排序方式: 共有30条查询结果,搜索用时 0 毫秒
11.
12.
13.
The large N-linked oligosaccharides released from Schizosaccharomyces pombe
by endo-beta-N-acetylglucosaminidase H were examined to determine how the
negatively chargedpyruvylated galactoses present (Gemmill,T.R., and
Trimble,R.B., 1996, J. Biol. Chem ., 271, 25945-25949) were attached to the
oligosaccharide chains. Binding of biotinylated human serum amyloid P and
peanut agglutinin to native and depyruvylated S.pombe glycoproteins,
respectively, indicated that the pyruvylated epitope was likely to be in
the beta configuration. Examination by high- field 1H NMR of whole glycans
and a disaccharide fragment released from them on partial acid hydrolysis
showed that the pyruvylated galactose species was in fact beta1,3-linked to
a second galactose, and this occurred an average of five to six times on
nominal Gal57Man64GlcNAc N- glycans. The pyruvate-2,(4,6)Gal-beta1,3Gal
epitope is chemically similar to acetaldehyde-Galbeta1,3Gal groups found on
the glycoproteins from Paramyxovirus-infected bovine kidney cells (Prehm,
P., Scheid,A. and Choppin,P.W. ,1979, J. Biol. Chem ., 254, 9669-9677). The
1:1 stoichiometry between pyruvate and beta-linked galactose in these
S.pombe glycans indicates that either pyruvate addition to terminal
beta1,3Gal is highly efficient or that pyruvylated Gal is transferred en
bloc to alpha1,2-linked Gal residues in theN-linked chains. In
contradiction to many galactomannan-producing fungi, which add substantial
amounts of Gal in the furanose form to their glycoproteins, all detectable
Gal in the large S.pombe galactomannans is in the pyranose form, as found
in higher eukaryotes. The current work shows that the S.pombe outer chain
structure is a poly-alpha1,6Man backbone 2- O-substituted with either Gal
or the pyruvylated galactobiose and contains little alpha1,2-linked or
2-O-substituted Man. This is in contrast to the S. cerevisiae outer chain,
which is poly-alpha1,6Man substituted with alpha1,2-linked Man sidechains
(Ballou,C.E. ,1990, Methods Enzymol , 185, 440-470).
相似文献
14.
Lotus corniculatus nodulation specificity is changed by the presence of a soybean lectin gene 总被引:5,自引:0,他引:5 下载免费PDF全文
Plant lectins have been implicated as playing an important role in mediating recognition and specificity in the Rhizobium-legume nitrogen-fixing symbiosis. To test this hypothesis, we introduced the soybean lectin gene Le1 either behind its own promoter or behind the cauliflower mosaic virus 35S promoter into Lotus corniculatus, which is nodulated by R. loti. We found that nodulelike outgrowths developed on transgenic L. corniculatus plant roots in response to Bradyrhizobium japonicum, which nodulates soybean and not Lotus spp. Soybean lectin was properly targeted to L. corniculatus root hairs, and although infection threads formed, they aborted in epidermal or hypodermal cells. Mutation of the lectin sugar binding site abolished infection thread formation and nodulation. Incubation of bradyrhizobia in the nodulation (nod) gene-inducing flavonoid genistein increased the number of nodulelike outgrowths on transgenic L. corniculatus roots. Studies of bacterial mutants, however, suggest that a component of the exopolysaccharide surface of B. japonicum, rather than Nod factor, is required for extension of host range to the transgenic L. corniculatus plants. 相似文献
15.
OBJECTIVES: The present study was carried out to determine the effect of chromium(VI) on the status of plasma lipid peroxidation and erythrocyte antioxidant enzymes in workers exposed to chromium during chromium plating process. METHODS: Fifty subjects working in chromium plating process formed the study group. An equal number of age-sex matched subjects working in administrative units formed the control group. The control subjects were residing in the same city but away from the work place of study group subjects. Urinary chromium levels were determined by using a graphite furnace atomic absorption spectrophotometer. The plasma lipid peroxidation and erythrocyte antioxidant enzymes were determined by using spectrophotmetric methods. RESULTS: A significant increase of plasma lipid peroxidation and a significant decrease of superoxide dismutase and glutathione peroxidase levels were noted in the study group as compared with the controls. The level of plasma lipid peroxidation was positively and erythrocyte antioxidant enzymes were negatively and significantly correlated with chromium levels in urine. Multiple regression analysis was assessed the oxidative stress associated with chromium and life style confounding factors such as BMI, coffee, tea, alcohol and smoking. The multiple regression analysis showed that the urine chromium levels >10 micro g/g of creatinine, smoking, consumption of green vegetables and BMI variables were significantly associated with the levels of oxidative stress. CONCLUSION: The results show that the increased plasma lipid peroxidation and decreased antioxidant enzymes (superoxide dismutase and glutathione peroxidase) observed in chromium-exposed workers could be used as biomarkers of oxidative stress. 相似文献
16.
17.
Piyali Sabui Sadhucharan Mallick Kshitij RB Singh Arunadevi Natarajan Ranjana Verma Jay Singh Ravindra Pratap Singh 《Luminescence》2023,38(7):1047-1063
Food safety and quality are among the most significant and prevalent research areas worldwide. The fabrication of appropriate technical procedures or devices for the recognition of hazardous features in foods is essential to safeguard food materials. In the recent era, developing high-performance sensors based on carbon nanomaterial for food safety investigation has made noteworthy progress. Hence this review briefly highlights the different detection approaches (colorimetric sensor, fluorescence sensor, surface-enhanced Raman scattering, surface plasmon resonance, chemiluminescence, and electroluminescence), functional carbon nanomaterials with various dimensions (quantum dots, graphene quantum dots) and detection mechanisms. Further, this review emphasizes the assimilation of carbon nanomaterials with optical sensors to identify multiple contaminants in food products. The insights of carbon-based nanomaterials optical sensors for pesticides and insecticides, toxic metals, antibiotics, microorganisms, and mycotoxins detection are described in detail. Finally, the opportunities and future perspectives of nanomaterials-based optical analytical approaches for detecting various food contaminants are discussed. 相似文献
18.
MOTIVATION: Recently, we described a Maximum Weighted Matching (MWM) method
for RNA structure prediction. The MWM method is capable of detecting
pseudoknots and other tertiary base-pairing interactions in a
computationally efficient manner (Cary and Stormo, Proceedings of the Third
International Conference on Intelligent Systems for Molecular Biology, pp.
75-80, 1995). Here we report on the results of our efforts to improve the
MWM method's predictive accuracy, and show how the method can be extended
to detect base interactions formerly inaccessible to automated RNA modeling
techniques. RESULTS: Improved performance in MWM structure prediction was
achieved in two ways. First, new ways of calculating base pair likelihoods
have been developed. These allow experimental data and combined statistical
and thermodynamic information to be used by the program. Second, accuracy
was improved by developing techniques for filtering out spurious base pairs
predicted by the MWM program. We also demonstrate here a means by which the
MWM folding method may be used to detect the presence of base triples in
RNAs. AVAILABILITY: http://www.cshl.org/mzhanglab/tabaska/j axpage. html
CONTACT: tabaska@cshl.org
相似文献
19.
20.
Uric acid (UA) is a blood and urine component obtained as a metabolic by-product of purine nucleotides. Abnormalities in UA metabolism cause crystal deposition as monosodium urate and lead to various diseases such as gout, hyperuricemia, Lesch–Nyhan syndrome, etc. Monitoring these diseases requires a rapid, sensitive, selective, and portable detection approach. Therefore, this study demonstrates the hydrothermal synthesis of CuFe2O4/reduced graphene oxide (rGO) nanocomposite for selective detection of UA. After the nanocomposite synthesis, characterization was performed by X-ray diffraction spectroscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, UV–visible spectrometry, atomic force spectroscopy, scanning electron microscopy, and electrochemical analysis. Furthermore, from the electrochemical analysis using cyclic voltammetry (CV), kinetic studies were carried out by varying the scan rate to obtain the diffusion coefficient, surface concentration, and rate of charge transfer to achieve a calibration curve that indicates the quasi reversible nature of the fabricated electrode with a linear regression coefficient of oxidation (R2: 0.9992) and reduction (R2: 0.9971) peaks. Moreover, the fabricated nonenzymatic amperometric sensor to detect UA with a linearity (R2: 0.9989) of 1–400 μM was highly sensitive (2.75 × 10−4 mAμM−1 cm−2) and had a lower limit of detection (0.01231 μM) at pH 7.5 in phosphate-buffered saline solution. Therefore, the CuFe2O4/rGO/ITO-based nonenzymatic sensor could detect interfering agents and spiked real bovine serum samples with higher sensitivity and selectivity for UA detection. 相似文献