改性处理对豌豆蛋白结构和功能特性的影响

以豌豆蛋白为原料,研究了挤压处理、磷酸化处理、挤压协同磷酸化处理三种改性处理方法对豌豆蛋白二硫键含量、二级结构含量、亚基组成,以及表面疏水性、溶解性、持水性及持油性、乳化活性及乳化稳定性的影响。结果表明,不同改性处理条件下豌豆蛋白结构及功能特性均发生变化,与挤压处理和磷酸化处理相比,挤压协同磷酸化处理对豌豆蛋白理化性质影响最为明显。与未改性豌豆蛋白相比,挤压协同磷酸化处理的豌豆蛋白二硫键含量增加了26.25%;二级结构中β-折叠含量增加了15.06%,β-转角含量减少了9.85%;亚基组成中豆球蛋白A和豆球蛋白B含量减少;表面疏水性提高了101.95%。挤压协同磷酸化处理后的豌豆蛋白溶解性、持油性、乳化活性及乳化稳定性显著高于未改性豌豆蛋白(P<0.05),而单一的挤压处理、磷酸化处理对豌豆蛋白这些功能性的改善效果不如挤压协同磷酸化处理,特别是挤压处理后豌豆蛋白溶解性减小。     

蛋白质磷酸化修饰研究进展

 蛋白质磷酸化是由蛋白质激酶催化的磷酸基转移反应,是最常见、最重要的蛋白质翻译后修饰方式之一,是一种普遍的生命活动调节方式,在细胞信号转导过程中起重要作用。本文介绍了蛋白质磷酸化修饰的主要类型与功能、磷酸化蛋白的鉴定及磷酸化位点的预测等方面研究进展,并着重介绍了一些灵敏度高、特异性强的以同位素标记、免疫印迹-化学发光法等作为核心的磷酸化蛋白质分析方案。Western blot方法被证明是鉴别磷蛋白的灵敏、特异方法,而NanoPro100/1000超微量蛋白分析系统等又在此基础上加以改善。蛋白磷酸化分析工具和软件的发展也很迅猛。     

p53修饰及其相互作用的研究进展

p53是一个重要的抑癌分子, 在抑制肿瘤发生发展过程中起关键作用. 正常生理状况下, p53水平很低, 细胞受到外界刺激后, p53水平升高, 稳定性增强, 继而参与细胞周期阻滞、细胞衰老、DNA修复或细胞凋亡等重要的生命过程. p53功能的精确调控至关重要, 涉及一系列翻译后修饰(泛素化、乙酰化、磷酸化、甲基化、泛素样蛋白质修饰等等), 这些作用互相协作、相互影响, 从而精密调节p53的活性. 本文探讨p53的各种修饰作用, 并分析其各种修饰与肿瘤发生的相互关系, 为肿瘤的治疗提供一些参考价值.     

组胺能与y-氨基丁酸能神经传递在问位核神经元信息加工中的作用

小脑间位核（interpositusnucleus,IN）主要接受1一氨基丁酸（GABA）能纤维支配,同时接受组胺能纤维的调节．本研究在小脑脑片上研究了GABA和组胺对单个IN神经元电活动的共同作用．持续灌流组胺或同时施加组胺和GABA,81．2％（69／85）神经元,GABA及其激动剂的效应都被组胺削弱（持续灌流n=33;同时施加n=36）．这种削弱效应能够被纽胺H,受体阻断剂ranitidine（n=10）和PK。抑制剂H一89阻断（n=8）,fors—kolin模拟组胺的效应（n=9）．结果表明组胺和GABA对IN神经元的电活动具有交互调节作用：通过激活H：受体偶联的G—protein—AC—PK。信号通路,磷酸化GABAB和GABA^受体,降低受体功能．推测受体间的对话的工作模式,可能是整个大脑神经元活动的某些药理作用和生理活动调节的基础;如果对话紊乱,可能导致大脑功能障碍．     

丙硫基磷酰化合物的研究(Ⅱ)——S-丙基-O、O-二芳基硫赶磷酸酯的合成

通过S-丙基硫赶磷酰二氯酯与相应的酚类进行磷酰化反应合成了六种S-丙基-O、O-二芳基磷酸酯,并对它们的合成、IR和MS进行了初步的讨论。     

Regulation of muscle creatine kinase by phosphorylation in normal and diabetic hearts

Protein kinase C (PKC) is an important signaling molecule in the heart, but its targets remain unclear. Using a PKC substrate antibody, we detected a 40-kDa phosphorylated cardiac protein that was subsequently identified by tandem mass spectroscopy as muscle creatine kinase (M-CK) with phosphorylation at serine 128. The forward reaction using ATP to generate phosphocreatine was reduced, while the reverse reaction using phosphocreatine to generate ATP was increased following dephosphorylation of immunoprecipitated M-CK with protein phosphatase 2A (PP2A) or PP2C. Despite higher PKC levels in diabetic hearts, decreased phosphorylation of M-CK was more prominent than the reduction in its expression. Changes in CK activity in diabetic hearts were similar to those found following dephosphorylation of M-CK from control hearts. The decrease in phosphorylation may act as a compensatory mechanism to maintain CK activity at an appropriate level for cytosolic ATP regeneration in the diabetic heart. Received 15 September 2008; received after revision 30 September 2008; accepted 13 October 2008     

Regulation of mitochondrial aconitase by phosphorylation in diabetic rat heart

Mitochondrial dysfunction and protein kinase C (PKC) activation are consistently found in diabetic cardiomyopathy but their relationship remains unclear. This study identified mitochondrial aconitase as a downstream target of PKC activation using immunoblotting and mass spectrometry, and then characterized phosphorylation-induced changes in its activity in hearts from type 1 diabetic rats. PKCβ₂ co-immunoprecipitated with phosphorylated aconitase from mitochondria isolated from diabetic hearts. Augmented phosphorylation of mitochondrial aconitase in diabetic hearts was found to be associated with an increase in its reverse activity (isocitrate to aconitate), while the rate of the forward activity was unchanged. Similar results were obtained on phosphorylation of mitochondrial aconitase by PKCβ₂ in vitro. These results demonstrate the regulation of mitochondrial aconitase activity by PKC-dependent phosphorylation. This may influence the activity of the tricarboxylic acid cycle, and contribute to impaired mitochondrial function and energy metabolism in diabetic hearts. Received 31 October 2008; received after revision 17 December 2008; accepted 2 January 2009     

从L-丝氨酸合成新型旋光活性环状磷脂的替加氟(Tegafur)和尿苷缀合物

从Ｌ－丝氨酸出发,经酯化、环磷酰化、磷酰化、加硫等步骤得到替加氟、尿苷硫代环磷酰胺酯缀合物２、３．Ｌ－丝氨酸酯经Ｎ－烷基化,然后再与磷酰二氯关环,进一步与替加氟乙醇反应得到环磷脂缀合物４．考察了两种环磷酰化反应中碳手性中心对磷原子的不对称诱导效果,并用硅胶柱层析分离了产物２、３、４ 的非对映异构体．基于ＮＭＲ数据,对它们的构型进行了讨论和初步的确定,它们的抗癌活性正在测试当中．     

Causes of oxidative stress in Alzheimer disease

Oxidative stress is one of the earliest events of Alzheimer disease (AD), with implications as an important mediator in the onset, progression and pathogenesis of the disease. The generation of reactive oxygen species (ROS) and its consequent cellular damage/response contributes to much of the hallmark AD pathology seen in susceptible neurons. The sources of ROS-mediated damage appear to be multi-faceted in AD, with interactions between abnormal mitochondria, redox transition metals, and other factors. In this review, we provide an overview of these potential causes of oxidative stress in AD.     

TTDN1 is a Plk1-interacting protein involved in maintenance of cell cycle integrity

Polo-like kinase 1 (Plk1) is a highly conserved serine/threonine kinase that plays critical roles in many cell cycle events, especially in mitosis. In the present study, we identified TTDN1 as a potential interacting partner of Plk1 in yeast two-hybrid screens. Sequence analysis indicates that TTDN1 contains a consensus Plk1-binding motif at its C terminus. TTDN1 colocalizes with Plk1 at the centrosome in mitosis and the midbody during cytokinesis. TTDN1 is phosphorylated by Cdk1 in mitosis, and this is required for its interaction with Plk1. Site-directed mutagenesis indicates that TTDN1 is phosphorylated at multiple residues, including Ser93 and Ser104. Mutation of Thr120 of TTDN1 abolishes its interaction with Plk1, suggesting phosphorylation of Thr120 in the consensus Plk1-binding motif is required for its interaction with Plk1. Overexpression of TTDN1 or its knockdown by siRNA causes multi-polar spindles and multiple nuclei, suggesting that TTDN1 plays a role in regulating mitosis and cytokinesis. Received 27 November 2006; received after revision 4 January 2007; accepted 25 January 2007 Y. Zhang, Y. Tian: These authors contribute equally to this work.