共查询到20条相似文献,搜索用时 31 毫秒
1.
Padmavati Venkataraman Prasad Joshi Srinivasan P Venkatachalan Mani Muthalagi Harish S Parihar Karen S Kirschbaum Marvin K Schulte 《BMC biochemistry》2002,3(1):16-13
Background
Lerisetron, a competitive serotonin type 3 receptor (5-HT3R) antagonist, contains five functional groups capable of interacting with amino acids in the 5-HT3R binding site. Site directed mutagenesis studies of the 5-HT3AR have revealed several amino acids that are thought to form part of the binding domain of this receptor. The specific functional groups on the ligand that interact with these amino acids are, however, unknown. Using synthetic analogs of lerisetron as molecular probes in combination with site directed mutagenesis, we have identified some of these interactions and have proposed a model of the lerisetron binding site. 相似文献2.
Background
Electronic properties of amino acid side chains such as inductive and field effects have not been characterized in any detail. Quantum mechanics (QM) calculations and fundamental equations that account for substituent effects may provide insight into these important properties. PM3 analysis of electron distribution and polarizability was used to derive quantitative scales that describe steric factors, inductive effects, resonance effects, and field effects of amino acid side chains. 相似文献3.
Abstract
A classical convergent approach for the synthesis of the anticancer drug imatinib has been substantially improved. Imatinib was assembled by coupling the amine and carboxylic acid precursors by using N,N′-carbonyldiimidazole (CDI) as a condensing agent. Both intermediates have been synthesized by novel efficient methods. 相似文献4.
Background
Our prior solvent partition analysis, published in 1992, yielded pKa values for unconjugated bilirubin of about 8.1 and 8.4, but these results have been challenged and studies by other methods have suggested pKa values below 5.0. 相似文献5.
Background
Substance P (SP) is a peptide neurotransmitter found in central and peripheral nerves. SP is involved in the control of smooth muscle, inflammation and nociception. The amino acid sequence of SP is Arg-Pro-Lys-Pro-Gln-Gln-Phe-Phe-Gly-Leu-Met-NH2. Five different forms of fluorescently labeled SP have recently been synthesized, in which Alexa 488, BODIPY Fl, fluorescein, Oregon Green 488 or tetramethylrhodamine has been covalently linked to SP at Lys3. Here, these novel analogs are characterized as to their ligand binding, receptor activation and fluorescence labeling properties. 相似文献6.
Gabriela Flores-Ramírez Manuel Rivera Alfredo Morales-Pablos Joel Osuna Xavier Soberón Paul Gaytán 《BMC chemical biology》2007,7(1):1
Background
The effect of single and multiple amino acid substitutions in the green fluorescent protein (GFP) from Aequorea victoria has been extensively explored, yielding several proteins of diverse spectral properties. However, the role of amino acid deletions in this protein -as with most proteins- is still unknown, due to the technical difficulties involved in generating combinatorial in-phase amino acid deletions on a target region. 相似文献7.
Darren Greetham Jill Vickerstaff Daniel Shenton Gabriel G Perrone Ian W Dawes Chris M Grant 《BMC biochemistry》2010,11(1):3
Background
Protein-SH groups are amongst the most easily oxidized residues in proteins, but irreversible oxidation can be prevented by protein glutathionylation, in which protein-SH groups form mixed disulphides with glutathione. Glutaredoxins and thioredoxins are key oxidoreductases which have been implicated in regulating glutathionylation/deglutathionylation in diverse organisms. Glutaredoxins have been proposed to be the predominant deglutathionylase enzymes in many plant and mammalian species, whereas, thioredoxins have generally been thought to be relatively inefficient in deglutathionylation. 相似文献8.
Background
Sulfhydryl oxidases are flavin-dependent enzymes that catalyse the formation of de novo disulfide bonds from free thiol groups, with the reduction of molecular oxygen to hydrogen peroxide. Sulfhydryl oxidases have been investigated in the food industry to remove the burnt flavour of ultraheat-treated milk and are currently studied as potential crosslinking enzymes, aiming at strengthening wheat dough and improving the overall bread quality. 相似文献9.
Tatiana V Kolesnikova Brian A Mannion Fedor Berditchevski Martin E Hemler 《BMC biochemistry》2001,2(1):10
Background
The CD98 (4F2, FRP-1) is a widely expressed cell surface protein heterodimer composed of a glycosylated heavy chain and a non-glycosylated light chain. Originally described as a T cell activation antigen, it was later shown to function in amino acid transport, cell fusion and homotypic cell aggregation. Several lines of evidence suggest its functional interaction with integrins but the biochemical basis for this interaction has been unclear. 相似文献10.
Ami Lakdawala Minmin Wang Neysa Nevins Dennis C Liotta Danuta Rusinska-Roszak Marek Lozynski James P Snyder 《BMC chemical biology》2001,1(1):2-8
Background
Molecular mechanics (MM) and quantum chemical (QM) calculations are widely applied and powerful tools for the stereochemical and conformational investigations of molecules. The same methods have been extensively used to probe the conformational profile of Taxol (Figure 1) both in solution and at the β-tubulin protein binding site. 相似文献11.
Background
The mos proto-oncogene encodes a cytoplasmic serine/threonine-specific protein kinase with crucial function during meiotic cell division in vertebrates. Based on oncogenic amino acid substitutions the viral derivative, 124-v-Mos, displays constitutive protein kinase activity and functions independent of unknown upstream effectors of mos protein kinase. We have utilized this property of 124-v-Mos and screened for novel mos substrates in immunocomplex kinase assays in vitro. 相似文献12.
Background
A lot of effort has been focused on the integration of nanorods/nanowire as building blocks into three-dimensional (3D) complex superstructures. But, the development of simple and effective methods for creating novel assemblies of self-supported patterns of hierarchical architectures to designed materials using a suitable chemical method is important to technology and remains an attractive, but elusive goal. 相似文献13.
Background
The acetylation of the core histone NH2-terminal tails is catalyzed by histone acetyltransferases. Histone acetyltransferases can be classified into two distinct groups (type A and B) on the basis of cellular localization and substrate specificity. Type B histone acetyltransferases, originally defined as cytoplasmic enzymes that acetylate free histones, have been proposed to play a role in the assembly of chromatin through the acetylation of newly synthesized histones H3 and H4. To date, the only type B histone acetyltransferase activities identified are specific for histone H4. 相似文献14.
Background
Apolipoprotein B-100 (apo B-100) stands as one of the largest proteins in humans. Its large size of 4536 amino acids hampers the production of X-ray diffraction quality crystals and hinders in-solution NMR analysis, and thus necessitates a domain-based approach for the structural characterization of the multi-domain full-length apo B. 相似文献15.
Ośmiałowski Borys Kolehmainen Erkki Gawinecki Ryszard Kauppinen Reijo Koivukorpi Juha Valkonen Arto 《Structural chemistry》2010,21(5):1061-1067
Abstract
Association constants of 2,6-bis(alkylcarbonylamino)pyridines (alkyl = methyl or ethyl) and their perfluoroalkyl analogues with succin- and maleimide as well as with 2,2′-dipyridylamine (complementary DAD and ADA hydrogen bonding motifs are responsible for formation of the associates) have been determined by NMR titrations and quantum chemical calculations. Interactions of 2,6-bis(alkylcarbonylamino)pyridines with imides differ by character from these of perfluoroalkyl analogues. Such large difference was not observed for the 2,2′-dipyridylamine associates. Since fluorine atoms cause carbonylamino groups to be stronger hydrogen bond donors, perfluorinated species of this type were found to be more stable. Single crystal X-ray structures of 2,6-bis(trifluoromethylcarbonylamino)pyridine and 2,6-bis(pentafluoroethylcarbonylamino)pyridine have been also determined. 相似文献16.
Background
1,3-Diphenylpropenones (chalcones) are well known for their diverse array of bioactivities. Hydroxyl group substituted chalcones are the main precursor in the synthesis of flavonoids. Till date various methods have been developed for the synthesis of these very interesting molecules. Continuing our efforts for the development of simple, eco-friendly and cost-effective methodologies, we report here a solvent free condensation of aryl ketones and aldehydes using iodine impregnated alumina under microwave activation. This new protocol has been applied to a variety of substituted aryl carbonyls with excellent yield of substituted 1,3-diphenylpropenones. 相似文献17.
We have prepared novel monolithic-type highly cross-linked solid supports having surface amino group using a copolymerization
method of functional monomers and cross-linking monomer. From the view point of controlled surface functionalities, we have
firstly certified and proved quantitative determination methods of the surface amino groups to utilize and evaluate those
solid supports prepared as affinity resins. We utilized a typical titration method and ninhydrin method that have been effectively
utilized for quantitative determination of primary amine and amino acid. The ninhydrin method was calibrated using octylamine
as a standard compound (R
2 = 0.998) and proved applicability for the quantitative determination of other primary amines. A commercially available solid
support, Affigel, was able to be quantitatively evaluated only by the ninhydrin method, while Toyopearl afforded just compatible
amino group density to the value certified by the manufacturer only through titration method. The obtained incompatible results
using both determination methods have been unclear at this moment. On the other hand, both determination methods afforded
compatible amino group density of the prepared solid support. The obtained value was up to 126 μmol/ml, which was 94% of the
calculated theoretical value based on the feed composition. The results suggested surface-concentrated introduction of amino
groups. Based on the determination methods, especially ninhydrin method, we prepared the monolithic-type solid supports having
various densities of surface amino groups and proved quantitative and surface-concentrated introduction of amino groups. Those
amino groups were able to react with a relatively large ligand molecule, methotrexate, quantitatively and also with controlled
density. The obtained results strongly suggest that the novel monolithic-type solid supports have possible advantages when
we utilize those as affinity resins for target peptide analyses. 相似文献
18.
《Rapid communications in mass spectrometry : RCM》2018,32(5):373-379
Rationale
For radiocarbon results to be accurate, samples must be free of contaminating carbon. Sample pre‐treatment using a high‐performance liquid chromatography (HPLC) approach has been developed at the Oxford Radiocarbon Accelerator Unit (ORAU) as an alternative to conventional methods for dating heavily contaminated bones. This approach isolates hydroxyproline from bone collagen, enabling a purified bone‐specific fraction to then be radiocarbon dated by accelerator mass spectrometry (AMS).Methods
Using semi‐preparative chromatography and non‐carbon‐based eluents, this technique enables the separation of underivatised amino acids liberated by hydrolysis of extracted bone collagen. A particular focus has been the isolation of hydroxyproline for single‐compound AMS dating since this amino acid is one of the main contributors to the total amount of carbon in mammalian collagen. Our previous approach, involving a carbon‐free aqueous mobile phase, required a two‐step separation using two different chromatographic columns.Results
This paper reports significant improvements that have been recently made to the method to enable faster semi‐preparative separation of hydroxyproline from bone collagen, making the method more suitable for routine radiocarbon dating of contaminated and/or poorly preserved bone samples by AMS. All steps of the procedure, from the collagen extraction to the correction of the AMS data, are described.Conclusions
The modifications to the hardware and to the method itself have reduced significantly the time required for the preparation of each sample. This makes it easier for other radiocarbon facilities to implement and use this approach as a routine method for preparing contaminated bone samples.19.
Majid Vaezzadeh Mohammad Reza Saeedi Tirdad Barghi Mohammad Reza Sadeghi 《Chemistry Central journal》2007,1(1):22
Background
In recent years scientists have been trying both to increase the efficiency of solar cells, whilst at the same time reducing dimensions and costs. Increases in efficiency have been brought about by implanting carbon nanotubes onto the surface of solar cells in order to reduce the reflection of sunrays, as well as through the insertion of polymeric arrays into the intrinsic layer for charge separation. 相似文献20.
Silmar A. do Monte Elizete Ventura Tamires F. da Costa Sidney R. de Santana 《Structural chemistry》2011,22(3):497-507