Sheng wu hua xue yu sheng wu wu li xue bao Acta biochimica et biophysica Sinica最新文献

Calpain is a calcium-activated protease and has two ubiquitously distributed mammalian isoforms, namely calpain 1 (calpain I, mu-calpain and CAPN1) and calpain 2 (calpain II, m-calpain and CAPN2). Calpains regulate the function of many proteins by limited proteolysis. To determine the nature of different subtypes of calpain on degradation of microtubule-associated protein tau, the rat cortex extracts were incubated with 0.2 mmol/L, 1 mmol/L, 3 mmol/L and 5 mmol/L of CaCl(2 )for 15 min at 37 degrees C, respectively, and it was found that Ca(2+) treatment at concentrations 1-5 mmol/L led to significant proteolysis of the tau protein and this degradation was blocked by calpain inhibitor, calpeptin. In addition, when the extracts containing 1 mmol/L CaCl(2 )were treated with mu-calpain inhibitor (0.05 micromol/L of calpastatin) or m-calpain inhibitor (100 micromol/L calpain inhibitor IV) or both, the Ca(2+)-induced degradation of tau protein was blocked to about 8.6% 92.5% and 97.8% compared with the group with 1 mmol/L CaCl(2), respectively. These data suggest that both mu-calpain and m-calpain in brain cortex extracts are activated by Ca(2+) and both of them degraded tau protein, although, m-calpain plays a more important role in proteolysis of the tau protein.

A three-dimensional image of a living cell is helpful for cell secretion study. In this report, the three-dimensional fluorescence deconvolution microscopy for observing living cells was studied, because this technique can obtain a quick three-dimensional imaging with minimal fluorescence quenching and cytotoxicity for living cell observation. The property of three-dimensional point spread function (PSF) of imaging system was analyzed. The relationship between experimental and theoretical PSF was illustrated, and the theoretical PSF was proved that it could reflect the principle of imaging system with NA 1.65 objective in use. Three-dimensional deconvolution algorithm in this report was proved effective by well-defined three-dimensional specimens. Furthermore, the rat pancreatic beta cell secretory vesicles labeled by acridine orange was observed by using this technique. Results showed that the blurring induced by out-of-focus light was removed by the deconvolution algorithm effectively, under current experiment conditions (with NA 1.65 objective) the experimental PSF approximated the theoretical PSF very well, and deconvolved living cell images exhibited the spatial distribution of the secretory vesicles clearly.

To evaluate the effects of cysteine-SH-directed regents on the redox status, structure and function of human heat shock transcription factor 1 (hHSF1), treatment in vitro of hHSF1 with 0.3 0.5 mmol/L oxidizing reagent diamide (DM) and treatment in vivo of HeLa cells with 1 mmol/L buthionine sulfoximine (BSO), an inhibitor of gamma-glutamylcysteine synthetase, promoted the formation of a compact, intramolecularly disulfide-crosslinked, stable monomeric form of ox-hHSF1, and blocked the trimerization and activation of HSF1. The effects of diamine were dose-dependent and readily could be completely reversed by adding 0.4 0.5 mmol/L reducing reagent dithiothreitol (DTT) to the samples prior to gel electrophoresis. Computer modeling of the alpha-helical coiled-coil domains of the HSF1 monomer and trimer showed that the alignment of the N- and C-terminal hydrophobic repeats of HSF1 monomer could bring C(3)(Cys(153))close to C(4) and C(5)(Cys(373) and Cys(378), respectively), in positions permissible for disulfide bond formation under appropriate experimental conditions. The results suggest that redox-dependent thiol-disulfide exchange can provide a mechanism for regulation the conformation and activity of hHSF1.

Nitric oxide (NO) was speculated to play an important role in the pathophysiology of cerebral ischemia. In this study, the effect of oxygen-glucose deprivation (OGD) on the cellular production of NO was investigated in cultured hippocampal neurons. Intracellular Ca(2+) was also detected as its closely relationship with NO. The generation of NO and changes in intracellular Ca(2+) were evaluated using confocal laser scanning microscopy with diaminofluorescein diacetate (DAF-2 DA), an NO probe, and Fluo-3, a Ca(2+) probe respectively. Extracellular glutamate level was also measured by HPLC with fluorescence detection. Results showed that OGD induced an increase in NO production and intracellular Ca(2+) concentration ([Ca(2+)](i)), the rise of DAF-2 and Fluo-3 fluorescence intensity was about 160% and 270% respectively; an increase of about 100% in glutamate level was observed after 20 min of OGD. NMDA inhibitor MK-801 significantly reduced the OGD-induced elevation of [Ca(2+)](i) and NO, DAF-2 and Fluo-3 fluorescence intensity uptake was inhibited by 69% and 74% respectively. The increase in NO production was also attenuated by extracellular Ca(2+) elimination and calmodulin (CaM) antagonist trifluoperazine dose-dependently. These results indicated that NO production increased during oxygen-glucose deprivation, and was greatly modulated by glutamate release, intracellular Ca(2+) change and Ca(2+)-CaM pathway.

Metallothionein-3(MT-3), also known as growth inhibitory factor (GIF), is predominantly expressed in central nervous system (CNS). It belongs to the family of metallothionein(MT) but has several unique properties that are not shared by other family members such as MT-1/MT-2. In the past few years, MT-3 had been postulated to be a multipurpose protein which could play important neuromodulatory and neuroprotective roles in CNS besides the common roles of MTs. However, the primary function of MT-3 and the mechanism underlying its multiple functions were not elucidated so far. In present study, human neuroblastoma cell line SH-SY5Y was employed to study the overall cellular protein changes induced by transient transfection of MT-3 gene, based on comparative proteome analysis. Averagely about 750 spots were visualized by Coomassie staining in one 2D gel, in which 17 proteins were shown to display significant and reproducible changes by semiquantitative analysis with ImageMaster 2D Elite software. Among them, 12 proteins were up-regulated while other 5 proteins were down-regulated. Using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, 10 proteins were further identified to be zinc finger protein, glutamate transporter, and enhancer protein, etc., which were involved in several important pathways regulating the functions of central nervous system. The results showed that MT-3 might exert its unique functions by regulating the expression of these proteins.

The genome of wheat rosette stunt virus (WRSV), a plant rhabdovirus, is a single negative strand RNA. It encodes five viral structural proteins: the glycoprotein (G), the matrix protein (M), the nucleocapsid protein (N), the large protein (L) and the non?structural protein (NS), which was later proved to be a viral structural protein too and existed in a variety of phosphorylation forms in case of vascular stomatitis virus (VSV). In this paper we demonstrated that NS protein of WRSV, either bound with the viral nucleocapsid or expressed in bacteria could be in vitro phosphorylated in presence of viral nucleocapsid. We concluded that the NS protein of WRSV was a phosphorylated protein and it might exist in both phosphorylated and dephosphorylated forms in virions. Our results excluded the possibility that the NS protein could be autophosphorylated. The L protein, the major component of viral RNA dependent RNA polymerase is associated with the protein kinase for phosphorylation of NS protein.

Penicillin G Acylas (PGA) of Providencia rettgeri (ATCC 25599) was evolved using a modified DNA family shuffling method. The identity of pga genes from Escherichia coli, Kluyvera citrophila and Providencia rettgeri ranges from 62.5% to 96.9%. The pga genes from above three species were recombined and shuffled to create interspecies pga gene fusion libraries. By substituting assembled chimaeras for corresponding region of pETPPGA, different recombinants were constructed and expressed in E. coli JM109(DE3). Mutants with obvious beta-lactam synthetic activity were selected from the plates and the ratios of synthesis to hydrolysis (S/H) were determined subsequently. It was shown that the primary structures of selected positives exhibited significant diversity among each library. The best mutant possessed 40% higher synthetic activity than the wild type enzyme of PrPGA. It was further proved in this study that the domain of alpha subunit contributed much more to improve the specific activity of synthesis. Results showed a recombinant PGA with higher synthetic activity was acquired by the method of DNA shuffling.

Cases of the life-threatening respiratory disease with no identified cause (designated as "severe acute respiratory syndrome", SARS, in March 2003) were first reported in late 2002 from Guangdong Province, China; they were followed by reports from about other 30 countries (or regions) such as Vietnam, Singapore, Thailand, Hong Kong (China), Canada, and USA etc. Because of its ongoing epidemic and high death rate, SARS has shined an intense spotlight all over the world. The World Health Organization (WHO) has promptly established a network of international laboratories consisting of 13 members around the 10 countries to facilitate the identification of the causative agent of SARS. A novel coronavirus, SARS virus, fulfilling all of Koch's postulates was announced to be the primary aetiological agent of SARS on April 16 by WHO shortly after the Canadian scientists released the full-length genome sequence of SARS virus (Tor2) on April 12. China is now facing a formidable task to fight SARS. In this article, we present a brief summary on the biological characteristics of coronavirus with its associated diseases, and make some suggestions on how to curb this outbreak and how to cure SARS disease based on the potential targets of this novel virus.

BR-D96N was a genetically mutated product of bacteriorhodopsin (BR) with obvious improved photochromic effect. Compared with the wild type BR, BR-D96N had a lifetime of M state prolonged to 5 min, showing obvious saturation absorption and lower light intensity in saturation absorption (0.4 mW/cm(2)). In case of holographic recording, dynamic grating was recorded in the BR-D96N film, its characteristic parameter was not light exposure energy but light intensity. The writing time of the holographic grating depended on the recording light intensity. The higher the recording light intensity, the faster the grating builds up. Under a weak reconstruction light, the recording light intensity resulting in maximal diffraction efficiency was consistent with the saturation absorption intensity. The reconstruction light could partly erase the grating. With lower intensity of reconstruction light, higher diffraction efficiency (1.8%) could be reached, but the diffraction intensity was not high. To get highest diffraction intensity, a properly high intensity of reconstruction light was needed (80 microW/cm(2)). The result of these experiments showed that holographic images could be recorded on the BR-D96N film.

ASB-8 is a new member of the human ankyrin repeat and SOCS box containing protein family (ASB). This report deals with the expression of ASB-8 protein in lung carcinoma tissue, as well as its biological effect on the proliferation and growth of lung cancer cell line SPC-A1. ASB-8 was expressed in pT7-450 expression vector, and an anti-ASB-8 rabbit polyclonal antibody was prepared. The expression of ASB-8 protein in lung carcinoma tissue was detected using immunohistochemistry. The growth characteristics of the lung adenocarcinoma SPC-A1 cells expressing either exogenous ASB-8 or ASB-8 SB (SOCS box-deficient) was studied by both in vitro cell growth curve and in vivo nude mouse tumor formation assay. Immunohistochemical staining detected positive reaction of 96.8% (30/31) showing that ASB-8 was highly expressed in lung cancer tissues; however, the expression of ASB-8 was lower, or even no expression in noncancerous lung tissues. Significant growth inhibition was observed in SPC-A1 cell line expressing ASB-8 SB on day 4 and persisted to day 6, compared with mock transfected cells (P<0.01). No difference in the growth properties was observed between ASB-8 and mock transfected cells. In vivo study also showed that tumor formation of ASB-8 SB expressing cells was significantly inhibited as compared with that of the control group (P<0.01). Therefore, ASB-8 may play an important role in growth and proliferation of lung cancer, possibly as positive regulator.