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31.
Two new acyl sucroses were isolated from the epigeal parts of Petunia nyctaginiflora Juss. (Solanaceae). Their structures were determined to be 2, 3, 4-tri (5-methylhexanoyl)-alpha-D-glucopyranosyl-beta-D-fructofuranoside (2) and 2, 3, 4-tri (6-methylheptanoyl)-alpha-D-glucopyranosyl-beta-D-fructofuranoside (4) on the basis of chemical and spectroscopic evidence. 相似文献
32.
Extraction of membrane proteins from a living cell surface using the atomic force microscope and covalent crosslinkers 总被引:1,自引:0,他引:1
The force curve mode of the atomic force microscope (AFM) was applied to extract intrinsic membrane proteins from the surface
of live cells using AFM tips modified by amino reactive bifunctional covalent crosslinkers. The modified AFM tips were individually
brought into brief contact with the living cell surface to form covalent bonds with cell surface molecules. The force curves
recorded during the detachment process from the cell surface were often characterized by an extension of a few hundred nanometers
followed mostly by a single step jump to the zero force level. Collection and analysis of the final rupture force revealed
that the most frequent force values (of the force) were in the range of 0.4–0.6 nN. The observed rupture force most likely
represented extraction events of intrinsic membrane proteins from the cell membrane because the rupture force of a covalent
crosslinking system was expected to be significantly larger than 1.0 nN, and the separation force of noncovalent ligand-receptor
pairs to be less than 0.2 nN, under similar experimental conditions. The transfer of cell surface proteins to the AFM tip
was verified by recording characteristic force curves of protein stretching between the AFM tips used on the cell surface
and a silicon surface modified with amino reactive bifunctional crosslinkers. This method will be a useful addition to bionanotechnological
research for the application of AFM. 相似文献
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35.
Summary Glucagon increased alanine amino transferase (AAT) activity in perfused rat liver by about 90% over control. Propranolol, the beta receptor antagonist, abolished the effect of glucagon on this enzyme. Well known beta receptor agonists like isoproterenol, norepinephrine and epinephrine also increased the enzyme activity under identical condition and the enhancement was similarly abolished by propranolol. These experiments suggest that the effect of glucagon on AAT was mediated through beta adrenergic receptor. However, the interesting observation was that phenylephrine, alpha receptor agonist and phenoxybenzamine and tolazoline, two alpha receptor antagonists, increased the AAT activity like glucagon in perfusion experiments and the effects of all these three agents were also abolished by propranolol. Glucagon, when perfused with phenoxybenzamine showed some additive effect. From all these results we are proposing that in our system phenoxybenzamine is acting as beta agonist although it is known to be an alpha antagonist. 相似文献
36.
Begum A Rahman MM Ogawa W Mizushima T Kuroda T Tsuchiya T 《Microbiology and immunology》2005,49(11):949-957
There are six putative genes for multidrug and toxic compound extrusion (MATE) family multidrug efflux pumps in the chromosome of Vibrio cholerae. We have so far analyzed two MATE family pumps in V. cholerae non-O1 NCTC4716. Here we cloned four remaining genes for putative MATE family efflux pumps by the PCR method from this microorganism and designated them as vcmB, vcmD, vcmH and vcmN. Each one of the four genes was introduced and expressed in the drug hypersusceptible host Escherichia coli KAM32 cells. We observed elevated MICs of multiple antimicrobial agents, such as fluoroquinolones, aminoglycosides, ethidium bromide and Hoechst 33342 in the transformants. Energydependent efflux of substrate was observed with the transformed cells. We found that efflux activities of VcmB, VcmD and VcmH were Na+-dependent, but that of VcmN was Na+-independent. Thus, all six of the MATE family multidrug efflux pumps of V. cholerae non-O1 have been characterized. We also found that all six genes were expressed in cells of V. cholerae non-O1. 相似文献
37.
Debnath Bhuniya Rajendra K. Kharul Atul Hajare Nadim Shaikh Sandeep Bhosale Sandip Balwe Fouzia Begum Siddhartha De Sonalee Athavankar Dhananjay Joshi Vamsi Madgula Kaushal Joshi Amol A. Raje Ashwinkumar V. Meru Amol Magdum Kasim A. Mookhtiar Rashmi Barbhaiya 《Bioorganic & medicinal chemistry letters》2019,29(2):238-243
Conceptual design and modification of urea moiety in chemotype PF-3845/04457845, the bench marking irreversible inhibitor of fatty acid amide hydrolase (FAAH), led to discovery of a novel nicotinamide-based lead 12a having reversible mechanism of action. Focused SAR around the pyridine heterocycle (Ar) in 12a (Tables 1 and 2) resulted into four shortlisted compounds, (?)-12a, (?)-12i, (?)-12l–m. The required (?)-enantiomers were obtained via diastereomeric resolution of a novel chiral dissymmetric intermediate 15. Based on comparative profile of FAAH potency, metabolic stability in liver microsome, liability of inhibiting major hCYP450 isoforms, rat PK, and brain penetration ability, two SAR optimized compounds, (?)-12l and (?)-12m, were selected for efficacy study in rat model of chemotherapy-induced peripheral neuropathy (CIPN). Both the compounds exhibited dose related antihyperalgesic effects, when treated with 3–30?mg/kg po for 7?days. The effects at 30?mg/kg are comparable to that of PF-04457845 (10?mg/kg) and Tramadol (40?mg/kg). 相似文献
38.
Using several model organisms it has been shown earlier that protein designability is related to contact density or fraction
of buried residues and influence protein evolutionary rates dramatically. Here, using Homo sapiens as a model organism, we have analyzed two main folding classes (all-α and all-β) to examine the factors affecting their evolutionary
rates. Since, secondary structures are the most fundamental components of the protein folding classes, we explored the effect
of protein secondary structure composition on evolution. Our results show that sheet and helix fractions exhibit positive
and negative correlations, respectively, with the rate of protein evolution. On dividing the secondary structure components
according to solvent accessibility, linear regression model identified two factors namely buried sheet fraction and relative
aggregation propensity. Both these factors together can explain about 13.4% variability in the rate of human protein evolution, while buried sheet
residues can alone account to 9.9% variability. 相似文献
39.
Gülay Bayramoğlu Meral Karakışla Begum Altıntaş Ayşegül U. Metin Mehmet Saçak M. Yakup Arıca 《Process Biochemistry》2009,44(8):880-885
Polyacylonitrile fibers (PAN) surfaces were modified with chemical polymerization of conductive polyaniline (PANI) in the presence of potassium dichromate as an oxidizing agent. The effect of aniline concentration on the grafting efficiency and on the electrical surface resistance of PAN/PANI composite fibers was investigated. The surface resistance of the conductive composite fibers in this work was found to be between 8.0 and 0.5 kΩ/cm. As the amount of grafted PANI increased on the PAN fibers the electrical resistance of composite fibers decreased. The PAN/PANI composite fibers were characterized by SEM and FTIR studies. Composite PAN/PANI fibers were used for reversible immobilization of invertase. The immobilization efficiency and the activity of the immobilized invertase (from 1.0 mg/mL invertase solution at pH 5.5) were increased with increasing PANI contents of the composite fibers. The maximum amount of immobilized enzyme onto composite fibers containing 2.0% PANI was about 76.6 mg/g. The optimum pH for the free enzyme was observed at 5.0. On the other hand, immobilized invertase yielded a broad optimum pH profile between pH 5.0 and 7.0. Immobilized invertase exhibited 83% of its original activity even after two months storage at 4 °C while the free enzyme showed only 7% of its initial activity. 相似文献
40.
Hasina Begum Jennifer E. Spindel Antonio Lalusin Teresita Borromeo Glenn Gregorio Jose Hernandez Parminder Virk Bertrand Collard Susan R. McCouch 《PloS one》2015,10(3)
Genome-wide association mapping studies (GWAS) are frequently used to detect QTL in diverse collections of crop germplasm, based on historic recombination events and linkage disequilibrium across the genome. Generally, diversity panels genotyped with high density SNP panels are utilized in order to assay a wide range of alleles and haplotypes and to monitor recombination breakpoints across the genome. By contrast, GWAS have not generally been performed in breeding populations. In this study we performed association mapping for 19 agronomic traits including yield and yield components in a breeding population of elite irrigated tropical rice breeding lines so that the results would be more directly applicable to breeding than those from a diversity panel. The population was genotyped with 71,710 SNPs using genotyping-by-sequencing (GBS), and GWAS performed with the explicit goal of expediting selection in the breeding program. Using this breeding panel we identified 52 QTL for 11 agronomic traits, including large effect QTLs for flowering time and grain length/grain width/grain-length-breadth ratio. We also identified haplotypes that can be used to select plants in our population for short stature (plant height), early flowering time, and high yield, and thus demonstrate the utility of association mapping in breeding populations for informing breeding decisions. We conclude by exploring how the newly identified significant SNPs and insights into the genetic architecture of these quantitative traits can be leveraged to build genomic-assisted selection models. 相似文献