共查询到20条相似文献,搜索用时 15 毫秒
1.
Permi P 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2003,163(1):114-120
Triple-resonance NMR experiments for measuring three-bond scalar coupling constant between 13C' (i-1) and 1H(alpha)(i) spins, defining the dihedral angle phi, are presented. The novel experiments enable the measurement of 3JC'H(alpha)) from simple two (or three)-dimensional 13C', (15N/13C(alpha)), 1H(N) correlation spectra with minimal resonance overlap, thanks to solely intraresidual coherence transfer pathway and spin-state-selection. The 3J(C'H(alpha)) values measured in human ubiquitin using the proposed intraresidual iHN(CA),CO(alpha/beta-J-COHA) TROSY method were compared with those determined previously utilizing the HCAN[C'] experiment. 相似文献
2.
Werner-Allen JW Jiang L Zhou P 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2006,181(1):177-180
Among the suite of commonly used backbone experiments, HNCACO presents an unresolved sensitivity limitation due to fast 13CO transverse relaxation and passive 13Calpha-13Cbeta coupling. Here, we present a high-sensitivity 'just-in-time' (JIT) HN(CA)CO pulse sequence that uniformly refocuses 13Calpha-13Cbeta coupling while collecting 13CO shifts in real time. Sensitivity comparisons of the 3-D JIT HN(CA)CO, a CT-HMQC-based control, and a HSQC-based control with selective 13Calpha inversion pulses were performed using a 2H/13C/15N labeled sample of the 29 kDa HCA II protein at 15 degrees C. The JIT experiment shows a 42% signal enhancement over the CT-HMQC-based experiment. Compared to the HSQC-based experiment, the JIT experiment is 16% less sensitive for residues experiencing proper 13Calpha refocusing and13Calpha-13Cbeta decoupling. However, for the remaining residues, the JIT spectrum shows a 106% average sensitivity gain over the HSQC-based experiment. The high-sensitivity JIT HNCACO experiment should be particularly beneficial for studies of large proteins to provide 13CO resonance information regardless of residue type. 相似文献
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We demonstrate that the backbone torsion psi angle of a uniformly labeled residue can be determined accurately by correlating the chemical shift anisotropy of the carbonyl carbon and the 13C-1H heteronuclear dipole-dipole interaction of the alpha carbon. To obtain the highest sensitivity for the psi angle determination, the following conditions are desired: (i) the recoupling pulse sequences for the CSA and the heteronuclear dipolar interactions are gamma encoded, in which the spatial parts of m=2 are selected; (ii) the homonuclear polarization transfer is based on the scalar spin-spin coupling. Experimental data were obtained for [U-13C, 15N]-alanine and N-acetyl-[U-13C, 15N]-d,l-valine under magic-angle spinning at 25kHz. Only three data points are required for the measurements and the dihedral angles determined are in excellent agreement with the diffraction data. 相似文献
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Ladizhansky V Veshtort M Griffin RG 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2002,154(2):317-324
Several existing methods permit measurement of the torsion angles phi, psi and chi in peptides and proteins with solid-state MAS NMR experiments. Currently, however, there is not an approach that is applicable to measurement of psi in the angular range -20 degree to -70 degree, commonly found in alpha-helical structures. Accordingly, we have developed a HCCN dipolar correlation MAS experiment that is sensitive and accurate in this regime. An initial REDOR driven (13)C'--(15)N dipolar evolution period is followed by the C' to C(alpha) polarization transfer and by Lee--Goldburg cross polarization recoupling of the (13)C(alpha)(1)H dipolar interaction. The difference between the effective (13)C(1)H and (13)C(15)N dipolar interaction strengths is balanced out by incrementing the (13)C--(15)N dipolar evolution period in steps that are a factor of R(R approximately omega(CH)/omega(CN)) larger than the (13)C--(1)H steps. The resulting dephasing curves are sensitive to variations in psi in the angular region associated with alpha-helical secondary structure. To demonstrate the validity of the technique, we apply it to N-formyl-[U-(13)C,(15)N] Met-Leu-Phe-OH (MLF). The value of psi extracted is consistent with the previous NMR measurements and close to that reported in diffraction studies for the methyl ester of MLF, N-formyl-[U-(13)C,(15)N]Met-Leu-Phe-OMe. 相似文献
5.
Miller DH Sanghi B Shipsey IP Xin B Adams GS Anderson M Cummings JP Danko I Ge JY Hu D Moziak B Napolitano J He Q Insler J Muramatsu H Park CS Thorndike EH Yang F Artuso M Blusk S Khalil S Li J Menaa N Mountain R Nisar S Randrianarivony K Sia R Skwarnicki T Stone S Wang JC Bonvicini G Cinabro D Dubrovin M Lincoln A Asner DM Edwards KW Naik P Briere RA Ferguson T Tatishvili G Vogel H Watkins ME Rosner JL Adam NE Alexander JP Cassel DG Duboscq JE Ehrlich R Fields L Gibbons L Gray R Gray SW 《Physical review letters》2007,99(12):122002
We measure the mass of the eta meson using psi(2S) --> etaJ/psi events acquired with the CLEO-c detector operating at the CESR e(+)e(-) collider. Using the four decay modes eta --> gamma gamma, 3pi(0), pi(+)pi(-)pi(0), and pi(+)pi(-)gamma, we find M(eta) = 547.785 +/- 0.017 +/- 0.057 MeV, in which the first uncertainty is statistical and the second systematic. This result has an uncertainty comparable to the two most precise previous measurements and is consistent with that of NA48, but is inconsistent at the level of 6.5 sigma with the much smaller mass obtained by GEM. 相似文献
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Ablikim M Bai JZ Ban Y Cai X Chen HF Chen HS Chen HX Chen JC Chen J Chen YB Chu YP Dai YS Diao LY Deng ZY Dong QF Du SX Fang J Fang SS Fu CD Gao CS Gao YN Gu SD Gu YT Guo YN Guo ZJ Harris FA He KL He M Heng YK Hou J Hu HM Hu JH Hu T Huang XT Ji XB Jiang XS Jiang XY Jiao JB Jin DP Jin S Jin Y Lai YF Li G Li HB Li J Li RY Li SM Li WD Li WG Li XL Li XN Li XQ Liang YF Liao HB Liu BJ Liu CX Liu F Liu F Liu HH Liu HM Liu J Liu JB Liu JP Liu J Liu Q Liu RG Liu ZA Lou YC Lu F Lu GR Lu JG Luo CL Ma FC 《Physical review letters》2008,100(19):192001
Using psi(2S) --> pi(+)pi(-) J/psi events in a sample of 14.0 x 10(6) psi(2S) decays collected with the BES-II detector, a search for the decay of the J/psi to invisible final states is performed. No signal is found, and an upper limit at the 90% confidence level is determined to be 1.2 x 10(-2) for the ratio B(J/psi --> invisible)/B(J/psi-->mu(+)mu(-)). This is the first search for J/psi decays to invisible final states. 相似文献
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Adam NE Alexander JP Berkelman K Cassel DG Crede V Duboscq JE Ecklund KM Ehrlich R Fields L Galik RS Gibbons L Gittelman B Gray R Gray SW Hartill DL Heltsley BK Hertz D Hsu L Jones CD Kandaswamy J Kreinick DL Kuznetsov VE Mahlke-Krüger H Meyer TO Onyisi PU Patterson JR Peterson D Phillips EA Pivarski J Riley D Ryd A Sadoff AJ Schwarthoff H Shepherd MR Stroiney S Sun WM Urner D Wilksen T Weinberger M Athar SB Avery P Breva-Newell L Patel R Potlia V Stoeck H Yelton J Rubin P Cawlfield C 《Physical review letters》2005,94(23):232002
We describe new measurements of the inclusive and exclusive branching fractions for psi(2S) transitions to J/psi using e(+)e(-) collision data collected with the CLEO detector operating at CESR. All branching fractions and ratios of branching fractions reported here represent either the most precise measurements to date or the first direct measurements. Indirectly and in combination with other CLEO measurements, we determine B(chi(cJ) --> gamma(J/psi)) and B[psi(2S) --> light hadrons]. 相似文献
8.
O Millet E Chiarparin P Pelupessy M Pons G Bodenhausen 《Journal of magnetic resonance (San Diego, Calif. : 1997)》1999,139(2):434-438
Several methods are presented for the selective determination of spin-lattice and spin-spin relaxation rates of backbone protons in labeled proteins. The relaxation rates of amide protons in (15)N labeled proteins can be measured by using two-way selective cross-polarization (SCP). The measurement of H(alpha) relaxation rates can be achieved by combining this method with homonuclear Hartmann-Hahn transfer using doubly selective irradiation. Various schemes for selective or nonselective inversion of the longitudinal proton magnetization lead to different initial recovery rates. The methods have been applied to lysine K6 in (15)N-labeled human ubiquitin and to leucine L5 in (15)N- and (13)C-labeled octapeptide YG*G*F*LRRI (GFL) in which the marked residues are (15)N- and (13)C-labeled. 相似文献
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Adam NE Alexander JP Berkelman K Cassel DG Crede V Duboscq JE Ecklund KM Ehrlich R Fields L Galik RS Gibbons L Gittelman B Gray R Gray SW Hartill DL Heltsley BK Hertz D Jones CD Kandaswamy J Kreinick DL Kuznetsov VE Mahlke-Krüger H Meyer TO Onyisi PU Patterson JR Peterson D Phillips EA Pivarski J Riley D Ryd A Sadoff AJ Schwarthoff H Shi X Shepherd MR Stroiney S Sun WM Urner D Wilksen T Weaver KM Weinberger M Athar SB Avery P Breva-Newell L Patel R Potlia V Stoeck H Yelton J Rubin P Cawlfield C 《Physical review letters》2006,96(8):082004
We observe signals for the decays psi(3770) --> XJ/psi from data acquired with the CLEO detector operating at the CESR e+ e- collider with square root of s = 3773 MeV. We measure the following branching fractions Beta(psi(3770) --> XJ/psi and significances: (189 +/- 20 +/- 20) x 10(-5) (11.6sigma) for X = pi+ pi-, (80 +/- 25 +/- 16) x 10(-5) (3.4sigma) for X = pi0 pi0, and (87 +/- 33 +/- 22) x 10(-5) (3.5sigma) for X = eta, where the errors are statistical and systematic, respectively. The radiative return process e+ e- --> gamma psi(2S) populates the same event sample and is used to measure Gamma ee[psi(2S)] = (2.54 +/- 0.03 +/- 0.11) keV. 相似文献
10.
M. Bleuel J.M. Carpenter B.J. Micklich P. Geltenbort K. Mishima H.M. Shimizu Y. Iwashita K. Hirota M. Hino S.J. Kennedy J. Lal 《Physica B: Condensed Matter》2009,404(17):2629-2632
This paper describes the results of SANS measurements of small samples using the very cold neutron (VCN) beam of the PF2 instrument at the Institut Laue Langevin (ILL), France. In addition to a classical SANS pinhole collimation, the experiment used a polarizing supermirror as a monochromator and a magnetic sextupole lens to focus the neutron beam in order to gain intensity and avoid any material in the neutron beam besides the sample. 相似文献
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Leitch MJ Lee WM Beddo ME Brown CN Carey TA Chang TH Cooper WE Gagliardi CA Garvey GT Geesaman DF Hawker EA He XC Isenhower LD Kaplan DM Kaufman SB Koetke DD McGaughey PL Moss JM Mueller BA Papavassiliou V Peng JC Petitt G Reimer PE Sadler ME Sondheim WE Stankus PW 《Physical review letters》2000,84(15):3256-3260
Measurements of the suppression of the yield per nucleon of J/psi and psi(') production for 800 GeV/ c protons incident on heavy nuclear targets, relative to light nuclear targets, have been made with very broad coverage in x(F) and p(T). The observed suppression is smallest at x(F) values of 0.25 and below, and increases at larger values of x(F). It is also strongest at small p(T). Substantial differences between psi(') and J/psi production are observed for the first time in p-A collisions. The suppression for psi(') production is stronger than that for J/psi for x(F) near zero, but becomes comparable to that for J/psi for x(F)>0.6. 相似文献
13.
Gribushin A Abramov V Antipov Y Baldin B Crittenden R Davis C Dauwe L Denisov S Dyshkant A Dzierba A Glebov V Goldberg H Jesik R Koreshev V Krider J Krinitsyn A Li R Margulies S Marshall T Martin J Mendez H Petrukhin A Solomon J Sirotenko V Smith P Sulanke T Sulyaev R Vaca F Zieminski A Blusk S Bromberg C Chang P Choudhary B Chung WH de Barbaro L Dlugosz W Dunlea J Engels E Fanourakis G Ginther G Hartman K Huston J Kapoor V Lirakis C Mani S Mansour J Maul A Miller R Oh BY Pothier E Roser R 《Physical review D: Particles and fields》1996,53(9):4723-4733
14.
The transverse mass spectra of Omega, J/psi, and psi' in Pb+Pb collisions at 158A GeV are studied within a hydrodynamical model of the quark-gluon-plasma expansion and hadronization. The model reproduces the existing data with the common hadronization parameters: temperature T = T(H) congruent with 170 MeV and average collective transverse velocity v(T) congruent with 0.2. 相似文献
15.
Bai JZ Bian JG Chen GP Chen HF Chen SJ Chen SM Chen Y Chen YQ Chen YB Cheng BS Cui XZ Ding HL Ding WY Du ZZ Fan XL Fang J Gao CS Gao ML Gao SQ Gu JH Gu SD Gu WX Gu YF Guo YN Han SW Han Y He J He M Hu GY Hu T Hu XQ Huang DQ Huang T Huang YZ Jiang CH Jin S Jin Y Kang SH Ke ZJ Lai YF Lan HB Lang PF Li F Li J Li PQ Li Q Li RB Li W Li WD Li WG Li XH Li XN Lin SZ Liu HM Liu J Liu JH Liu Q Liu RG Liu Y Liu ZA Lu JG Luo SQ Luo Y Ma AM 《Physical review letters》1996,76(19):3502-3505
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Side-chain carbon resonance assignments are difficult to obtain for larger proteins. While standard methods require protons for excitation and detection of magnetization, their presence is often unacceptable and often leads to unacceptable relaxation losses at the directly bound carbon sites. In this paper, pulse sequences are presented which provide connectivities between aliphatic side-chain (13)C and amide (1)H and (15)N chemical shifts in fully deuterated, (13)C/(15)N-enriched proteins. Magnetization either starts off from carbons or from both nitrogens and protons and is passed along the side-chain via (13)C-(13)C isotropic mixing. Direct rather than (13)CO-relayed (15)N-->(13)C(alpha) or (13)C(alpha)-->(15)N transfer steps allow the detection of intraresidual as well as sequential correlations. To avoid ambiguities between these two types in the three-dimensional version of the experiments, a fourth dimension can be introduced to achieve their separation along a (13)C(alpha) frequency axis. The novel methods are demonstrated with the uniformly (2)H/(13)C/(15)N labeled 35-kDa protein diisopropylfluorophosphatase from Loligo vulgaris. 相似文献
19.
Choi SK Olsen SL Abe K Abe K Adachi I Aihara H Asano Y Bahinipati S Bakich AM Ban Y Bedny I Bitenc U Bizjak I Bondar A Bozek A Bracko M Brodzicka J Browder TE Chang MC Chang P Chen A Chen WT Cheon BG Chistov R Choi Y Chuvikov A Cole S Dalseno J Danilov M Dash M Drutskoy A Eidelman S Enari Y Fang F Fratina S Gabyshev N Gershon T Gokhroo G Golob B Hara T Hastings NC Hayasaka K Hayashii H Hazumi M Hinz L Hokuue T Hoshi Y Hou S Hou WS Hsiung YB Iijima T Imoto A Inami K Ishikawa A Iwasaki M 《Physical review letters》2005,94(18):182002
We report the observation of a near-threshold enhancement in the omegaJ/psi invariant mass distribution for exclusive B-->KomegaJ/psi decays. The results are obtained from a 253 fb(-1) data sample that contains 275 x 10(6) BB pairs that were collected near the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric energy e(+)e(-) collider. The statistical significance of the omegaJ/psi mass enhancement is estimated to be greater than 8sigma. 相似文献
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