane topology similar to Tar and is a putative osmosensor that is required for osmoregulation of the genes for the major outer membrane porin proteins, OmpF and OmpC. The cytoplasmic signaling domain of Tar was replaced with the carboxyl portion of EnvZ, and the resulting chimeric receptor activated transcription of the ompC gene in response to aspartate. The activation of ompC by the chimeric receptor was absolutely dependent on OmpR, a transcriptional activator for ompF and ompC. ...
Structural relatedness of enteric bacterial porins assessed with monoclonal antibodies to Salmonella typhimurium OmpD and OmpC.: The immunochemistry and structu
Outer membrane porin D is a protein family containing bacterial outer membrane porins which are involved in transport of cationic amino acids, peptides, antibiotics and other compounds. It was also described as having some serine protease activity. However many of these proteins are not peptidases and are classified as non-peptidase homologues as they either have been found experimentally to be without peptidase activity, or lack amino acid residues that are believed to be essential for the catalytic activity of peptidases in the S43 family. Yoshihara E, Yoneyama H, Ono T, Nakae T (June 1998). Identification of the catalytic triad of the protein D2 protease in Pseudomonas aeruginosa. Biochem. Biophys. Res. Commun. 247 (1): 142-5. doi:10.1006/bbrc.1998.8745. PMID 9636669. This article incorporates text from the public domain Pfam and InterPro ...
The proper functioning of proteins requires their correct localization to predetermined cellular locations. In the gram-negative bacterium Escherichia coliK-12, a special class of proteins known as porins (24) must be properly targeted and assembled in the outer membrane to form channels that facilitate the diffusion of hydrophilic solutes. The atomic structure showed that porins primarily consist of antiparallel β strands that are arranged in a pseudocyclic β-barrel structure, which encloses a water-filled channel (6, 29). On the periplasmic side, β strands are adjoined by short turns, whereas long loops provide connections on the medium-exposed side. Although the majority of loops are surface exposed, one or more loops fold inward thus restricting the channel. Surface-exposed loops are often utilized by bacteriophages as their receptors (35, 36, 37).. Outer membrane proteins (OMPs) are synthesized in the cytoplasm as precursors with an amino-terminal signal sequence that assists in exiting ...
Gram-negative bacteria are protected against external attack by an outer membrane. However, general diffusion porins located in this membrane allow the entry, by simple diffusion, of small molecules and, among them, antibiotics (beta-lactams and fluoroquinolones). Strains of bacteria resistant to beta-lactams have shown either a low porin density in the outer membrane, or some mutations at the level of porins affecting their internal size. Understand how antibiotics diffuse through these porins can help researcher to develop new antibiotics with an improved penetration especially when resistance becomes a serious problem for infectious disease. Recent experimental investigations pointed out how the diffusion of antibiotics through a porin is a molecular-based process: during diffusion the antibiotics interact strongly with the amino acids of the porin. Changing either the charge or the hydrophobicity of antibiotics the interaction strenght with the porin changes as well. Using a recent algorithm ...
A strain of Escherichia coli, selected on the basis of its resistance to colicin N, reveals distinct structural and functional alterations in unspecific OmpF porin. A single mutation [Gly-119--,Asp (G119D)] was identified in the internal loop L3 that contributes critically to the formation of the construction inside the lumen of the pore. X-ray structure analysis to a resolution of 3.0 A reveals a locally altered peptide backbone, with the side chain of residue Asp-119 protruding into the channel, causing the area of the constriction (7 x 11 A in the wild type) to be subdivided into two intercommunicating subcompartments of 3-4 A in diameter. The functional consequences of this structural modification consist of a reduction of the channel conductance by about one-third, of altered ion selectivity and voltage gating, and of a decrease of permeation rates of various sugars by factors of 2-12. The structural modification of the mutant protein affects neither the beta-barrel structure nor those ...
Recombinant P.IB (porB) protein (Tagged) is an Escherichia coli Full length protein 20 to 331 aa range, | 90% purity and validated in SDS-PAGE.
Sucrose-specific porin, molecular model. Porins are proteins that span cell membranes and act as a channel through which specific molecules can diffuse. - Stock Image F009/5873
The Escherichia coli porin OmpG, which acts as an efficient unspecific channel for mono-, di- and trisaccharides, has been purified and crystallized in two dimensions. Projection maps of two different crystal forms of OmpG at 6 A resolution show that the protein has a beta-barrel structure character …
1GFM: Structural and functional characterization of OmpF porin mutants selected for larger pore size. I. Crystallographic analysis.
The Mla pathway is hypothesized to be an ATP binding cassette transport system in Escherichia coli that maintains outer membrane asymmetry. Outer membrane proteins C (OmpC) and F (OmpF) have been shown to interact with MlaA, a key lipoprotein in the Mla pathway. ...
figure taken from the reference below). Murein means peptidoglycan cell wall and the cytoplasm denotes the inside of the cell. In this scenario, the double-membraned proto-bacteria (which has spend the last half-a-billion years or so evolving a well adjusted double membrane system) suddenly looses the outer membrane. A very simple genetic change would lead to a massively overgrown cell wall, which would rip the outer membrane away. The cell looses all its outer membrane porins, and signal systems, but in return gains a highly protective cell wall, which potentially allows it to survive in different niches. How these aspects are lost genetically is another matter, and the paper rather hand-waves away by saying that unused genes tend to get lost eventually. Which is true in bacteria, they have such a small genome they dont want it getting filled up with unnecessary genes, but I have a feeling genes tend to leave something behind. Even so, the question of where the now-unnecessary genes go is ...
1GFN: Structural and functional characterization of OmpF porin mutants selected for larger pore size. I. Crystallographic analysis.
1.B.68 The Putative Beta Barrel Porin-5 (BBP5) Superfamily. The BBP5 family consists of proteins homologous to the E. coli YfaZ protein. These proteins are predicted to be transmembrane beta barrel porins by the BOMP program, and they show significant sequence similarity to members of the large superfamily of porins. As of 8/2013, no member seems to have been functionally characterized. ...
Maltoporin allows permeation of long maltodextrin chains. It tightly binds the amphiphilic sugar, offering both hydrophobic interactions with a helical lane of aromatic residues and H bonds with ionic side chains. The minimum-energy path of maltohexaose translocation is obtained by the conjugate pea …
Phylogenetic analysis was utilized to investigate biological relationships (tissue tropism, disease presentation, and epidemiologic success), as evidenced by coevolution, among human strains ofChlamydia trachomatis. Nucleotide sequences ofomp1, the gene encoding the major outer membrane protein (MOMP) of C. trachomatis, were determined for 40 strains representing 11 serovars. These data were combined with availableomp1 sequences from GenBank for an analysis encompassing a total of 69 strains representing 17 serovars infecting humans. Phylogenetic analysis of the nucleotide and inferred amino acid sequences showed no evolutionary relationships among serovars that corresponded to biological or pathological phenotypes (tissue tropism, disease presentation, and epidemiologic success). In addition, no specific residues that may have evolved to play a role in determining biologically relevant characteristics of chlamydia, such as tissue specificity, disease presentation, and epidemiologic success, ...
A vaccine against C. trachomatis infection has proven difficult to develop. Early vaccine studies showed that whole inactivated bacterial cells administered intramuscularly were partially protective in human and primate trials. Primate vaccine trials and human experimental infection studies suggested that C. trachomatis immunity was in part strain specific, and the identification of MOMP as the strain-specific antigen of C. trachomatis quickly focused vaccine efforts on this protein. In general, use of MOMP or peptide epitopes derived from it as a vaccine has engendered variable or no protective immunity in a variety of animal model systems. The best results were observed when MOMP was used as a structurally intact molecule, suggesting that conformationally intact antigenic sites on the molecule are important for protective immunity.. We previously reported that MOMP DNA administered parenterally was also partially effective in inducing protective immunity against lung infection with MoPn. The ...
This entry represents both eukaryotic mitochondrial porins and Tom40 proteins.. Eukaryotic mitochondrial porins are voltage-dependent anion-selective channels (VDAC) that behave as general diffusion pores for small hydrophilic molecules [ (PUBMED:8031826) (PUBMED:1384178) (PUBMED:1689252) (PUBMED:2442148) ]. The channels adopt an open conformation at low or zero membrane potential and a closed conformation at potentials above 30-40 mV. The eukaryotic mitochondrial porins are beta-barrel proteins, composed of between 12 to 16 beta-strands that span the mitochondrial outer membrane. Yeast contains two members of this family (genes POR1 and POR2); vertebrates have at least three members (genes VDAC1, VDAC2 and VDAC3) [ (PUBMED:8812436) ]. They are related to the mitochondrial import receptor subunit Tom40 proteins, sharing a common evolutionary origin and structure [ (PUBMED:22178864) ]. Tom40 is a mitochondrion outer membrane protein and a component of the TOM (translocator of the outer ...
TY - JOUR. T1 - The role of mitochondrial porins and the permeability transition pore in learning and synaptic plasticity. AU - Weeber, Edwin J.. AU - Levy, Michael. AU - Sampson, Margaret J.. AU - Anflous, Keltoum. AU - Armstrong, Dawna L.. AU - Brown, Sarah E.. AU - David Sweatt, J.. AU - Craigen, William J.. PY - 2002/5/24. Y1 - 2002/5/24. N2 - Mitochondrial outer membrane permeability is conferred by a family of porin proteins. Mitochondrial porins conduct small molecules and constitute one component of the permeability transition pore that opens in response to apoptotic signals. Because mitochondrial porins have significant roles in diverse cellular processes including regulation of mitochondrial ATP and calcium flux, we sought to determine their importance in learning and synaptic plasticity in mice. We show that fear conditioning and spatial learning are disrupted in porin-deficient mice. Electrophysiological recordings of porin-deficient hippocampal slices reveal deficits in long and ...
In the current study, the construction of a toxR+ V. cholerae strain that expresses the ToxR-repressed porin OmpT in place of the ToxR-activated porin OmpU has allowed us to dissect the role these porins play in V. cholerae pathogenesis. Amazingly, merely substituting one outer membrane porin for another resulted in a number of attenuated pathogenic properties, including bile resistance, virulence factor expression, and intestinal colonization. ToxR-dependent regulation of outer membrane porins appears to have preceded the evolution of V. cholerae, because ToxR performs similar functions in other members of the Vibrionaceae (14, 17). However, these other bacteria do not have the additional regulatory factors TcpP and ToxT whose genes are located on the V. cholerae-specific pathogenicity island VPI (30). The recruitment of the ancestral ToxR protein into the virulence regulatory cascade involving recently acquired elements ties porin regulation to pathogenesis. We suggest that the contribution of ...
1.B.8 The Mitochondrial and Plastid Porin (MPP) Family Porins of the MPP family are found in eukaryotic organelles. The organelles include mitochondria of many eukaryotes as well as chloroplasts and plastids of plants. The best characterized members of the MPP family are the voltage-dependent anion-selective channel (VDAC) porins in the mitochondrial outer membrane. These porins have an estimated channel diameter of 2.5-3 nm. Topological models have been proposed in which VDAC consists of an N-terminal, globular α-helix and (1) 12 or 13 β-strands, (2) 16 β-strands or (3) 19 β-strands (now favored; see below) (Casadio et al., 2002). VDAC also appears to be present in plasma membranes (De Pinto et al., 2010). Prostacyclin receptor-mediated ATP release from ethrocytes requires VDAC (Sridharan et al., 2011). Phylogenetic analyses of eukaryotic VDAC proteins from diverse organisms have been reported (Wojtkowska et al. 2012). Over-oxidation of cysteines and succinylation of cysteines in VDACs has ...
Ertapenem is a potent carbapenem antibiotic for most clinical isolates of Klebsiella pneumoniae, with a typical MIC at which 90% of the isolates tested are inhibited of 0.03 to 0.06 μg/ml (6, 9), but occasional strains for which the MICs are ≥16 μg/ml have been detected (6, 7). In one such strain resistance was dependent on the presence of the plasmid-mediated extended-spectrum β-lactamase (ESBL) SHV-2 and additional host events presumably affecting ertapenem permeativity (7). Further studies were undertaken to elucidate the contribution of β-lactamase and host mutation to such exceptional resistance.. The K. pneumoniae strain for which the ertapenem MIC was 16 μg/ml was treated with ethidium bromide to cure the resident plasmid. The ertapenem MIC for the resulting strain, C2, was still elevated at l μg/ml, and the strain was found to be defective in expression of outer membrane porins OmpK35 and OmpK36 (10). To evaluate the influence of different β-lactamases on the ertapenem ...
Our results provide some important confirmation of theories regarding OprF structure and function. We have demonstrated that residues in the C-terminal domain of OprF are required for strong peptidoglycan association, as previously proposed (9). Expression of our truncated OprF mutants in E. coli orP. aeruginosa suggests that the first 154 to 163 aa of OprF are needed to produce a stable protein. This possibility is in strong agreement with the proposal that the first 160 aa of OprF form a β-barrel structure and suggests that residues critical to proper conformation of this domain are present between aa 154 and 163. The residues between aa 150 and 160 conform to the consensus sequence of the 16th C-terminal β strand of the porin superfamily (21, 22). Studies of other porins, such as E. coli PhoE, suggest that a phenylalanine residue in this terminal strand (equivalent to OprF residue 160) is critical for protein stability and proper folding (8). Our results may thus reflect deletion of such a ...
Shop Major outer membrane protein ELISA Kit, Recombinant Protein and Major outer membrane protein Antibody at MyBioSource. Custom ELISA Kit, Recombinant Protein and Antibody are available.
Connexins (Cxs) and pannexins (Panxs) are highly regulated large-pore channel-forming proteins that participate in cellular communication via small molecular exchange with the extracellular microenvironment, or in the case of connexins, directly between cells. in Cx40?/? mice was further exaggerated in double knockout mice. Thus, while gestation and gross development were conserved in Cx40?/?Panx1?/? mice, they exhibit cardiac hypertrophy, hypertension, and impaired endothelial-mediated vasodilation that phenocopies Cx40?/? mice. Nevertheless, the augmented renin homeostasis observed in the double knockout mice suggests that both Cx40 and Panx1 may play an integrative role. [3C5]. Conversely, the most well-understood pannexin, pannexin1 (Panx1), has been demonstrated to form large-pore membrane channels, which facilitate autocrine/paracrine-mediated signaling via the release of purine nucleotides, most notably ATP [6]. Within the mammalian cardiovascular system (cardiac tissue and peripheral ...
As we compare the condition of the world to-day with its condition at any former period, we find a marked differ- ence in the sentiments of the masses. The spirit of inde- pendence is now abroad, and men are not so easily blind- folded, deceived and led by rulers and politicians, and therefore they will not submit to the yokes of former days. This change of public sentiment has not been a gradual one from the very beginning of mans effort to govern L t pi- self, but clearly marked only as far back as the sixteenth century ; and its progress has been most rapid within the last fifty years. This change, therefore, is not the result of the experience of past ages, but is the natural result of the recent increase and general diffusion of knowledge among the masses of mankind. The preparation for this general diffusion of knowledge began with the invention of printing, about 1440 A. D., and the consequent multiplica- tion of books and news periodicals. The influence of this invention in the general ...
2017. Trebosc, V. et al. Reversion of Antibiotic Resistance in Mycobacterium tubercolosis by spiroisoxazoline SMARt-420″. Science 2017. Mar 2017 Vol. 355, Issue 6330, pp. 1206-1211 doi: 10.1126/science.aag1006. A. Gilardi, S.P. Bhamidimarri, M. Broenstrup, U. Bilitewski, R.K.R. Marreddy, K.M. Pos, L. Benier, P. Gribbon, M. Winterhalter, B. Windshuegel. Biophysical characterization of E. coli TolC interaction with the known blocker hexaamminecobalt.Biochim Biophys Acta. 2017 Nov;1861(11 Pt A):2702-2709. Epub 2017 Jul 23. doi: 10.1016/j.bbagen.2017.07.014. Ramaswamy, V. K., Vargiu, A.V., Malloci, G., Dreier, J. G., & Ruggerone, P. Molecular rationale behind the differential substrate specificity of bacterial RND multi-drug transporters. Scientific Reports 7, Article number: 8075(2017) doi:10.1038/s41598-017-08747-8. Harsha Bajaj, Silvia Acosta-Gutiérrez, Igor Bodrenko, Giuliano Malloci, Mariano Andrea Scorciapino, Mathias Winterhalter and Matteo Ceccarelli. Bacterial Outer Membrane Porins ...
Molecular dynamics simulations by Department of Biochemistrys Dr Phillip Stansfeld, in the lab of Professor Mark Sansom, have helped to reveal how bacteria construct a barrier against antibiotics and the bodys immune system.
The asymmetric outer membrane of Gram-negative bacteria is formed of the inner leaflet with phospholipids and the outer leaflet with lipopolysaccharides (LPS). Outer membrane protein F (OmpF) is a trimeric porin responsible for the passive transport of small molecules across the outer membrane of Escherichia coli. Here, we report the impact of different levels of heterogeneity in LPS environments on the structure and dynamics of OmpF using all-atom molecular dynamics simulations. The simulations provide insight into the flexibility and dynamics of LPS components that are highly dependent on local environments, with lipid A being the most rigid and O-antigen being the most flexible. Increased flexibility of O-antigen polysaccharides is observed in heterogeneous LPS systems, where the adjacent O-antigen repeating units are weakly interacting and thus more dynamic, compared to homogeneous LPS systems in which LPS interacts strongly with each other with limited overall flexibility due to dense ...
Pseudomonas aeruginosa is an important opportunistic pathogen that can cause chronic and often life-threatening infections of the respiratory tract, particularly in individuals with cystic fibrosis (CF). Because infections with P. aeruginosa remain the major cause of the high morbidity and mortality of CF, a vaccine against P. aeruginosa would be very useful for preventing this disorder. The outer membrane protein F (OprF) of P. aeruginosa is a promising vaccine candidate and various B cell epitopes within OprF have been identified. Given that adenovirus (Ad) vectors have strong immunogenic potential and can function as adjuvants for genetic vaccines, the present study evaluates the immunogenic and protective properties of a novel replication-deficient Ad vector in which the Ad hexon protein was modified to include a 14-amino acid epitope of P. aeruginosa OprF (Epi8) in loop 1 of the hypervariable region 5 of the hexon (AdZ.Epi8). Immunization of C57BL/6 mice with AdZ.Epi8 resulted in detectable ...
Dispensable loops shield the functionally-important extracellular loops of the essential Gram-negative bacterial outer membrane protein LptD from antibody interference.
Anand A, LeDoyt M, Karanian C, Luthra A, Koszelak-Rosenblum M, Malkowski MG, Puthenveetil R, Vinogradova O, Radolf JD. Bipartite Topology of Treponema pallidum Repeat Proteins C/D and I: OUTER MEMBRANE INSERTION, TRIMERIZATION, AND PORIN FUNCTION REQUIRE A C-TERMINAL ß-BARREL DOMAIN. J Biol Chem. 2015 May 08; 290(19):12313-31 ...
In biochemistry, a protein trimer is a macromolecular complex formed by three, usually non-covalently bound, macromolecules like proteins or nucleic acids. A homo-trimer would be formed by three identical molecules. A hetero-trimer would be formed by three different macromolecules. Type II Collagen is an example of homo-trimeric protein. Porins usually arrange themselves in membranes as trimers. ...
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A - Tilt: 3° - Segments: 1( 6- 16), 2( 31- 39), 3( 43- 50), 4( 68- 78), 5( 85- 92), 6( 111- 120), 7( 128- 136), 8( 151- 160), 9( 167- 174), 10( 192- 201), 11( 204- 214), 12( 223- 230), 13( 237- 244), 14( 259- 268 ...
A - Tilt: 5° - Segments: 1( 6- 16), 2( 31- 41), 3( 42- 50), 4( 68- 78), 5( 84- 92), 6( 111- 122), 7( 127- 135), 8( 151- 161), 9( 166- 173), 10( 192- 200), 11( 204- 212), 12( 234- 244), 13( 247- 256), 14( 271- 279 ...
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Phlogenzym je obvykle dobre znášaný, ani pri dlhodobom užívaní vysokých dávok neboli pozorované nežiaduce účinky. Pôsobením enzýmov môžu nastať neškodné zmeny farby, pachu a konzistencie stolice. Počas užívania vyšších jednorázových dávok sa môžu objaviť pocity plnosti, nafukovania a výnimočne pocit nevoľnosti. Tomu sa dá zabrániť rozdelením dávky na viacero dávok v priebehu dňa. Ak tieto príznaky aj po znížení dávky pretrvávajú, poraďte sa s lekárom. Zriedka pozorované alergické reakcie (kožná vyrážka) odoznejú po vysadení lieku. Pri ich prípadnom výskyte prerušte užívanie Phlogenzymu a poraďte sa s lekárom. Zriedkavými nežiaducimi účinkami sú: bolesť hlavy, pocit hladu a zvýšená potivosť. S lekárom sa o ďalšom užívaní Phlogenzymu poraďte aj v prípade výskytu akýchkoľvek neobvyklých reakcií ...
The Dashs sock-like bootie design, which keeps out debris, is combined with arch-lasted construction for a supportive fit. Lacing is asymmetrical with offset eyelets that help to reinforce the support.
Forms a channel through the cell membrane that allows diffusion of small hydrophilic molecules (By similarity). Plays a role in maintaining mitochondrial morphology (PubMed:25190516).
p>The checksum is a form of redundancy check that is calculated from the sequence. It is useful for tracking sequence updates.,/p> ,p>It should be noted that while, in theory, two different sequences could have the same checksum value, the likelihood that this would happen is extremely low.,/p> ,p>However UniProtKB may contain entries with identical sequences in case of multiple genes (paralogs).,/p> ,p>The checksum is computed as the sequence 64-bit Cyclic Redundancy Check value (CRC64) using the generator polynomial: x,sup>64,/sup> + x,sup>4,/sup> + x,sup>3,/sup> + x + 1. The algorithm is described in the ISO 3309 standard. ,/p> ,p class=publication>Press W.H., Flannery B.P., Teukolsky S.A. and Vetterling W.T.,br /> ,strong>Cyclic redundancy and other checksums,/strong>,br /> ,a href=http://www.nrbook.com/b/bookcpdf.php>Numerical recipes in C 2nd ed., pp896-902, Cambridge University Press (1993),/a>),/p> Checksum:i ...
OprF is a major outer membrane protein from Pseudomonas aeruginosa, a homolog of OmpA from Escherichia coli. The N-terminal domains of both proteins have been demonstrated to form low conductance channels in lipid bilayers. Homology models, consisting of an eight-stranded beta-barrel, of the N-terminal domain OprF have been constructed based on the crystal structure of the corresponding domain from E. coli OmpA. OprF homology models have been evaluated via a set (6 x 10 ns) of simulations of the beta-barrel embedded within a solvated dimyristoyl-phosphatidylcholine (DMPC) bilayer. The conformational stability of the models is similar to that of the crystal structure of OmpA in comparable simulations. There is a degree of water penetration into the pore-like center of the OprF barrel. The presence of an acidic/basic (E8/K121) side-chain interaction within the OprF barrel may form a gate able to close/open a central pore. Lipid-protein interactions within the simulations were analyzed and revealed that
The protein encoded by this gene belongs to the BCL2 protein family. BCL2 family members form hetero- or homodimers and act as anti- or pro-apoptotic regulators that are involved in a wide variety of cellular activities. This protein forms a heterodimer with BCL2, and functions as an apoptotic activator. This protein is reported to interact with, and increase the opening of, the mitochondrial voltage-dependent anion channel (VDAC), which leads to the loss in membrane potential and the release of cytochrome c. The expression of this gene is regulated by the tumor suppressor P53 and has been shown to be involved in P53-mediated apoptosis. Multiple alternatively spliced transcript variants, which encode different isoforms, have been reported for this gene. Product Name ...
The protein encoded by this gene belongs to the BCL2 protein family. BCL2 family members form hetero- or homodimers and act as anti- or pro-apoptotic regulators that are involved in a wide variety of cellular activities. This protein forms a heterodimer with BCL2, and functions as an apoptotic activator. This protein is reported to interact with, and increase the opening of, the mitochondrial voltage-dependent anion channel (VDAC), which leads to the loss in membrane potential and the release of cytochrome c. The expression of this gene is regulated by the tumor suppressor P53 and has been shown to be involved in P53-mediated apoptosis. Multiple alternatively spliced transcript variants, which encode different isoforms, have been reported for this gene. Product Name ...
The protein encoded by this gene belongs to the BCL2 protein family. BCL2 family members form oligomers or heterodimers and act as anti- or pro-apoptotic regulators that are involved in a wide variety of cellular activities. This protein localizes to mitochondria, and functions to induce apoptosis. It interacts with and accelerates the opening of the mitochondrial voltage-dependent anion channel, which leads to a loss in membrane potential and the release of cytochrome c. This protein also interacts with the tumor suppressor P53 after exposure to cell stress. [provided by RefSeq, Jul 2008] ...
Sugar permeation through maltoporin of Escherichia coli, a trimer protein that facilitates maltodextrin translocation across outer bacterial membranes, was investigated at the single channel level. For large sugars, such as maltohexaose, elementary e
Khandelwal and colleagues succeeded in identifying the insecticidal factor. The active component was found in a large complex normally associated with the bacterial outer membrane, and was also present in or on outer membrane vesicles (OMVs) released from the bacterial surface, says Khandelwal. They then searched through OMV components and identified a small (17 kDa) toxic protein. When purified, this protein was toxic to cultured larval cells and directly killed H. armigera larvae. Gene cloning and sequencing showed this protein is related to a class of bacterial outer membrane proteins that form protrusions, called pili or fimbriae, which often help bacteria attach to host cells during infection. Similar to pili proteins, the purified 17 kDa protein self-associated to form oligomers, each of which was connected to the next by a strand. Most importantly, the recombinant 17 kDa protein killed H. armigera larvae, demonstrating its potential as a biological control agent in a world desperately in ...
An axial flow staged zone oligomerization reaction process includes the steps of passing a hydrocarbon feedstock into the lower portion of the axial flow staged zone reactor which includes axial circulation of the hydrocarbon reaction fluid serially in each of the reaction zones, passing catalyst through a constriction zone located between successive upper and lower catalytic reaction zones which includes heat exchanging of the fluids being the constriction zone within the reactor and further includes withdrawing the oligomerized product from the top of the reactor.
Introduction. The marA, soxS, ramA, acrB and ompF genes have been studied in order to characterize mechanisms of AcrAB-TolC active efflux pumps and membrane permeability alterations that reduce fluoroquinolones susceptibility in Salmonella spp. Methods. Mutations in marA, soxS, ramA, acrB and ompF genes were detected, as well as their expression levels in presence and absence of ciprofloxacin, calculating the level of change between them by qPCR. Data were analysed by using SPSS 19.0. Results. No mutations in these genes were found, but both AcrAB-TolC regulatory genes and structural acrB gene expression were affected by ciprofloxacin in both mutant strains and wild type bacterial strains (WT ...
Using mathematical models that combine population genetic and epidemiological processes, we resolve the paradox that many important pathogens appear to persist as discrete strains despite the constant exchange of genetic material. We show that dominant polymorphic determinants (that is, those that elicit the most effective immune responses) will be organized into nonoverlapping combinations as a result of selection by the host immune system, thereby defining a set of discrete independently transmitted strains. By analysing 222 isolates of Neisseria meningitidis, we show that two highly polymorphic epitopes of the outer membrane protein PorA exist in nonoverlapping combinations as predicted by this general framework. The model indicates that dominant polymorphic determinants will be in linkage disequilibrium, despite frequent genetic exchange, even though they may be encoded by several unlinked genes. This suggests that the detection of nonrandom associations between epitope regions can be employed as a
TY - JOUR. T1 - The effect of altered porin expression in Escherichia coli upon susceptibility to 4-quinolones. AU - Piddock, L J. AU - Wise, R. PY - 1986/10. Y1 - 1986/10. KW - Bacterial Proteins. KW - Escherichia coli. KW - Gene Expression Regulation. KW - Microbial Sensitivity Tests. KW - Quinolines. M3 - Article. C2 - 3533892. VL - 18. SP - 547. EP - 549. JO - Journal of Antimicrobial Chemotherapy. JF - Journal of Antimicrobial Chemotherapy. SN - 0305-7453. IS - 4. ER - ...
Simple and facilitated diffusion: Diffusion of molecules or ions through a membrane is of two types - simple and facilitated. The simple diffusion refers to the type of transfer in which the diffusing molecules or ions do not combine with the constituents of the membrane. For example, gases like oxygen, carbon dioxide etc., and water molecules diffuse readily through gas created by the random movement of fatty acyl chain of lipids. The facilitated diffusion is the movement through the membrane with the help of certain transport proteins. Membranes have several such proteins which facilitate the diffusion of solutes (Cl-, HCO3- etc.) Plasma membranes of some organisms have protein pores called, porins which are water-filled transmembrane channels.. ...
Import of porin is inhibited into tom40 mutant mitochondria. (A) Radiolabeled porin precursor (10 μl reticulocyte lysate per lane) was incubated with isolated
The expression of the clpP gene, and probably the expression of the complete clpPX operon that codes for a protease, is affected by antibiotic pressure. As the antibiotic (tetracycline) concentration increases, the gene expression also increases. The role of the induced protease could be the degradation of porins to protect the cell against the antibiotic ,CITS: [17426813],. ...
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