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41.
42.
Doble E. A.; Leiter J. C.; Knuth S. L.; Daubenspeck J. A.; Bartlett D. Jr 《Journal of applied physiology》1985,58(4):1378-1382
We have developed an intraoral bipolar surface electrode for the genioglossus muscle. The electrode, made from an athletic mouthguard and dental impression material, was fitted to the lower teeth. Electrode wires, bared at the tip, were positioned on the bottom of the mouthpiece to lie in contact with the superior surface of the genioglossus just behind the teeth. The electromyographic activity of the genioglossus, simultaneously obtained from the surface electrode and conventional intramuscular electrodes, was compared during quiet breathing, CO2 rebreathing, and a variety of tongue movements. The two types of electrodes recorded similar patterns of muscle activity, and spectral analyses of the signals revealed similar and highly coherent frequency spectra. We conclude that the surface electrode satisfactorily reflects the bioelectrical activity of the genioglossus. The mouthpiece electrode has the further advantage that quantitative comparisons can be made among recordings made in different experimental sessions, since the fit of the mouthpiece to the teeth assures a constant relationship of the electrode to the genioglossus muscle. 相似文献
43.
Xu Q Rawlings ND Chiu HJ Jaroszewski L Klock HE Knuth MW Miller MD Elsliger MA Deacon AM Godzik A Lesley SA Wilson IA 《PloS one》2011,6(7):e22013
NlpC/P60 superfamily papain-like enzymes play important roles in all kingdoms of life. Two members of this superfamily, LRAT-like and YaeF/YiiX-like families, were predicted to contain a catalytic domain that is circularly permuted such that the catalytic cysteine is located near the C-terminus, instead of at the N-terminus. These permuted enzymes are widespread in virus, pathogenic bacteria, and eukaryotes. We determined the crystal structure of a member of the YaeF/YiiX-like family from Bacillus cereus in complex with lysine. The structure, which adopts a ligand-induced, "closed" conformation, confirms the circular permutation of catalytic residues. A comparative analysis of other related protein structures within the NlpC/P60 superfamily is presented. Permutated NlpC/P60 enzymes contain a similar conserved core and arrangement of catalytic residues, including a Cys/His-containing triad and an additional conserved tyrosine. More surprisingly, permuted enzymes have a hydrophobic S1 binding pocket that is distinct from previously characterized enzymes in the family, indicative of novel substrate specificity. Further analysis of a structural homolog, YiiX (PDB 2if6) identified a fatty acid in the conserved hydrophobic pocket, thus providing additional insights into possible function of these novel enzymes. 相似文献
44.
Xu Q Saikatendu KS Krishna SS McMullan D Abdubek P Agarwalla S Ambing E Astakhova T Axelrod HL Carlton D Chiu HJ Clayton T DiDonato M Duan L Elsliger MA Feuerhelm J Grzechnik SK Hale J Hampton E Han GW Haugen J Jaroszewski L Jin KK Klock HE Knuth MW Koesema E Miller MD Morse AT Nigoghossian E Okach L Oommachen S Paulsen J Reyes R Rife CL Schwarzenbacher R van den Bedem H White A Wolf G Hodgson KO Wooley J Deacon AM Godzik A Lesley SA Wilson IA 《Proteins》2007,69(2):433-439
45.
Zubieta C Joseph R Krishna SS McMullan D Kapoor M Axelrod HL Miller MD Abdubek P Acosta C Astakhova T Carlton D Chiu HJ Clayton T Deller MC Duan L Elias Y Elsliger MA Feuerhelm J Grzechnik SK Hale J Han GW Jaroszewski L Jin KK Klock HE Knuth MW Kozbial P Kumar A Marciano D Morse AT Murphy KD Nigoghossian E Okach L Oommachen S Reyes R Rife CL Schimmel P Trout CV van den Bedem H Weekes D White A Xu Q Hodgson KO Wooley J Deacon AM Godzik A Lesley SA Wilson IA 《Proteins》2007,69(2):234-243
TyrA is a member of the dye-decolorizing peroxidase (DyP) family, a new family of heme-dependent peroxidase recently identified in fungi and bacteria. Here, we report the crystal structure of TyrA in complex with iron protoporphyrin (IX) at 2.3 A. TyrA is a dimer, with each monomer exhibiting a two-domain, alpha/beta ferredoxin-like fold. Both domains contribute to the heme-binding site. Co-crystallization in the presence of an excess of iron protoporphyrin (IX) chloride allowed for the unambiguous location of the active site and the specific residues involved in heme binding. The structure reveals a Fe-His-Asp triad essential for heme positioning, as well as a novel conformation of one of the heme propionate moieties compared to plant peroxidases. Structural comparison to the canonical DyP family member, DyP from Thanatephorus cucumeris (Dec 1), demonstrates conservation of this novel heme conformation, as well as residues important for heme binding. Structural comparisons with representative members from all classes of the plant, bacterial, and fungal peroxidase superfamily demonstrate that TyrA, and by extension the DyP family, adopts a fold different from all other structurally characterized heme peroxidases. We propose that a new superfamily be added to the peroxidase classification scheme to encompass the DyP family of heme peroxidases. 相似文献
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47.
Novel Bacillus thuringiensis Binary Insecticidal Crystal Proteins Active on Western Corn Rootworm, Diabrotica virgifera virgifera LeConte 下载免费PDF全文
R. Tracy Ellis Brian A. Stockhoff Lisa Stamp H. Ernest Schnepf George E. Schwab Mark Knuth Josh Russell Guy A. Cardineau Kenneth E. Narva 《Applied microbiology》2002,68(3):1137-1145
A new family of insecticidal crystal proteins was discovered by screening sporulated Bacillus thuringiensis cultures for oral activity against western corn rootworm (WCR) larvae. B. thuringiensis isolates PS80JJ1, PS149B1, and PS167H2 have WCR insecticidal activity attributable to parasporal inclusion bodies containing proteins with molecular masses of ca. 14 and 44 kDa. The genes encoding these polypeptides reside in apparent operons, and the 14-kDa protein open reading frame (ORF) precedes the 44-kDa protein ORF. Mutagenesis of either gene in the apparent operons dramatically reduced insecticidal activity of the corresponding recombinant B. thuringiensis strain. Bioassays performed with separately expressed, biochemically purified 14- and 44-kDa polypeptides also demonstrated that both proteins are required for WCR mortality. Sequence comparisons with other known B. thuringiensis insecticidal proteins failed to reveal homology with previously described Cry, Cyt, or Vip proteins. However, there is evidence that the 44-kDa polypeptide and the 41.9- and 51.4-kDa binary dipteran insecticidal proteins from Bacillus sphaericus are evolutionarily related. The 14- and 44-kDa polypeptides from isolates PS80JJ1, PS149B1, and PS167H2 have been designated Cry34Aa1, Cry34Ab1, and Cry34Ac1, respectively, and the 44-kDa polypeptides from these isolates have been designated Cry35Aa1, Cry35Ab1, and Cry35Ac1, respectively. 相似文献
48.
49.
Qingping Xu Tadashi Eguchi Christopher L. Rife Hsiu-Ju Chiu Carol L. Farr Julie Feuerhelm Lukasz Jaroszewski Heath E. Klock Mark W. Knuth Mitchell D. Miller Dana Weekes Marc-André Elsliger Ashley M. Deacon Adam Godzik Scott A. Lesley Ian A. Wilson 《Journal of molecular biology》2010,404(3):403-417
Archaeal membrane lipids consist of branched, saturated hydrocarbons distinct from those found in bacteria and eukaryotes. Digeranylgeranylglycerophospholipid reductase (DGGR) catalyzes the hydrogenation process that converts unsaturated 2,3-di-O-geranylgeranylglyceryl phosphate to saturated 2,3-di-O-phytanylglyceryl phosphate as a critical step in the biosynthesis of archaeal membrane lipids. The saturation of hydrocarbon chains confers the ability to resist hydrolysis and oxidation and helps archaea withstand extreme conditions. DGGR is a member of the geranylgeranyl reductase family that is also widely distributed in bacteria and plants, where the family members are involved in the biosynthesis of photosynthetic pigments. We have determined the crystal structure of DGGR from the thermophilic heterotrophic archaea Thermoplasma acidophilum at 1.6 Å resolution, in complex with flavin adenine dinucleotide (FAD) and a bacterial lipid. The DGGR structure can be assigned to the well-studied, p-hydroxybenzoate hydroxylase (PHBH) SCOP superfamily of flavoproteins that include many aromatic hydroxylases and other enzymes with diverse functions. In the DGGR complex, FAD adopts the IN conformation (closed) previously observed in other PHBH flavoproteins. DGGR contains a large substrate-binding site that extends across the entire ligand-binding domain. Electron density corresponding to a bacterial lipid was found within this cavity. The cavity consists of a large opening that tapers down to two, narrow, curved tunnels that closely mimic the shape of the preferred substrate. We identified a sequence motif, PxxYxWxFP, that defines a specificity pocket in the enzyme and precisely aligns the double bond of the geranyl group with respect to the FAD cofactor, thus providing a structural basis for the substrate specificity of geranylgeranyl reductases. DGGR is likely to share a common mechanism with other PHBH enzymes in which FAD switches between two conformations that correspond to the reductive and oxidative half cycles. The structure provides evidence that substrate binding likely involves conformational changes, which are coupled to the two conformational states of the FAD. 相似文献
50.
Hai-Zhi Bu Lisa Magis Kim Knuth Philip Teitelbaum 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》2001,753(2)
A highly efficient direct injection/on-line guard cartridge extraction–tandem mass spectrometry (DI/GCE–MS–MS) method has been validated for high-throughput evaluation of cytochrome P450 (CYP) 2D6 inhibition potential using human hepatic microsomes and 96-well microtiter plates. Microsomal incubations were terminated with formic acid, centrifuged, and the resulting supernatants were injected for DI/GCE–MS–MS analysis. Due to the novel use of an extremely short C18 guard cartridge, this method exhibits several advantages, such as no sample preparation, excellent on-line extraction, short run time (2.5 min), and minimized source contamination and performance deterioration. The DI/GCE–MS–MS method demonstrates acceptable accuracy and precision for the quantification of dextrorphan, a marker metabolite of dextromethorphan mediated by CYP2D6, in microsomal incubations. The CYP2D6 inhibition assay has been validated using quinidine as a known selective inhibitor of the isoform. The IC50 value (0.20 μM) measured by the new method is in good agreement with the literature value (0.22 μM). 相似文献