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1.
Background
Recent studies point to a great diversity of non-ribosomal peptide synthesis systems with major roles in amino acid and co-factor biosynthesis, secondary metabolism, and post-translational modifications of proteins by peptide tags. The least studied of these systems are those utilizing tRNAs or aminoacyl-tRNA synthetases (AAtRS) in non-ribosomal peptide ligation. 相似文献2.
Raj K. Singh Mary F. Ruh Thomas S. Ruh 《Biochimica et Biophysica Acta (BBA)/General Subjects》1984,800(1):33-40
In the present study we investigated the binding characteristics of estrogen and antiestrogen-receptor complexes to rabbit uterine chromatin. Activated or nonactivated estrogen receptors were partially purified by DEAE-cellulose chromatography using low (1 mM) or high (10 mM) concentrations of sodium molybdate. Activated [3H]estradiol-receptor complexes showed enhanced binding to chromatin acceptor sites unmasked by 1 M, 4 M and 6 M guanidine hydrochloride. We also examined the chromatin-binding characteristics of the estrogen receptors when bound by the high-affinity triphenylethylene antiestrogen, H1285. The acceptor site activity for the [3H]H1285-receptor complexes was markedly decreased at sites unmasked by 4 M and 6 M guanidine hydrochloride. Further, the nonactivated receptor complexes showed very low binding to deproteinized chromatin. The estrogen-receptor chromatin-acceptor sites were tissue specific and saturable. These chromatin acceptor sites differ in their affinity and capacity (number of binding sites per cell) for the estrogen- and antiestrogen-receptor complexes. Thus, we suggest that the differences in the physiological and physicochemical properties of estrogens and antiestrogens may be related to their differential interaction with uterine chromatin subfractions. 相似文献
3.
Shashank Hambarde Chi-Lin Tsai Raj K. Pandita Albino Bacolla Anirban Maitra Vijay Charaka Clayton R. Hunt Rakesh Kumar Oliver Limbo Remy Le Meur Walter J. Chazin Susan E. Tsutakawa Paul Russell Katharina Schlacher Tej K. Pandita John A. Tainer 《Molecular cell》2021,81(14):2989-3006.e9
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4.
To investigate the influence of vasomotor tone and vessel compliance on pulmonary segmental vascular resistance, we determined the longitudinal distribution of vascular pressures in 15 isolated blood perfused lungs of newborn lambs. We measured pulmonary arterial and left atrial pressures and by micropuncture the pressures in 20- to 80-micron-diam subpleural arterioles and venules, both before and after paralyzing the vasculature with papaverine hydrochloride. In five lungs we also determined the microvascular pressure profile during reverse perfusion. In lungs with baseline vasomotor tone, approximately 32% of the total pressure drop was in arteries, approximately 32% in microvessels, and approximately 36% in veins. With elimination of vasomotor tone, arterial and venous resistances decreased to one-fifth and one-half of base-line values, respectively, indicating that vasomotor tone contributed mainly toward arterial resistance. During reverse perfusion, the pressure drop in veins was similar to that in arteries during forward perfusion, suggesting that the compliance of arteries and veins is comparable. We conclude that vascular tone and compliance are important factors that determine the distribution of segmental vascular resistance in lungs of the newborn. 相似文献
5.
6.
Background
Ubiquitin (Ub)-mediated signaling is one of the hallmarks of all eukaryotes. Prokaryotic homologs of Ub (ThiS and MoaD) and E1 ligases have been studied in relation to sulfur incorporation reactions in thiamine and molybdenum/tungsten cofactor biosynthesis. However, there is no evidence for entire protein modification systems with Ub-like proteins and deconjugation by deubiquitinating enzymes in prokaryotes. Hence, the evolutionary assembly of the eukaryotic Ub-signaling apparatus remains unclear. 相似文献7.
Significant differences were observed in GAG metabolism of S. digitata and one of its intermediate vectors, C. quinquefasciatus. Distribution of different components such as hyaluronic acid, heparin-sulphate, chondroitin-4-sulphate, chondroitin-6-sulphate, dermatan sulphate and heparin was comparable in both. However, there were quantitative differences; the difference was marked in the activity of enzymes of GAG metabolism in presence and absence of diethylcarbamazine (DEC) a known antifilarial drug. While the activities of beta-galactosidase and beta-N-acetyl glucosaminidase of S. digitata systems showed an inhibition of 96.5 and 92.6% respectively, in the Culex systems they showed an inhibition of 93.3% and an activation of 18% respectively. The differences clearly indicate the existence of basic differences in GAG metabolism of vector and parasite. 相似文献
8.
9.
Mamoru Koketsu Lekh Raj Juneja Hiroshi Kawanami Mujo Kim Takehiko Yamamoto 《Glycoconjugate journal》1992,9(2):70-74
Egg yolk, a large proportion of the egg, was studied for the preparation ofN-acetylneuraminic acid (Neu5Ac). The delipidated hen egg yolk (DEY; 500 kg containing 0.2% w/w, Neu5Ac) was hydrolysed with HCl (pH 1.4) at 80 °C and neutralized with NaOH (pH 6.0). The mixture was filtered and electrodialysed until the conductivity was 240 µS cm–1. The filtrate was applied on a column of Dowex HCR-W2 (20–50 mesh), followed by a column of Dowex 1-X8 (200–400 mesh). The latter column was washed with water, and then eluted with a linear gradient of HCO2H (0–2m). The eluates containing Neu5Ac were concentrated using a reverse osmosis membrane and, finally, rotary evaporated at 40 °C. The residue was then lyophilized to yield 500 g Neu5Ac. The purity of Neu5Ac was >98% (TBA method). HPLC, NMR spectroscopy and TLC chromatography of the product obtained from the DEY showed that Neu5Ac was the sole derivative present in egg yolk. The DEY, a byproduct from egg processing plants, was found to be an excellent source for the large-scale preparation of Neu5Ac.Abbreviations Neu5Ac
N-acetylneuraminic acid
- Neu5Gc
N-glycolylneuraminic acid
- DEY
delipidated egg yolk
- HPLC
high performance liquid chromatography
- TLC
thin layer chromatography
- NMR
nuclear magnetic resonance
- IR
infrared spectroscopy
Presented at the 11th International Symposium on Glycoconjugates, Toronto, Canada. 相似文献
10.
Constantin G. Ioannides Bryan Fisk Barbara Tomasovic Raj Pandita Bharat B. Aggarwal Ralph S. Freedman 《Cancer immunology, immunotherapy : CII》1992,35(2):83-91
Summary We have recently reported that autologous tumor-specific cytotoxic T lymphocyte (CTL) lines and clones can be developed from lymphocytes infiltrating ovarian malignant ascites (TAL). In this study, we investigated the biological effects of tumor necrosis factor (TNF) in the induction, expansion, long-term proliferation and lytic function of CD8+ TAL. TNF up-regulated the IL-2 receptor (IL-2R) chain (Tac antigen) on the surface of CD3+ CD8+ CD4– TAL, enhanced the proliferation of autologous tumor-specific CTL, and potentiated their lytic function in long-term cultures. Furthermore, in the induction and expansion phase of CD8+ TAL, the presence of TNF was associated with a selective increase in CD8+ IL-2R+ (Tac+) cells, and subsequent decrease in CD4+ IL-2R+ (Tac+) cells. These results suggest that the observed facilitation of the outgrowth of CD8+ cells in TAL cultures may be due, at least in part, to the up-regulation of IL-2R, and indicate the usefulness of TNF in the analysis of signalling in autologous tumor-reactive CTL. 相似文献