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排序方式: 共有105条查询结果,搜索用时 15 毫秒
81.
The acidic glycolipid fraction (AF) of the porcine, parasitic nematode,
Ascaris suum , consisted of two subfractions. The major component AF II
reacted with orcinol-sulfuric acid and molybdate, while the minor component
AF I gave a positive reaction with azure-A, a cationic dye specific for
sulfatides. Sugar constituent analysis, methanolysis, methylation analysis,
matrix-assisted laser desorption/ionization time- of-flight mass
spectrometry, liquid secondary-ion mass spectrometry, and gas-liquid
chromatography/mass spectrometry specified AF II to be an unusual
phosphoinositolglycosphingolipid (Galalpha1-Ins-P-1ceramide) and the minor
component AF I to be a 3-sulfogalactosylcerebroside (HSO3-
3Galss1-1ceramide). The ceramide moiety of both components consisted of
lignoceric (C24:0) and cerebronic (C24h:0) acids and mainly C17 iso-
branched sphingosine. Immunohistochemical localization studies of the
glycolipid-bound antigenic determinants with a polyclonal antiserum against
AF II and an anti-sulfatide monoclonal antibody against AF I revealed the
presence of the AF II-epitope in the intestine, whereas the AF I-epitope
was found in the hypodermis, contractile zone of somatic muscle cells and
the external musculature of the uterus. To our knowledge, this is the first
report of the presence of a sulfatide in an invertebrate.
相似文献
82.
83.
Di Cola E Waigh TA Trinick J Tskhovrebova L Houmeida A Pyckhout-Hintzen W Dewhurst C 《Biophysical journal》2005,88(6):4095-4106
The persistence length of titin from rabbit skeletal muscles was measured using a combination of static and dynamic light scattering, and neutron small angle scattering. Values of persistence length in the range 9-16 nm were found for titin-II, which corresponds to mainly physiologically inelastic A-band part of the protein, and for a proteolytic fragment with 100-nm contour length from the physiologically elastic I-band part. The ratio of the hydrodynamic radius to the static radius of gyration indicates that the proteins obey Gaussian statistics typical of a flexible polymer in a -solvent. Furthermore, measurements of the flexibility as a function of temperature demonstrate that titin-II and the I-band titin fragment experience a similar denaturation process; unfolding begins at 318 K and proceeds in two stages: an initial gradual 50% change in persistence length is followed by a sharp unwinding transition at 338 K. Complementary microrheology (video particle tracking) measurements indicate that the viscoelasticity in dilute solution behaves according to the Flory/Fox model, providing a value of the radius of gyration for titin-II (63 +/- 1 nm) in agreement with static light scattering and small angle neutron scattering results. 相似文献
84.
A dichloromethane extract of the aerial parts of Combretum albopunctatum Suesseng afforded five phenolic compounds-three known flavonoids and two novel cyclobutane chalcone dimers. The chemical structures were determined by standard spectroscopic techniques and the structure and relative stereochemistry of one chalcone dimer, rel-(1 alpha,2 beta)-di-(2,6-dimethoxy-4-hydroxy)-benzoyl-rel-(3 alpha,4 beta)-diphenylcyclobutane, were confirmed by single crystal X-ray diffraction. 相似文献
85.
Vanquelef E Amoros M Boustie J Lynch MA Waigh RD Duval O 《Journal of enzyme inhibition and medicinal chemistry》2004,19(6):481-487
The synthesis of benzo[c]phenanthridine alkaloid derivatives is described. In vitro antiviral activity against herpes simplex type 1 (HSV1) has been investigated. Contrary to the natural product fagaronine, which did not have any activity in the HSV1 antiviral tests, four 12-alkoxy derivatives showed good activity demonstrating the importance of the 12-substitution in the structure-activity relationships. 相似文献
86.
The phase transformations in starch during gelatinisation: a liquid crystalline approach 总被引:1,自引:0,他引:1
The analogy between starch and a chiral side-chain polymeric liquid crystal is examined in relation to the processes involved during gelatinisation. There are three important parameters for characterisation of the molecular phase behaviour of the amylopectin: the lamellar order parameter (psi), the orientational order parameter of the amylopectin double helices (phi), and the helicity of the sample (h, the helix/coil ratio, a measure of the helix-coil transition of the double helices). The coupling between the double helices and the backbone through the flexible spacers is affected dramatically by the water content and it is this factor which dictates the particular phase adopted by the amylopectin inside the starch granule as a function of temperature. SAXS, WAXS and 13C CP/MAS NMR are used to examine these phenomena in excess water. Furthermore, previous experimental evidence pertaining to the limiting water case is reviewed with respect to this new theoretical framework. 相似文献
87.
RD Calixto R Verlengia AH Crisp TB Carvalho MD Crepaldi AA Pereira AK Yamada GR da Mota CR Lopes 《Biology of sport / Institute of Sport》2014,31(4):289-294
This study aimed to compare the effects of different velocities of eccentric muscle actions on acute blood lactate and serum growth hormone (GH) concentrations following free weight bench press exercises performed by resistance-trained men. Sixteen healthy men were divided into two groups: slow eccentric velocity (SEV; n = 8) and fast eccentric velocity (FEV; n = 8). Both groups performed four sets of eight eccentric repetitions at an intensity of 70% of their one repetition maximum eccentric (1RMecc) test, with 2-minute rest intervals between sets. The eccentric velocity was controlled to 3 seconds per range of motion for SEV and 0.5 seconds for the FEV group. There was a significant difference (P < 0.001) in the kinetics of blood lactate removal (at 3, 6, 9, 15, and 20 min) and higher mean values for peak blood lactate (P = 0.001) for the SEV group (9.1 ± 0.5 mM) compared to the FEV group (6.1 ± 0.4 mM). Additionally, serum GH concentrations were significantly higher (P < 0.001) at 15 minutes after bench press exercise in the SEV group (1.7 ± 0.6 ng · mL−1) relative to the FEV group (0.1 ± 0.0 ng · mL−1). In conclusion, the velocity of eccentric muscle action influences acute responses following bench press exercises performed by resistance-trained men using a slow velocity resulting in a greater metabolic stress and hormone response. 相似文献
88.
89.
Hampshire AJ Khairallah H Khalaf AI Ebrahimabadi AH Waigh RD Suckling CJ Brown T Fox KR 《Bioorganic & medicinal chemistry letters》2006,16(13):3469-3474
We have used DNA footprinting and fluorescence melting experiments to study the sequence specific binding of an imidazole-containing isopropyl-substituted thiazole polyamide (thiazotropsin B) to DNA. While the parent compound (thiazotropsin A) binds to the hexanucleotide sequence ACTAGT, changing one of the N-methylpyrrole groups to N-methylimidazole changes the preferred binding sequence to (A/T)CGCG(T/A). Experiments with DNA fragments that contain variants of this sequence suggest that the ligand can also bind, with lower affinity, to sequences which differ from this by 1bp in any position. 相似文献
90.
Molecular cloning and characterization of an alpha1,3 fucosyltransferase, CEFT-1, from Caenorhabditis elegans 总被引:1,自引:1,他引:1
We report on the identification, molecular cloning, and characterization of
an alpha1,3 fucosyltransferase (alpha1,3FT) expressed by the nematode,
Caenorhabditis elegans . Although C. elegans glycoconjugates do not express
the Lewis x antigen Galbeta1-- >4[Fucalpha1-->3]GlcNAcbeta-->R,
detergent extracts of adult C.elegans contain an alpha1,3FT that can
fucosylate both nonsialylated and sialylated acceptor glycans to generate
the Lexand sialyl Lexantigens, as well as the lacdiNAc-containing acceptor
GalNAcbeta1-->4GlcNAcbeta1-- >R to generate GalNAcbeta1-->4
[Fucalpha1-->3]GlcNAcbeta1-->R. A search of the C.elegans genome
database revealed the existence of a gene with 20-23% overall identity to
all five cloned human alpha1,3FTs. The putative cDNA for the C.elegans
alpha1,3FT (CEFT-1) was amplified by PCR from a cDNA lambdaZAP library,
cloned, and sequenced. COS7 cells transiently transfected with cDNA
encoding CEFT-1 express the Lex, but not sLexantigen. The CEFT-1 in the
transfected cell extracts can synthesize Lex, but not sialyl Lex, using
exogenous acceptors. A second fucosyltransferase activity was detected in
extracts of C. elegans that transfers Fuc in alpha1,2 linkage to Gal
specifically on type-1 chains. The discovery of alpha-fucosyltransferases
in C. elegans opens the possibility of using this well-characterized
nematode as a model system for studying the role of fucosylated glycans in
the development and survival of C.elegans and possibly other helminths.
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