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151.
Bartlett S Beddard GS Jackson RM Kayser V Kilner C Leach A Nelson A Oledzki PR Parker P Reid GD Warriner SL 《Journal of the American Chemical Society》2005,127(33):11699-11708
The conformation of a bisindolylmaleimide may be controlled by the size of a macrocyclic ring in which it is constrained. A range of techniques were used to demonstrate that the tether controls both the ratio of the two limiting conformers (syn and anti) in solution and the extent of conjugation between the maleimide and indole rings. Screening the conformationally diverse bisindolylmaleimides against a panel of protein kinases allowed their ATP binding sites to be compared using a chemical approach which, like sequence alignment, does not require detailed structural information. This approach lead to the conclusion that several AGC group protein kinases (including PKCalpha, PKCbeta, MSK1, p70 S6K, PDK-1, and MAPKAP-K1alpha) may be best inhibited by bisindolylmaleimides which adopt a compressed approximately C2-symmetric anti conformation; in constrast, GSK3beta may be best inhibited by bisindolylmaleimides whose ground state is a distorted syn conformation. It is concluded that PDK-1, whose structure has been determined by X-ray crystallography, and its mutants, may serve as particularly useful surrogates for the study of PKC inhibitors. 相似文献
152.
We present the results of an extensive single-crystal neutron scattering study of the ferroelastic phase transition in [Formula: see text]. This material has previously been demonstrated to undergo a continuous loss of long-range order at its ferroelastic transition, which is the phenomenon known as lattice melting. We show that our data are consistent with a special form of lattice melting where the long-range order appears to be destroyed in a two-dimensional sense, but is preserved in the third dimension. 相似文献
153.
Linestrengths have been obtained for methanol based on matrix elements of the dipole moment operator evaluated in a set of torsion-rotation eigenfunctions. The latter were obtained from the parameters and effective Hamiltonian giving the best spectral fit available for a data set containing J = 20, K = 14, and upsilont = 1 microwave and far infrared transitions. The dipole moment function was represented as a Fourier expansion in the torsional angle gamma. Values for the permanent components μa and μb were obtained from experiment; values for their cos 3gamma variation and for the sin 3gamma variation of μc were obtained from quantum chemistry molecular orbital calculations. The approach described allows calculation of the linestrength for any transition which satisfies the general selection rule A1 left and right arrow A2 or E left and right arrow E. A complete set of such linestrengths for all methanol torsion-rotation transitions involving levels with J = 22, K = 14, and upsilont = 2, and with intensities and frequencies above the rather small cutoff limits of 10(-6) D2 and 1 kHz, respectively, together with individual contributions from the permanent and gamma-varying dipole moment components, have been tabulated and are available on request (ftp.monash.edu.au/pub/chem/1998a). Copyright 1999 Academic Press. 相似文献
154.
We present here the first quantum mechanical/molecular mechanics (QM/MM) studies of taurine/alpha-ketoglutarate dioxygenase (TauD) enzymes. Our studies are focused on the chemical properties of the oxo-iron species and the effect of the protein environment on its structural and electronic behavior. Although the active site region of TauD is very polar with many key hydrogen bonding interactions and salt bridges, the actual effect of the protein environment on the ordering and relative energies of the possible spin state structures is found to be quite small. Optimized geometries are very close to ones observed with density functional theory models that did not take the protein environment into consideration. The calculations show that protonation of the histidine ligands of iron is essential to reproduce the correct electronic representations of the enzyme. Hydroxylation studies of taurine by the oxo-iron active species predict that it is a very efficient catalyst that reacts with substrates via low reaction barriers. 相似文献
155.
Mathematics Support Centres are to be found in various formsin the majority of UK higher education institutions. They havebeen established in order to ease widespread and serious difficultiesthat a significant number of students have with mathematics,particularly at the school–university transition. Theyusually offer mathematics and/or statistics support to studentsacross the full range of disciplines studied. Anecdotal evidencesuggests that those students who make good use of such centresare not just those who struggle with mathematics. Many frequentusers are quite competent and simply want to do better. Thestudy reported here describes and analyses data from one cohortof engineering students. A novel aspect is the quantificationof the proportion of support centre visitors who fall into these,and other, categories. We conclude of the cohort in the study,mathematics support has improved the pass rate by 3%. Of thefailures, about half (4% of the sample total) could well havepassed had they attended the mathematics support centre regularly.Furthermore, the majority of those attending were not studentswho were in danger of failing. This has important implicationsnot only for the design of mathematics support provision, butalso for the performance of the high fliers. The methodologyoffers one way tackling the difficult task of evaluating theeffectiveness of mathematics support initiatives. 相似文献
156.
New neutral gauge bosons (Z' 's) are predicted by many models of physics beyond the standard electroweak theory. It is possible that a Z' will be discovered by the Large Hadron Collider program. The next step would be to measure its properties to identify the underlying theory that gave rise to the Z'. Heavy quarks have the unique property that they can be identified in the final states. In this Letter we demonstrate that measuring Z' decays to b- and t-quark final states can act as an effective means of discriminating between models with extra gauge bosons. 相似文献
157.
Guanhua Lu Akop Yepremyan Simon Godfrey Corinne Mohr Mathias Herrlein Michael A. Brook 《Journal of polymer science. Part A, Polymer chemistry》2021,59(17):1935-1941
The aza-Michael reaction is proving to be a practical, catalyst free method by which a variety of polymers, including silicones, can be cured. However, its adoption may be compromised by slow cure rates; for many applications is it not practical to accelerate cure by heating. OH groups on the amine, acrylate partner or solvent are known to lead to accelerated rates of aza-Michael reactions. The impact of the location of OH groups on reaction partners is demonstrated using both small molecules and small molecules plus telechelic silicones. While all OH groups are shown to increase reaction rates, a special enhancement is provided by β-hydroxyalkyl acrylate esters, which have significantly higher rates of reaction than simple acrylates per se, and yet higher reactivities in hydroxylic media. Using this motif, in the absence of solvents, silicone elastomer cure based on the β-hydroxyalkyl acrylate motif is facile and complete in less than 30 min at room temperature. 相似文献
158.
Luana Mifsud Buhagiar Carmel Sammut Yana Chircop Kersty Axisa Nicolette Sammut Bartolo Janis Vella Szijj Anthony Serracino Inglott Godfrey LaFerla 《Biomedical chromatography : BMC》2019,33(12)
Amitriptyline (AMI) has been in use for decades in treating depression and more recently for the management of neuropathic pain. A highly sensitive and specific LC–tandem mass spectrometry method was developed for simultaneous determination of AMI, its active metabolite nortriptyline (NOR) and their hydroxy‐metabolites in human serum, using deuterated AMI and NOR as internal standards. The isobaric E‐10‐hydroxyamitriptyline (E‐OH AMI), Z‐10‐hydroxyamitriptyline (Z‐OH AMI), E‐10‐hydroxynortriptyline (E‐OH NOR) and Z‐10‐hydroxynortriptyline (Z‐OH NOR), together with their parent compounds, were separated on an ACE C18 column using a simple protein precipitation method, followed by dilution and analysis using positive electrospray ionisation with multiple reaction monitoring. The total run time was 6 min with elution of E‐OH AMI, E‐OH NOR, Z‐OH AMI, Z‐OH NOR, AMI (+ deuterated AMI) and NOR (+ deuterated NOR) at 1.21, 1.28, 1.66, 1.71, 2.50 and 2.59 min, respectively. The method was validated in human serum with a lower limit of quantitation of 0.5 ng/mL for all analytes. A linear response function was established for the range of concentrations 0.5–400 ng/mL (r2 > .999). The practical assay was applied on samples from patients on AMI, genotyped for CYP2C19 and CYP2D6, to understand the influence of metaboliser status and concomitant medication on therapeutic drug monitoring. 相似文献
159.
César A. Urbina-Blanco Safia Z. Jilani Isaiah R. Speight Michael J. Bojdys Tomislav Friščić J. Fraser Stoddart Toby L. Nelson James Mack Renã A. S. Robinson Emanuel A. Waddell Jodie L. Lutkenhaus Murrell Godfrey Martine I. Abboud Stephen O. Aderinto Damilola Aderohunmu Lučka Bibič João Borges Vy M. Dong Lori Ferrins Fun Man Fung Torsten John Felicia P. L. Lim Sarah L. Masters Dickson Mambwe Pall Thordarson Maria-Magdalena Titirici Gabriela D. Tormet-González Miriam M. Unterlass Austin Wadle Vivian W.-W. Yam Ying-Wei Yang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(42):18462-18466
160.
The European Physical Journal A - We report on the development and characterization of the first radioactive boron beams produced by the isotope mass separation online (ISOL) technique at... 相似文献