排序方式: 共有17条查询结果,搜索用时 46 毫秒
1.
Ronald K. Russell Richard A. Rampulla Caroline E. van Nievelt Dieter H. Klaubert 《Journal of heterocyclic chemistry》1990,27(6):1761-1770
The synthesis of thieno[4,3,2-de] tricyclic compounds is described. The N-1 alkylation of I produced the alkanoic ester precursors. After hydrolysis, the corresponding carboxylic acids were cyclized to the title compounds II . This cyclization step was accomplished with 1:10 phosphorus pentoxide-methanesulfonic acid. The ketones II were further modified to introduce additional functionality onto this novel tricyclic ring system. 相似文献
2.
Zhou W Shultz JW Murphy N Hawkins EM Bernad L Good T Moothart L Frackman S Klaubert DH Bulleit RF Wood KV 《Chemical communications (Cambridge, England)》2006,(44):4620-4622
New highly sensitive latent bioluminescent luciferin substrates were designed and synthesized for monitoring mammalian glutathione S-transferase (GST) and Schistosoma japonicum enzyme activities. 相似文献
3.
ter Steege DH Smits M de Lange CA Westwood NP Peel JB Visscher L 《Faraday discussions》2000,(115):259-69; discussion 303-30
A (2 + 1) one-colour resonance-enhanced multiphoton ionisation study is carried out on the C 2 sigma- state of the ClO radical in the one-photon energy range 29,500-31,250 cm-1. The ClO radical is produced by one-photon photolysis of ClO2 employing 359.2 nm photons derived from a separate laser. In this way a significant concentration of vibrationally excited ClO in its spin-orbit split X 2 pi omega (omega = 3/2 or 1/2) electronic ground state is produced. In addition to mass-resolved excitation spectra, kinetic-energy resolved photoelectron spectra for the X 3 sigma-(v+)<--C 2 sigma-(v' = 3-5) transitions are measured. These transitions are not completely Frank-Condon diagonal, and indicate a decrease in bond length on removal of the Rydberg electron from the C 2 sigma- state. In addition to an unambiguous assignment of the C 2 sigma- state, valuable information is obtained on the degree of vibrational excitation with which the nascent ClO radical is formed in the photolysis of ClO2. Analysis of the photoelectron spectra is supported by Franck-Condon calculations based on potential energy curves either from experimental spectroscopic parameters, or obtained by theoretical ab initio methods. 相似文献
4.
Zhou W Valley MP Shultz J Hawkins EM Bernad L Good T Good D Riss TL Klaubert DH Wood KV 《Journal of the American Chemical Society》2006,128(10):3122-3123
Novel bioluminogenic substrates were designed for probing monoamine oxidase (MAO) activity based on a simple and effective beta-elimination strategy. By modifying the amino group and the central core of luciferin derivatives, we have developed a series of substrates useful for assays of MAO A or B, or both. One of these substrates, exhibiting low Km values and high signal-to-background ratios with both isozymes, was shown to accurately measure the Ki values of known MAO inhibitors. This substrate is a key component in the development of a highly sensitive homogeneous MAO assay for high-throughput screening (HTS) of compounds in drug discovery and for monitoring MAO activity in complex biological systems. This design strategy should be applicable to fluorogenic MAO substrates and could broaden the structural requirements of substrates for other enzyme assays. 相似文献
5.
The design, fabrication, and testing of photoelastic models of double-lap, multiple-pin connectors are discussed. Interest
is in the stresses in the inner laps. These stresses are determined by constructing models with photoelastic inner laps and
transparent-acrylic outer laps. The connectors have two pins, in tandem, parallel to the load direction. A photoelastic-isotropic
point is shown to permit the evaluation of load sharing between the two pins. A numerical scheme, utilizing the isochromatic-
and isoclinic-photoelastic data and a finite-difference representation of the planestress equilibrium equations, is used to
compute the stresses around the two pins. Representative stress distributions and stress-concentration factors are shown. 相似文献
6.
Catherine Paradis-Bleau Adrian Lloyd François Sanschagrin Tom Clarke Ann Blewett Timothy DH Bugg Roger C Levesque 《BMC biochemistry》2008,9(1):33
Background
To develop antibacterial agents having novel modes of action against bacterial cell wall biosynthesis, we targeted the essential MurF enzyme of the antibiotic resistant pathogen Pseudomonas aeruginosa. MurF catalyzes the formation of a peptide bond between D-Alanyl-D-Alanine (D-Ala-D-Ala) and the cell wall precursor uridine 5'-diphosphoryl N-acetylmuramoyl-L-alanyl-D-glutamyl-meso-diaminopimelic acid (UDP-MurNAc-Ala-Glu-meso-A2pm) with the concomitant hydrolysis of ATP to ADP and inorganic phosphate, yielding UDP-N-acetylmuramyl-pentapeptide. As MurF acts on a dipeptide, we exploited a phage display approach to identify peptide ligands having high binding affinities for the enzyme. 相似文献7.
A novel acidotropic pH indicator and its potential application in labeling acidic organelles of live cells. 总被引:7,自引:0,他引:7
BACKGROUND: Ratio imaging has received intensive attention in the past few decades. The growing potential of ratio imaging is significantly limited, however, by the lack of appropriate fluorescent probes, for acidic organelles in particular. The classic fluorescent dyes (such as fluoresceins, rhodamines and coumarins) are not suitable for studying acidic organelles (such as lysosomes) because their fluorescence is significantly decreased under neutral or acidic conditions. This has motivated us to develop probes that can be used in ratio imaging that are strongly fluorescent even in acidic media. RESULTS: The compound 2-(4-pyridyl)-5-((4-(2-dimethylaminoethyl-aminocarbamoyl) methoxy)phenyl)oxazole (PDMPO) was prepared and characterized as a new acidotropic dual-excitation and dual-emission pH indicator. It emits intense yellow fluorescence at lower pH and gives intense blue fluorescence at higher pH. This unique pH-dependent fluorescence property was readily explored to selectively stain lysosomes and to determine the pH of the organelle in an emission-ratio-imaging mode. PDMPO is selectively localized to lysosomes and exhibits a pH-dependent dual excitation and emission. CONCLUSIONS: PDMPO selectively labels acidic organelles (such as lysosomes) of live cells and the two distinct emission peaks can be used to monitor the pH fluctuations of live cells in ratio measurements. Additionally, the very large Stokes shift and excellent photostability of PDMPO make the compound an ideal fluorescent acidotropic probe. The unique fluorescence properties of PDMPO might give researchers a new tool with which to study acidic organelles of live cells. 相似文献
8.
A useful one-pot procedure for preparing certain novel 8-subsituted guanosine derivatives from 7-allyl-8-thioxoguanosine (2b) has been developed. 相似文献
9.
10.
Dieter H. Klaubert Stanley C. Bell Thomas W. Pattison 《Journal of heterocyclic chemistry》1985,22(2):333-336
A three step synthesis of 5H-tetrazolo[5,1-c][1,4]benzodiazepin-11-ones 8a-d via the reaction of a substituted benzyl azide and ethyl cyanoformate is described. The derived lactams are converted to the corresponding 11-thiones 9a-d and, through the S-methylated derivatives, to the 11-amino analogs 11a-f. All of the described compounds are representatives of a novel ring system. 相似文献