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在合适的结晶条件下 ,从含Cr无氨培养基中生长的固氮菌 (AzotobactervinelandiiLipmann)突变种UW3 中纯化出的CrFe蛋白可从溶液中析出深棕色斜四棱柱晶体 ,晶体最大的两条对角线长度分别可达 0 .2 5mm和 0 .12mm。PEG 80 0 0、MgCl2 、NaCl、Tris和Hepes缓冲液的浓度及结晶方法等对该蛋白的出晶率、晶核数目、晶体大小和质量都有明显影响。CrFe蛋白结晶所需的上述化合物的最适浓度与在Mn中生长的固氮菌突变种UW3 的MnFe蛋白和缺失nifZ固氮菌突变种的ΔnifZMoFe蛋白结晶所需的最适浓度有所不同。结果表明 ,该蛋白晶体可能为CrFe蛋白的晶体 相似文献
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棕色固氮菌(Azotobacter vinelandii Lipmann)突变种UW3能在无Mo的无氨培养基中固氮生长,低浓度的Mn对UW3突变种生长有促进作用,从在Mn中生长的UW3菌体中分离得到的部分纯固氮酶组分Ⅰ蛋白含量有Mn和Fe原子(Fe/Mo/Mn为10.41:0.19:1.00)并有OP MoFe蛋白一半的还原乙炔和质子的活性。这种蛋白的吸收光谱和圆二色谱与MoFe蛋白存在明显的差异,含Mn蛋白的亚基分子量都与MoFe蛋白的α亚基相近。初步结果表明,这种含Mn蛋白可胡是一种固氮酶组分Ⅰ蛋白。 相似文献
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Tzaban S Friedlander G Schonberger O Horonchik L Yedidia Y Shaked G Gabizon R Taraboulos A 《Biochemistry》2002,41(42):12868-12875
The pathological prion protein PrP(Sc) is the only known component of the infectious prion. In cells infected with prions, PrP(Sc) is formed posttranslationally by the refolding of the benign cell surface glycoprotein PrP(C) into an aberrant conformation. The two PrP isoforms possess very different properties, as PrP(Sc) has a protease-resistant core, forms very large amyloidic aggregates in detergents, and is only weakly immunoreactive in its native form. We now show that prion-infected rodent brains and cultured cells contain previously unrecognized protease-sensitive PrP(Sc) varieties. In both ionic (Sarkosyl) and nonionic (n-octyl beta-D-glucopyranoside) detergents, the novel protease-sensitive PrP(Sc) species formed aggregates as small as 600 kDa, as measured by gel filtration. The denaturation dependence of PrP(Sc) immunoreactivity correlated with the size of the aggregate. The small PrP(Sc) aggregates described here are consistent with the previous demonstration of scrapie infectivity in brain fractions with a sedimentation coefficient as small as 40 S [Prusiner et al. (1980) J. Neurochem. 35, 574-582]. Our results demonstrate for the first time that prion-infected tissues contain protease-sensitive PrP(Sc) molecules that form low MW aggregates. Whether these new PrP(Sc) species play a role in the biogenesis or the pathogenesis of prions remains to be established. 相似文献
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We have isolated the delta-globin gene of the New-World spider monkey,
Ateles geoffroyi, and compared its nucleotide sequence with those of other
primate delta- and beta-globin genes. Among primate delta-globin genes, the
rate of nonsynonymous substitutions is much less than the rate of
synonymous substitutions. This suggests that primate delta- globin genes
may remain under evolutionary conservation, perhaps because hemoglobin A2
has an as yet unknown physiological importance.
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Giselle?L?Ferrari Jefferson?LB?Marques Rajiv?A?Gandhi Simon?R?Heller Fábio?K?Schneider Solomon?Tesfaye Humberto?R?GambaEmail author 《Biomedical engineering online》2010,9(1):26
Background
Autonomic neuropathy is a common and serious complication of diabetes. Early detection is essential to enable appropriate interventional therapy and management. Dynamic pupillometry has been proposed as a simpler and more sensitive tool to detect subclinical autonomic dysfunction. The aim of this study was to investigate pupil responsiveness in diabetic subjects with and without cardiovascular autonomic neuropathy (CAN) using dynamic pupillometry in two sets of experiments. 相似文献8.
一种新的肝细胞生成素(HPO)转录本及其生物学活性 总被引:3,自引:1,他引:2
利用 5′RACE技术从人胎肝组织中分离一种新形式的肝细胞生成素 (HPO 2 0 5 )cDNA ,其编码蛋白质氨基酸序列的N端较已报道的人肝细胞生成素HPO(hepatopoietin)多 80个氨基酸 ,推测其蛋白质分子量为 2 3kD。RT PCR检测HPOmRNA在多种肝癌细胞中表达 ,Western印迹可检测到 2 3kDHPO 2 0 5表达 ,表明此种形式HPO在自然状态下存在。将构建的HPO 2 0 5真核表达载体转染入COS 7细胞 ,其表达蛋白质能够刺激HepG2肝癌细胞DNA合成 ;将HPO 2 0 5、HPO和荷空表达载体分别转染入低水平表达HPO的Bel 740 2肝癌细胞株 ,发现HPO 2 0 5比HPO具有较强的激活MAPK磷酸化的活性。细胞周期分析稳定转染HPO 2 0 5 ,HPO细胞的增殖周期也支持这一结论。这些结果表明HPO 2 0 5具有刺激肝源性细胞增殖的活性 ,并提示HPO 2 0 5可能较HPO有更强的生物学活性 相似文献
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Robert C. Holman Ermias D. Belay Krista Y. Christensen Ryan A. Maddox Arialdi M. Minino Arianne M. Folkema Dana L. Haberling Teresa A. Hammett Kenneth D. Kochanek James J. Sejvar Lawrence B. Schonberger 《PloS one》2010,5(1)
Background
Prion diseases are a family of rare, progressive, neurodegenerative disorders that affect humans and animals. The most common form of human prion disease, Creutzfeldt-Jakob disease (CJD), occurs worldwide. Variant CJD (vCJD), a recently emerged human prion disease, is a zoonotic foodborne disorder that occurs almost exclusively in countries with outbreaks of bovine spongiform encephalopathy.This study describes the occurrence and epidemiology of CJD and vCJD in the United States.Methodology/Principal Findings
Analysis of CJD and vCJD deaths using death certificates of US residents for 1979–2006, and those identified through other surveillance mechanisms during 1996–2008. Since CJD is invariably fatal and illness duration is usually less than one year, the CJD incidence is estimated as the death rate. During 1979 through 2006, an estimated 6,917 deaths with CJD as a cause of death were reported in the United States, an annual average of approximately 247 deaths (range 172–304 deaths). The average annual age-adjusted incidence for CJD was 0.97 per 1,000,000 persons. Most (61.8%) of the CJD deaths occurred among persons ≥65 years of age for an average annual incidence of 4.8 per 1,000,000 persons in this population. Most deaths were among whites (94.6%); the age-adjusted incidence for whites was 2.7 times higher than that for blacks (1.04 and 0.40, respectively). Three patients who died since 2004 were reported with vCJD; epidemiologic evidence indicated that their infection was acquired outside of the United States.Conclusion/Significance
Surveillance continues to show an annual CJD incidence rate of about 1 case per 1,000,000 persons and marked differences in CJD rates by age and race in the United States. Ongoing surveillance remains important for monitoring the stability of the CJD incidence rates, and detecting occurrences of vCJD and possibly other novel prion diseases in the United States. 相似文献10.
Silvio Notari Francisco J. Moleres Stephen B. Hunter Ermias D. Belay Lawrence B. Schonberger Ignazio Cali Piero Parchi Wun-Ju Shieh Paul Brown Sherif Zaki Wen-Quan Zou Pierluigi Gambetti 《PloS one》2010,5(1)