排序方式: 共有26条查询结果,搜索用时 734 毫秒
1.
Abstract Dibutylstannylene acetals, particularly those derived from terminal diols, were found to be oxidized regiospeeifically to α-hydroxyketones in good to excellent yield by N-bromosuccinimide. One of the products, 3-deoxy-l,2-O-isopropylidene-α-D-erythro hexofuranos-5-ulose (8), exists to about 20% in solution as a mixture of dimers. One of the dimers can be obtained as a solid and its structure was determined tentatively by a combination of NMR experiments and MM3 molecular mechanics calculations. 相似文献
2.
P J Artymiuk P A Bath H M Grindley C A Pepperrell A R Poirrette D W Rice D A Thorner D J Wild P Willett F H Allen 《Journal of chemical information and computer sciences》1992,32(6):617-630
This paper discusses algorithmic techniques for measuring the degree of similarity between pairs of three-dimensional (3-D) chemical molecules represented by interatomic distance matrices. A comparison of four methods for the calculation of 3-D structural similarity suggests that the most effective one is a procedure that identifies pairs of atoms, one from each of the molecules that are being compared, that lie at the center of geometrically-related volumes of 3-D space. This atom mapping method enables the calculation of a wide range of types of intermolecular similarity coefficient, including measures that are based on physicochemical data. Massively-parallel implementations of the method are discussed, using the AMT Distributed Array Processor, that achieve a substantial increase in performance when compared with a sequential implementation on a UNIX workstation. Current work involves the use of angular information and the extension of the method to field-based similarity searching. Similarity searching in 3-D macromolecules is effected by the use of a maximal common subgraph (MCS) isomorphism algorithm with a novel, graph-based representation of the tertiary structures of proteins. This algorithm is being used to identify similarities between the 3-D structures of proteins in the Brookhaven Protein Data Bank; its use is exemplified by searches involving the NAD-binding fold motif. 相似文献
3.
Wagner AM Fegley MW Warner JB Grindley CL Marotta NP Petersson EJ 《Journal of the American Chemical Society》2011,133(38):15139-15147
Methods for synthetically manipulating protein structure enable greater flexibility in the study of protein function. Previous characterization of the Escherichia coli aminoacyl tRNA transferase (AaT) has shown that it can modify the N-terminus of a protein with an amino acid from a tRNA or a synthetic oligonucleotide donor. Here, we demonstrate that AaT can efficiently use a minimal adenosine substrate, which can be synthesized in one to two steps from readily available starting materials. We have characterized the enzymatic activity of AaT with aminoacyl adenosyl donors and found that reaction products do not inhibit AaT. The use of adenosyl donors removes the substrate limitations imposed by the use of synthetases for tRNA charging and avoids the complex synthesis of an oligonucleotide donor. Thus, our AaT donors increase the potential substrate scope and reaction scale for N-terminal protein modification under conditions that maintain folding. 相似文献
4.
A. Köster B. Miczyska K. Miczyski A. Listowski J. Voss P. N. Bhargava K. V. Giri J. G. A. Griffiths K. Schmorl N. W. Romenski H. C. Eckstein H. S. Grindley T. S. Hamilton W. B. Nevens G. L. Clark J. L. Gring und Th. v. Fellenberg 《Fresenius' Journal of Analytical Chemistry》1938,113(3-4):140-144
Ohne Zusammenfassung 相似文献
5.
M. Leprince R. Lecoq Napoleone Passerini H. Wagner G. Schöler W. E. Joseph M. E. Slater H. S. Grindley H. C. Eckstein J. C. Ross Sigmund Hals Sverre Heggenhougen Erich Ewers C. J. Lintner G. Belschner O. Wenglein Dowzard H. Weller Syniewski F. Mach P. Lederle Honcamp Ries Ad. Beneschovsky Wilk Nördlinger Ralph M. Bohn Krauss A. Jentsch Tacke und E. Blanck 《Fresenius' Journal of Analytical Chemistry》1920,59(1):33-48
Ohne Zusammenfassung 相似文献
6.
Alan G. Gonçalves Diogo R. B. Ducatti T. Bruce Grindley M. Eugênia R. Duarte Miguel D. Noseda 《Journal of the American Society for Mass Spectrometry》2010,21(8):1404-1416
We have prepared a number of isomeric red seaweed galactan-derivative sulfated oligosaccharides to determine whether there
were diagnostic differences among the isomeric mass spectra obtained using ESI CID MS/MS (triple quadrupole instrument). Fragmentation
of the single or multicharged molecular ions from di-, tetra-, and hexasaccharides indicated that the relative positioning
of the sulfate groups and type of monosaccharide unit affect the rate of cleavage of the glycosidic bonds. We also performed
a comparative [M-Na]− fragmentation study of positional isomers of sulfated disaccharides that present all four monosulfation possibilities on
the galactopyranosidic ring. In this case, negative-ion ESI CID MS/MS approach gave diagnostic product ions from cross-ring
cleavages along with the same main B1 ion (from sulfated Galp), at m/z 241, for all isomers. The isomeric disaccharides were also submitted to increased spray energy conditions inducing in-source
fragmentation; preformed B1 ions were then fragmented to give similar product ions as those found in [M-Na]− analysis. Evaluation of the relative abundances mainly for cross-ring fragment ions at m/z 138, 139, 151, 153 allowed clear distinction among the members of the disaccharide series. The different ratios for m/z 151/153 ions were consistent with the predominance of m/z 153 being related to the cases when the bond involved in the cleavage process links a sulfated carbon. A quadrupole ion trap
instrument (MSn analysis) was also utilized to compare the results obtained with the triple quadrupole instrument. 相似文献
7.
A nonavalent glycodendrimer bearing terminal alpha-d-mannopyranoside units has been synthesized with a convergent approach. Terminal trivalent mannoside dendrons bearing p-halophenyl ethers were prepared by glycosylation of pentaerythritol derivatives having three 2-hydroxyethyl ether substituents. Two efficient routes were developed for the synthesis of the pentaerythritol-based core (17), which has three terminal propargyl ethers. Conditions were found under which the triple Sonogashira coupling reaction of the dendron and the tri-O-propargyl ether (17) proceeded efficiently. The product was deprotected and it and precursors were fully characterized by NMR spectroscopy and FT-ICR mass spectrometry. 相似文献
8.
M. Leprince R. Lecoq Napoleone Passerini H. Wagner G. Schöler W. E. Joseph M. E. Slater H. S. Grindley H. C. Eckstein J. C. Ross Sigmund Hals Sverre Heggenhougen Erich Ewers C. J. Lintner G. Belschner O. Wenglein Dowzard H. Weller Syniewski F. Mach P. Lederle Honcamp Ries Ad. Beneschovsky Wilk Nördlinger Ralph M. Bohn Krauss A. Jentsch Tacke E. Blanck 《Analytical and bioanalytical chemistry》1920,59(1):33-48
9.
10.
T.Bruce Grindley 《Tetrahedron letters》1982,23(17):1757-1760
The conformations of methyl, ethyl and isopropyl formate were shown to be present in equilibrium in a polar solvent with the conformations to significant (> 1% 230 K) but much lower extents than for t-butyl formate; rotational barriers for the former compounds are greaters. 相似文献