330 research outputs found
Observation of resonances consistent with pentaquark states in decays
Observations of exotic structures in the channel, that we refer to
as pentaquark-charmonium states, in decays are
presented. The data sample corresponds to an integrated luminosity of 3/fb
acquired with the LHCb detector from 7 and 8 TeV pp collisions. An amplitude
analysis is performed on the three-body final-state that reproduces the
two-body mass and angular distributions. To obtain a satisfactory fit of the
structures seen in the mass spectrum, it is necessary to include two
Breit-Wigner amplitudes that each describe a resonant state. The significance
of each of these resonances is more than 9 standard deviations. One has a mass
of MeV and a width of MeV, while the second
is narrower, with a mass of MeV and a width of MeV. The preferred assignments are of opposite parity, with one
state having spin 3/2 and the other 5/2.Comment: 48 pages, 18 figures including the supplementary material, v2 after
referee's comments, now 19 figure
Measurement of the CKM angle Îł from a combination of B±âDh± analyses
A combination of three LHCb measurements of the CKM angle Îł is presented. The decays B±âD K± and
B±âDϱ are used, where D denotes an admixture of D0 and D0 mesons, decaying into K+Kâ, Ï+Ïâ, K±Ïâ, K±ÏâϱÏâ, K0SÏ+Ïâ, or K0S K+Kâ ïŹnal states. All measurements use a dataset corresponding to 1.0 fbâ1 of integrated luminosity. Combining results from B±âD K± decays alone a best-ïŹt value of
Îł =72.0⊠is found, and conïŹdence intervals are set
Îł â [56.4,86.7]⊠at 68% CL,
Îł â [42.6,99.6]⊠at 95% CL.
The best-ïŹt value of Îł found from a combination of results from B±âDϱ decays alone, is Îł =18.9âŠ,
and the conïŹdence intervals
Îł â [7.4,99.2]⊠âȘ [167.9,176.4]⊠at 68% CL
are set, without constraint at 95% CL. The combination of results from B± â D K± and B± â Dϱ
decays gives a best-ïŹt value of Îł =72.6⊠and the conïŹdence intervals
Îł â [55.4,82.3]⊠at 68% CL,
Îł â [40.2,92.7]⊠at 95% CL
are set. All values are expressed modulo 180âŠ, and are obtained taking into account the effect of D0âD0
mixing
Study of decays to the final state and evidence for the decay
A study of decays is performed for the first time
using data corresponding to an integrated luminosity of 3.0
collected by the LHCb experiment in collisions at centre-of-mass energies
of and TeV. Evidence for the decay
is reported with a significance of 4.0 standard deviations, resulting in the
measurement of
to
be .
Here denotes a branching fraction while and
are the production cross-sections for and mesons.
An indication of weak annihilation is found for the region
, with a significance of
2.4 standard deviations.Comment: All figures and tables, along with any supplementary material and
additional information, are available at
https://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-PAPER-2016-022.html,
link to supplemental material inserted in the reference
Amplitude analysis of decays
The first full amplitude analysis of with
, decays is performed with a data sample
of 3 fb of collision data collected at and TeV
with the LHCb detector. The data cannot be described by a model that contains
only excited kaon states decaying into , and four
structures are observed, each with significance over standard deviations.
The quantum numbers of these structures are determined with significance of at
least standard deviations. The lightest has mass consistent with, but width
much larger than, previous measurements of the claimed state. The
model includes significant contributions from a number of expected kaon
excitations, including the first observation of the
transition.Comment: 62 pages 26 figure
C-Terminus Glycans with Critical Functional Role in the Maturation of Secretory Glycoproteins
The N-glycans of membrane glycoproteins are mainly exposed to the extracellular space. Human tyrosinase is a transmembrane glycoprotein with six or seven bulky N-glycans exposed towards the lumen of subcellular organelles. The central active site region of human tyrosinase is modeled here within less than 2.5 Ă
accuracy starting from Streptomyces castaneoglobisporus tyrosinase. The model accounts for the last five C-terminus glycosylation sites of which four are occupied and indicates that these cluster in two pairs - one in close vicinity to the active site and the other on the opposite side. We have analyzed and compared the roles of all tyrosinase N-glycans during tyrosinase processing with a special focus on the proximal to the active site N-glycans, s6:N337 and s7:N371, versus s3:N161 and s4:N230 which decorate the opposite side of the domain. To this end, we have constructed mutants of human tyrosinase in which its seven N-glycosylation sites were deleted. Ablation of the s6:N337 and s7:N371 sites arrests the post-translational productive folding process resulting in terminally misfolded mutants subjected to degradation through the mannosidase driven ERAD pathway. In contrast, single mutants of the other five N-glycans located either opposite to the active site or into the N-terminus Cys1 extension of tyrosinase are temperature-sensitive mutants and recover enzymatic activity at the permissive temperature of 31°C. Sites s3 and s4 display selective calreticulin binding properties. The C-terminus sites s7 and s6 are critical for the endoplasmic reticulum retention and intracellular disposal. Results herein suggest that individual N-glycan location is critical for the stability, regional folding control and secretion of human tyrosinase and explains some tyrosinase gene missense mutations associated with oculocutaneous albinism type I
Accurate Prediction of Protein Structural Class
Because of the increasing gap between the data from sequencing and structural genomics, the accurate prediction of the structural class of a protein domain solely from the primary sequence has remained a challenging problem in structural biology. Traditional sequence-based predictors generally select several sequence features and then feed them directly into a classification program to identify the structural class. The current best sequence-based predictor achieved an overall accuracy of 74.1% when tested on a widely used, non-homologous benchmark dataset 25PDB. In the present work, we built a multiple linear regression (MLR) model to convert the 440-dimensional (440D) sequence feature vector extracted from the Position Specific Scoring Matrix (PSSM) of a protein domain to a 4-dimensinal (4D) structural feature vector, which could then be used to predict the four major structural classes. We performed 10-fold cross-validation and jackknife tests of the method on a large non-homologous dataset containing 8,244 domains distributed among the four major classes. The performance of our approach outperformed all of the existing sequence-based methods and had an overall accuracy of 83.1%, which is even higher than the results of those predicted secondary structure-based methods
Molecular Cloning, Characterization and Expression Analysis of Two Members of the Pht1 Family of Phosphate Transporters in Glycine max
BACKGROUND: Phosphorus is one of the macronutrients essential for plant growth and development. The acquisition and translocation of phosphate are pivotal processes of plant growth. In a large number of plants, phosphate uptake by roots and translocation within the plant are presumed to occur via a phosphate/proton cotransport mechanism. PRINCIPAL FINDINGS: We cloned two cDNAs from soybean (Glycine max), GmPT1 and GmPT2, which show homology to the phosphate/proton cotransporter PHO84 from the budding yeast Saccharomyces cerevisiae. The amino acid sequence of the products predicted from GmPT1 and GmPT2 share 61% and 63% identity, respectively, with the PHO84 in amino acid sequence. The deduced structure of the encoded proteins revealed 12 membrane-spanning domains with a central hydrophilic region. The molecular mass values are âŒ58.7 kDa for GmPT1 and âŒ58.6 kDa for GmPT2. Transiently expressed GFP-protein fusions provide direct evidence that the two Pi transporters are located in the plasma membrane. Uptake of radioactive orthophosphate by the yeast mutant MB192 showed that GmPT1 and GmPT2 are dependent on pH and uptake is reduced by the addition of uncouplers of oxidative phosphorylation. The K(m) for phosphate uptake by GmPT1 and GmPT2 is 6.65 mM and 6.63 mM, respectively. A quantitative real time RT-PCR assay indicated that these two genes are expressed in the roots and shoots of seedlings whether they are phosphate-deficient or not. Deficiency of phosphorus caused a slight change of the expression levels of GmPT1 and GmPT2. CONCLUSIONS: The results of our experiments show that the two phosphate transporters have low affinity and the corresponding genes are constitutively expressed. Thereby, the two phosphate transporters can perform translocation of phosphate within the plant
Differential branching fractions and isospin asymmetries of B -> K ((*)) Ό(+) Ό(-) decays
The isospin asymmetries of B -> K Ό(+) Ό(-) and B -> K (*) Ό(+) Ό(-) decays and the partial branching fractions of the B (0) -> K (0) Ό(+) Ό(-), B (+) -> K (+) Ό(+) Ό(-) and B (+) -> K (*+) Ό(+) Ό(-) decays are measured as functions of the dimuon mass squared, q (2). The data used correspond to an integrated luminosity of 3 fb(-1) from proton-proton collisions collected with the LHCb detector at centre-of-mass energies of 7 TeV and 8 TeV in 2011 and 2012, respectively. The isospin asymmetries are both consistent with the Standard Model expectations. The three measured branching fractions favour lower values than their respective theoretical predictions, however they are all individually consistent with the Standard Model
Measurement of the CP-violating phase Ïs in BÂŻs0âDs+Dsâ decays
We present a measurement of the CP-violating weak mixing phase Ïs using the decay BÂŻ0sâD+sDâs in a data sample corresponding to 3.0âfbâ1 of integrated luminosity collected with the LHCb detector in pp collisions at center-of-mass energies of 7 and 8 TeV. An analysis of the time evolution of the system, which does not use the constraint |λ|=1 to allow for the presence of CP violation in decay, yields Ïs=0.02±0.17(stat)±0.02(syst)âârad, |λ|=0.91+0.18â0.15(stat)±0.02(syst). This result is consistent with the standard model expectation
Observation of the B0 â Ï0Ï0 decay from an amplitude analysis of B0 â (Ï+Ï-)(Ï+Ï-) decays
Proton-proton collision data recorded in 2011 and 2012 by the LHCb experiment, corresponding to an integrated luminosity of 3.0 fb-1, are analysed to search for the charmless B0âÏ0Ï0 decay. More than 600 B0â(Ï+Ï-)(Ï+Ï-) signal decays are selected and used to perform an amplitude analysis, under the assumption of no CP violation in the decay, from which the B0âÏ0Ï0 decay is observed for the first time with 7.1 standard deviations significance. The fraction of B0âÏ0Ï0 decays yielding a longitudinally polarised final state is measured to be fL=0.745-0.058+0.048(stat)±0.034(syst). The B0âÏ0Ï0 branching fraction, using the B0âÏK*(892)0 decay as reference, is also reported as B(B0âÏ0Ï0)=(0.94±0.17(stat)±0.09(syst)±0.06(BF))Ă10-6
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