乙醇对鲍鱼碱性磷酸酶活力与构象的影响

以乙醇为效应物研究对鲍鱼碱性磷酸酶(ALP)活力影响的结果表明．酶的剩余活力随着乙醇浓度增大而迅速下降，乙醇浓度40％可使酶活力完全丧失．说明乙醇对鲍鱼ALP有明显的失活作用，JG50为13％．含较低浓度乙醇(30％)的失活过程是可逆的反应．测定乙醇对酶的失活作用机理．结果表明乙醇对鲍鱼ALP的失活作用是非竞争性机制，说明底物存在不影响乙醇对酶的失活作用．应用荧光光谱、紫外吸收光谱研究鲍鱼ALP经乙醇微扰后的分子构象变化，发现乙醇对酶分子构象有显的影响，酶的内源荧光强度随乙醇浓度增大而增强．荧光发射峰逐渐发生红移．紫外吸收光谱在276nm吸收峰随乙醇浓度增大而增强．这些结果表明．酶蛋白分子中的生色基团残基的微环境发生变化．     

厦门西港沉积物中有机氯化合物对碱性磷酸酶活力的影响分析

厦门西港沉积物中碱性磷酸酶活力水平的研究已表明,ＡＬＰａｓｅ在沉积物磷转化过程中起了一定的作用。为进一步研究沉积物中有机氯化合物对ＡＬＰａｓｅ活力的影响,对厦门西港沉积物中ＡＬＰａｓｅ活力和ＨＣＨｓ、ＤＤＴｓ、ＰＣＢｓ的含量进行了同步检测,结果表明厦门西港沉积物除了个别站位有机氯化合物含量较高外,整体上有机氯化合物的污染并不明显,梗因而对ＡＬＰａｓｅ的影响也较低,但在有机氯化合物污染较重的站位,其     

Protein phosphatases and their potential implications in neuroprotective processes

Several neurological disorders such as stroke, amyotrophic lateral sclerosis and epilepsy result from excitotoxic events and are accompanied by neuronal cell death. These processes engage multiple signalling pathways and recruit numerous molecular components, in particular several families of protein kinases and protein phosphatases. While many investigations have examined the importance of protein kinases in excitotoxicity, protein phosphatases have not been well studied in this context. However, recent advances in understanding the functions of protein phosphatases have suggested that they may play a neuroprotective role. In this review, we summarize some of the recent findings that illustrate the pleiotropic and complex functions of tyrosine and serine/threonine protein phosphatases in the cascade of events leading to neuronal cell death, and highlight their potential intervention in limiting the extent of neuronal death.Received 8 January 2005; received after revision 3 March 2005; accepted 14 March 2005     

Calcification of Pericardium Treated with Different Phospholipids *

ＩｎｔｒｏｄｕｃｔｉｏｎＯｎｅｏｆｔｈｅｍａｊｏｒｆａｃｔｏｒｓｉｎｔｈｅｆａｉｌｕｒｅｏｆｐｏｒｃｉｎｅｂｉｏｌｏｇｉｃａｌｐｒｏｓｔｈｅｓｅｓａｎｄｔｈｏｓｅｍａｄｅｏｆｂｏｖｉｎｅｐｅｒｉｃａｒｄｉｕｍ（ＢＰ）ｉｓｔｉｓｓｕｅｃａｌｃｉｆｉｃａ...     

Partial purification and characterization of acid phosphatase from sporulated oocysts ofEimeria tenella

Summary Acid phosphatase ofEimeria tenella oocysts (Peak II) was purified 77-fold with a recovery of 26% using protamine sulfate precipitation, DEAE-cellulose chromatography and Sephadex G-200 gel filtration. This enzyme occurs in multiple forms as indicated by two peaks which can be separated by DEAE-cellulose chromatography and polyacrylamide gel electrophoresis. The partially purified enzyme has optimal activity at pH 4.5. With p-nitrophenyl phosphate the Km and V_max values for (Peak II) were 25 mM and 1.57 mol/min/mg protein, respectively. The enzyme (Peak II) ist strongly inhibited by Hg⁺⁺, Cu⁺⁺, iodoacetamide, fluoride and molybdate. Tartrate and other divalent metal ions have no effect on enzyme activity. The partially purified Peak II phosphatase is not a glycoprotein as it is not absorbed on concanavalin-A Sepharose and its treatment with bacterial neuraminidase does not alter its elution profile through DEAE cellulose.     

牙齿矿化的低磷酸酯酶血症成因及对策

低磷酸酯酶血症是罕见的遗传性疾病,其典型特征有骨、牙齿矿化异常及血清、骨内碱性磷酸酯酶活性缺乏,临床表现多样.研究其分子发病机理、临床表现及治疗的最新进展,建议口腔医师接诊牙齿异常脱落患者应考虑其早期病史并做针对性诊断和治疗.     

氨氮胁迫对拟穴青蟹腺苷三磷酸酶和磷酸酶比活力的影响

采用实验生态学的方法研究了海水中分别添加氨氮(以NH4Cl作为氨氮源)0(C0组,对照组)、10(C10组)、20(C20组)、30(C30组)、40 mg/L(C40组),胁迫24,48,72,96 h对拟穴青蟹(Scylla paramamosain)组织器官中腺苷三磷酸酶(ATPase)和磷酸酶比活力的影响.结果表明,拟穴青蟹鳃Na+-K+-ATPase比活力,C10组、C20组在胁迫24 h时随氨氮浓度升高而增大,胁迫48,72和96 h时则随氨氮浓度升高而下降(p<0.05),C30组、C40组则随胁迫时间延长一直下降;而C40组拟穴青蟹鳃Ca2+-Mg2+-ATPase比活力却随胁迫时间延长而升高.氨氮胁迫48,72和96 h,拟穴青蟹鳃和肝胰腺酸性磷酸酶(ACP)比活力显著下降(p<0.05);肌肉ACP比活力则随氨氮浓度升高和胁迫时间延长而显著下降(p<0.05);鳃和肝胰腺碱性磷酸酶(AKP)比活力随着氨氮浓度升高而下降(p<0.05);肌肉AKP比活力在氨氮胁迫24 h时随氨氮浓度升高而升高(p<0.05).可见,氨氮胁迫显著影响拟穴青蟹生理效应.     

草鱼碱性磷酸酶的分离纯化与部分性质研究

用Tris—HCl缓冲液抽提，硫酸铵分级沉淀，DEAE-纤维素和葡聚糖凝胶层析，从草鱼肠中提取出碱性磷酸酶（ALP）．提取倍数为6．74，比活为684U／mg蛋白．酶液经PAGE呈现单一带，该酶催化对硝基苯磷酸二钠（pNPP）水解反应的最适pH值为10．41，最适温度为27℃，Km值为1．01mmol／L，酶的热稳定性与pH稳定性研究表明：该酶在pH6．6～11．5区间和在温度低于45℃下稳定．研究金属离子对酶活力影响的结果表明：一价金属离子Li^＋、Na^＋和K^＋对酶活力没有影响；二价金属离子Mg^2＋、Mn^2＋和Co^2＋对酶有不同程度的激活作用；Zn^2＋对酶有抑制作用．     

Spatial Memory Deficit and Tau Hyperphosphorylation Induced by Inhibiting PP2A in Rat Brain

Hyperphosphorylation of Tau in Alzheimer＇s disease （AD） brain appears to be caused by a down-regulation of protein phospbatase 2A （PP2A）. In this study, we selectively inhibited PP2A by injection of okadaic acid （OA） into the Meynert nucleus basalis of rats and found that 0.4 pmol of OA injeetion induced approximately 60% inhibition of PP2A 24 h after injection, 13% inhibition 48 h after injection and no obvious inhibition 72 h after injection. Hyperphosphorylation of Tau at Ser-198/ Ser-199/Ser-202 and Ser-396/Ser-404 and spatial memory deficit of rats were induced 24 h after 0. d prnol of OA injection. This study suggests that a dowreregulation of PP2A may underlie almormal hyperphosphorylation of cytoskeletal proteins leading to neurofibrillary degeneration in AD.     

黑人妇女的创造性与自我解放——解读艾丽丝·沃克《紫色》中黑人女性的生存之道

艾丽丝·沃克是当代美国文坛黑人女作家的代表。她在其长篇小说《紫色》中着力描绘了黑人女性的内心世界和她们所拥有的创造性。揭露了黑人妇女的艰难处境和她们抗争的曲折历程。这一历程也充分体现了作者对黑人妇女的理解和对其解放之路的探究。《紫色》中以塞莉为代表的一群黑人姐妹，通过写作、反抗、缝纫、歌唱、旅行等方式，寻找自我解放，尽情挥洒其创造天性，最终摆脱枷锁，成为有尊严有个性的自由女性。