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排序方式: 共有1302条查询结果,搜索用时 31 毫秒
1.
The Multiskan spectrophotometric system and Coomassie brilliant blue G-250 protein-dye binding method have been used together to measure NaOH-solubilized protein in subcellular membrane fractions prepared from isolated rat adipose cells. Forty-eight samples can be read in duplicate within 1 min. Sucrose in concentrations up to 0.7 m interfere only moderately with the assay. A rapid and convenient method is, therefore, now available for multiple protein determinations following sucellular fractionation on sucrose gradients. 相似文献
2.
O Sonne 《Journal of biochemistry》1988,103(2):348-353
Making freshly isolated rat hepatocytes permeable by 0.4 g/liter digitonin doubled the number of binding sites for alpha 2-macroglobulin.trypsin complex without changing the affinity. Thus, digitonin unmasked a receptor pool, probably of intracellular origin. The total cellular binding capacity was measured in the presence of digitonin, the surface-exposed in its absence. Upon preincubation of the cells at 37 degrees C, the total cellular binding capacity for alpha 2-macroglobulin.trypsin decreased over a 2-h period to 0.26 of the initial value. By contrast, the surface-exposed binding capacity initially increased in response to a preincubation at 37 degrees C, reached after 20 min a peak value 1.74 times that at 0 time, followed by a decrease. Neither the increase in nor the loss of surface-exposed binding capacity was influenced by inhibitors of lysosomal functions, protein synthesis and glycosylation. Colchicine abolished the increase in surface-exposed binding capacity but not the disappearance. By contrast, phenylarsine oxide (inhibitor of endocytosis), N-ethylmaleimide, and phenylmethanesulphonyl fluoride inhibited the receptor loss, suggesting that the loss occurred by proteolysis. The insulin receptor concentration, studied in parallel, remained practically constant in the investigated period in the presence and absence of digitonin. Thus, the hepatic receptor for alpha 2-macroglobulin.protease complexes is regulated independently of other specialized plasma membrane proteins. 相似文献
3.
Kasper Stovgaard Christian Andreetta Jesper Ferkinghoff-Borg Thomas Hamelryck 《BMC bioinformatics》2010,11(1):429
Background
Genome sequencing projects have expanded the gap between the amount of known protein sequences and structures. The limitations of current high resolution structure determination methods make it unlikely that this gap will disappear in the near future. Small angle X-ray scattering (SAXS) is an established low resolution method for routinely determining the structure of proteins in solution. The purpose of this study is to develop a method for the efficient calculation of accurate SAXS curves from coarse-grained protein models. Such a method can for example be used to construct a likelihood function, which is paramount for structure determination based on statistical inference. 相似文献4.
5.
O Sonne 《Biochimica et biophysica acta》1987,927(1):106-111
More than 90% of the radioactivity associated with isolated rat adipocytes incubated with [TyrA14-125I]monoiodoinsulin represented at steady state iodoinsulin possessing full binding affinity. In contrast, about half of the radioactivity dissociating from the cells was [125I]monoiodotyrosine. The other half was of a molecular size similar to that of iodoinsulin as judged from gel-filtration chromatography. However, the descending limb of the 'insulin' peak (i.e., the smaller molecules) possessed a reduced binding activity compared with native iodoinsulin, material from the ascending limb, or a similar fraction isolated from dissociation medium from IM-9 lymphocytes, a cell type devoid of receptor-mediated insulin degradation. The cells, thus, release an intermediary degradation product. 相似文献
6.
Endogenous opioid peptides (EOP) and prior exercise may modulate the stimulatory effect of glucose on insulin secretion. To gain insights into these relationships, we studied male Wistar rats (187-245 g) during sustained hyperglycemia by use of the glucose clamp technique. Four groups of sedentary fed rats (n = 8/group) either ran (Ex) at 24 m/min, 0% grade, or rested (R) for 40 min. Thirty minutes after Ex or R, arterial blood glucose was elevated to and maintained at 11 mM for 2 h by a variable glucose infusion. At the start of Ex or R rats had saline (Sal) or naloxone (Nal, an opioid antagonist) intravenous infusions for 160 min (40 min Ex + 30 min R + 90 min of a 120-min glucose clamp). Steady-state glucose infusion rates (SSGIR) were approximately 55 mg.kg-1.min-1 at the start of the clamp and declined significantly over the 2nd h to approximately 45 mg.kg-1.min-1. No significant differences existed in SSGIR between groups. R-Sal and Ex-Sal groups did not differ in their insulin response to hyperglycemia. In contrast, when all groups were compared at the end of the Nal or Sal infusion, Ex-Nal had the lowest insulin concentration (749 +/- 174 pmol/l), whereas the R-Nal group had the highest (1,581 +/- 216 pmol/l, P less than 0.05). These data suggest a stimulatory role for EOP on insulin secretion that is expressed after a prior stress (Ex). Thus one function of exercise-induced activation of EOP may be to regulate insulin secretion in the immediate postexercise period. 相似文献
7.
Tina Pallesen Annette Vangsted Lars Drivsholm Henrik Clausen Jesper Zeuthen Håkan Wallin 《Glycoconjugate journal》1992,9(6):331-335
We here report an enzyme linked immunosorbent assay (ELISA) and a scintillation proximity assay (SPA) for detection of the ganglioside FucGM1 in sera from small cell lung cancer (SCLC) patients. The SPA was more sensitive and reproducible than the ELISA. In this assay, monoclonal antibodies specific for FucGM1 were bound to SPA particles and incubated with labelled FucGM1 and 100 µl test-serum overnight, and counted in a -counter. The sensitivity was 0.2 ng. Seven out of twenty sera from SCLC patients were positive, whereas none of twenty sera from healthy individuals were positive for FucGM1. The SPA was more sensitive than the previously reported HPTLC as well as a direct ELISA.Abbreviations MAb
monoclonal antibody
- SPA
scintillation proximity assay
- HPTLC
high performance thin layer chromatography
- SCLC
small cell lung cancer
- FucGM1
Fuc1-2Gal1-3GalNAc1-4(NeuAc2-3)-Gal1-4Glc1-1Cer
- ELISA
enzyme linked immunosorbent assay
- FCS
foetal calf serum
- PBS
phosphate buffered saline 相似文献
8.
9.
Ca2+ efflux from sarcoplasmic reticulum vesicles was studied by measurements of net Ca2+ uptake, 45Ca2+ flux and hydrolysis of energy-rich phosphate. The maximal Ca2+ uptake capacity (150–200 nmol/mg protein at pH 6.7, 10 mM MgCl2 and μ=0.26) was independent of the nature and concentration of the energy-donating substrate (ATP or carbamyl phosphate) and of temperature (15–35°C), suggesting coupling between influx and efflux of Ca2+. In the presence of high concentrations of ATP, this efflux of Ca2+ was much higher than the passive Ca2+ permeation, measured after ATP or Ca2+ depletion of the reaction medium. Ca2+ efflux was imperceptible at vesicle filling levels below 35–40 nmol Ca2+/mg protein, and uncorrelated to the inhibition of the Ca2+-ATPase by high intravesicular Ca2+ concentrations. Analysis of the data indicated that Ca2+ efflux under our conditions probably is associated with one of the Ca2+-ATPase partial reactions occurring after dephosphorylation, rather than with a reversal of the Ca2+ translocation step in the phosphorylated state of the enzyme. Furthermore, passive Ca2+ permeation may be concurrently reduced during the enzymatically active state. It is proposed that both Ca2+ efflux and passive Ca2+ permeation (Ca2+ outflow) proceed via the same channels which are closed (occluded) during part of the Ca2+-ATPase reaction cycle. 相似文献
10.
Comparison of the Action of Ampicillin and Benzylpenicillin on Enterococci In Vitro 总被引:1,自引:0,他引:1 下载免费PDF全文
The bactericidal activity of benzylpenicillin and ampicillin on 21 strains of enterococci was evaluated and compared to the activity of these drugs in combination with streptomycin (20 mug/ml). On a weight basis, ampicillin was about twice as effective as benzylpenicillin. Neither of the drugs was rapidly and completely bactericidal for any of the 21 strains of enterococci when used alone. The addition of streptomycin greatly enhanced the early bactericidal rate achieved with any given amount of either penicillin and permitted the elimination of viable organisms in vitro. These results suggest that, for the time being, combined antibiotic therapy might be desirable in enterococcus endocarditis and that ampicillin, although more effective than benzylpenicillin, should not be relied upon as a single drug in that disease. 相似文献