Mutagenesis of Ser24 of Cytochrome b559 α Subunit Affects PSII Acitivies in Chlamydomonas reinhardtii

In order to study the functions of cytochrome b559 (Cyt b559) in photosystem two (PSII) activity, mutant S24F of Chlamydomonas reinhardtii was constructed using site directed mutagenesis, in which Serine24 (Ser24) locating downstream of Histidine23 (His23) in α subunit of Cyt b559 was replaced by Phenylalanine (Phe). Physiological and biochemical analysis showed that mutant S24F could be grown photoautotrophically or photoheterotrophically. However, their growth rate was slower either on HSM or TAP medium than that of the control; Analysis of PSII activity revealed that its oxygen evolution was about 71% of wild type (WT); The Photochemical efficiency of PSII (Fv/Fm) of S24F was reduced 0.23 compared with WT; S24F was more sensitive to strong light irradiance than the wild type; Furthermore, SDS-PAGE and Western-blotting analysis indicated that the expression levels of α subunit of Cyt b559, LHCII and PsbO of S24F were a little less than those of the wild type. Overall, these data suggests that Ser24 plays a significant role in making Cyt b559 structure maintain PSII complex activity of oxygen evolution although it is not directly bound to heme group.     

锰卟啉模拟细胞色素P-450催化环己烷单充氧的研究

合成了Mn(Ⅲ)-Mn(Ⅲ)单核和双核金属卟啉配合物，用元素分析、紫外可见光谱进行表征．研究了这些双核金属卟啉模拟细胞色素P-450催化环己烷单充氧作用及金属卟啉在2种反应体系中催化性能．对于催化活性随着2个金属卟啉之间碳链增长而增长，反应体系的改变引起催化活性的改变的规律与前面铁卟啉是一致的．但锰卟啉催化活性普遍高于其相应的铁卟啉，而选择性普遍低于铁卟啉．     

Mitochondrial cytochrome b sequence variations and phylogeny of the East Asian bagrid catfishes

The mitochondrial DNA cytochrome b gene was sequenced from 8 bagrid catfishes in China. Aligned with cytochrome b sequences from 9 bagrid catfishes in Japan, Korea and Russia retrieved from GenBank, and selected Silurus meridionalis, Liobagrus anguillicauda, Liobagrus reini and Phenacogrammus interruptus as outgroups, we constructed a matrix of 21 DNA sequences. The Kimura's two-parameter distances were calculated and molecular phylogenetic trees were constructed by using the maximum parsimony (MP) and neighbor-joining (NJ) methods. The results show that (i) there exist 3-bp deletions of mitochondrial cytochrome b gene compared with cypriniforms and characiforms; (ii) the molecular phylogenetic tree suggests that bagrid catfishes form a monophyletic group, and the genus Mystus is the earliest divergent in the East Asian bagrid catfishes, as well as the genus Pseudobagrus is a monophyletic group but the genus Pelteobagrus and Leiocassis are complicated; and (iii) the evolution rate of the East Asian bagrids mitochondrial cytochrome b gene is about 0.18%～0.30% sequence divergence per million years.     

AOT／异辛烷萃取猪心细胞色素C的方法研究初探

用５０ｍｍｏｌ／ＬＡＯＴ反胶团系统在添加０．１ｍｏｌ／ＬＫＣｌ，ｐＨ７．５条件下萃取了猪心糜粗提液（Ⅰ）、ｐＨ７．５沉淀杂质蛋白后的提取液的滤液（Ⅱ）、硫酸铵（５００ｇ／Ｌ）盐析除杂蛋白的清液透析液（Ⅲ）、硫酸矮（５０ｇ／Ｌ）除杂蛋白的滤液并透析除盐的溶液（Ⅳ）、细胞色素Ｃ的三氯乙酸的沉淀物的饱和硫酸铵溶液透析除盐细胞色素Ｃ溶液（Ⅴ）中的细胞色素Ｃ。用１ｍｏｌ／ＬＫＣｌ、ｐＨ１３．０的水溶液对萃取有机相中的细胞色素Ｃ进行反萃取获得细胞色素Ｃ溶液。结果显示，ＡＯＴ反胶团系统能够将细胞色素Ｃ从猪心提取液中萃取到有机相中，并经调节离子强度和ｐＨ值又能将细胞色素Ｃ从有机相中反萃取到水溶液中。其萃取效率（％）分别为８６．９、７８．１、６３．１、４３．１和６。     

阳离子对猪心细胞色素C的反胶团萃取的影响

在猪心提取液中添加阳离子的情况下，观察了ＡＯＴ／异辛烷反胶团对蛋白质和细胞色素Ｃ的萃取效果。结果表明：萃取分相以添加Ｍｇ（２＋）最好，其次分别为Ｎａ＋．Ｋ＋、Ｃａ（２＋）。在添加Ｍｇ（２＋）、Ｎａ＋，Ｃａ（２＋），Ｋ＋离子后，对蛋白质的萃取率分别为：５０．４％、３１．５％、２９．２％、２７．８％。在添加Ｍｇ（２＋），Ｎａ＋Ｋ＋离子时，对细胞色素的萃取率（以反萃取率表示）分别为４０．６％、３７．４％、＋３０．４％。     

Effects on the early development of the pearl sac by cytochrome c, yolk lecithin and polyvinyplyrro

Mantle pieces ofHyriopisis cumingii was treated by three kinds of solution, These mantle pieces were inserted together with paraffin nucleuses into the connective tissue of three groups ofHyriopisis cumingii. These operated animals were cultured in a pool for a month. Several pearl sacs were put out and immersed by Bouin's solution after every five days. Sections of each animals were made by histological method. Those without treatment were in a control group. Observations of these sections showed that cytochrome c and yolk lecithin have an accelerated roles on pearl sac development and pearl layer secretion. No effects on pearl sac development by polyvinyplyrrolidone (PVP). Zheng Junying:born in May, 1966, Lecturer     

The use of primary cultures of adult rat hepatocytes to study induction of enzymes and DNA synthesis: Effect of nafenopin and electroporation

Summary Primary cultures of adult rat hepatocytes maintained in a well-differentiated state, in a chemically defined medium containing 2% DMSO, have been utilized to study the effect of non-mutagenic hepatocarcinogens such as the peroxisome proliferator nafenopin. The parameters chosen in this in vitro system were those that paralleled the major in vivo effects of nafenopin on the liver, mainly: the proliferation of the endoplasmic reticulum and induction of cytochrome P-452, the proliferation of the peroxisome compartment and the induction of cyanide-insensitive -oxidation of fatty acids and the stimulation of liver growth as measured by the DNA synthetic activity of the hepatocytes.In this review, we also describe the morphology of hepatocyte cultures prepared from previously electroporated hepatocytes and the potential for the use of electroporation to introduce growth related genes into hepatocyte cells to study the mechanisms of hepatocyte growth at the molecular level. In addition we describe the formation of endoplasmic reticulum whorls in these cultures as a consequence of nafenopin treatment. Whorl formation by hepatotrophic chemicals has been previously shown to occur in vivo; in this report, it is described for the first time in vitro.     

Na_5SeV_5O_(18)·3H_2O对K562细胞线粒体凋亡和NF-κB/IκBα信号转导途径的影响

通过MTT比色法和Western blot法检测Na5SeV5O18.3H2O的抗肿瘤活性及作用机理.结果表明,Na5SeV5O18.3H2O(0.625~20 mg.L-1)能抑制K562细胞增殖(p<0.05);药物处理K562细胞24 h,可使胞浆细胞色素C,IκBα含量明显增多,核内NF-κB含量减少.结果提示Na5SeV5O18.3H2O能体外抑制K562细胞增殖,其机理可能与线粒体凋亡和NF-κB/IκBα信号转导有关.     

铀酰离子-细胞色素b_5复合物的分子动力学模拟

铀酰离子(UO_2~(2+))的生物学毒性是由于它能与蛋白质形成稳定的复合物而破坏了蛋白的正常功能。通过使用分子建模和分子动力学(molecular dynamics,MD)模拟,对铀酰离子-细胞色素b_5复合物(UO_2~(2+)-cyt b_5)进行了结构预测。模拟结构显示,UO_2~(2+)通过配位和氢键作用结合到Cyt b_5中谷氨酸Glu37和Glu43,导致Cyt b_5的动力学行为发生轻微改变,而对蛋白整体结构几乎不产生影响。这些现象与Cyt b_5的体内形成以及作为电子传递蛋白的生物功能紧密相联。这些原子水平上理论信息的获得,为铀酰离子的毒性机制,尤其是涉及Cyt b_5的细胞凋亡,提供了深刻内涵。     

纳米火棉胶膜自组装细胞色素c的直接电化学研究

用纳米火棉胶膜将细胞色素c固定在玻碳电极表面,制备了细胞色素c-火棉胶膜修饰电极.吸附在火棉胶膜上的细胞色素c可以与电极发生直接电子传递.在pH=7.0的0.1mol/LPBS缓冲溶液中可得到一对准可逆的细胞色素c的血红素辅基Fe(Ⅲ)/Fe(Ⅱ)电对氧化还原峰,实验求得细胞色素c异相电子传递速率常数k0为65.4μm/s.进一步考察了扫速、溶液pH值等因素对细胞色素c电子传递的影响,并用电化学阻抗法研究了修饰电极的电化学行为.