苏云金芽胞杆菌产苏云金素菌株CT-43及其 缺失突变株的差异蛋白

[目的]苏云金素(Thuringiensin)的合成和代谢途径的相关研究在国内外一直进展缓慢,本文拟从蛋白质组水平揭示与苏云金素合成或代谢相关的蛋白.[方法]利用双向电泳技术研究了高产苏云金素的苏云金芽胞杆菌野生菌株CT-43、其高产突变菌株CT-43-1C及不产突变菌株BMB0806在蛋白表达水平的差异,然后对差异蛋白点进行质谱鉴定,最后对鉴定出的蛋白进行生物信息学分析.[结果]与野生型和高产菌株相比,在BMB0806中发现了13个差异显著的蛋白点,鉴定出了其中的9个,生物信息学结果显示有6个蛋白可能与苏云金素合成或代谢相关.[结论]通过蛋白质组研究找到了6个可能与苏云金素合成或代谢相关的蛋白,为苏云金素合成基因簇的克隆和合成途径的验证提供了有力的证据.     

Applications of dual-color fluorescence cross-correlation spectroscopy in antibody binding studies

Two-photon dual-color fluorescence cross-correlation spectroscopy (DC-FCCS) was applied to study the binding interactions of monoclonal antibodies (mAbs) and protein antigens. We measured the binding constant of the interaction of a 32-amino acid brain natriuretic peptide (BNP) with a mAbs and demonstrated the utility of DC-FCCS in studies of antibody sandwiches, trimolecular formations, where two different antibodies bind the same antigen simultaneously. We also show the use of DC-FCCS for monitoring competitive displacement of the labeled antibody in antibody-antigen complexes and subsequent determination of the pertinent dissociation rate (off-rate). The off-rate measurements were performed for two mAbs toward tissue inhibitor 1 of metalloproteinases (TIMP-1). From a methodological perspective, selection of the best labeling protocols and careful optimization of the FCCS instrumentation are essential to achieve the highest cross-correlation signal. When working in vitro, it is practical to generate a complete binding curve using the normalized cross-correlation signal and then fit the experimental points to a binding model. DC-FCCS offers the sensitivity and all other advantages of a solution phase fluorescence-based technique. For systems containing proteins of a similar size that interact without substantial changes in the fluorescence intensity, DC-FCCS serves as a preferred means of measuring solution phase binding constants.     

The Release of Extrinsic Polypeptides and Manganese Cluster from Photosystem 2 Membranes under High Hydrostatic Pressure

Three extrinsic polypeptides and manganese cluster were sequentially released from the membrane when photosystem 2 (PS2) membranes were kept under high hydrostatic pressure. The 17 kDa polypeptide was the most sensitive, while the 33 kDa polypeptide was the most reluctant to the treatment with high pressure. The release of manganese was not simply correlated with the loss of 33 kDa polypeptide. The losing of oxygen-evolving activity of PS2 was synchronised with the releasing of extrinsic polypeptides and manganese.     

5—氟尿苷的微生物转化

5 氟尿苷 (简称ＦＵＲ)是抗肿瘤核苷药物脱氧氟尿苷 (Ｆｌｏｘｕｒｉｄｉｎｅ ,简称ＤＦＵＲ)的合成中间体。脱氧氟尿苷是一种抗代谢类抗肿瘤药 ,在体内可以部分转化为氟尿嘧啶 (简称ＦＵ) ,二者具有相似的作用途径和抗肿瘤谱。与ＦＵ相比 ,由于ＤＦＵＲ的抗肿瘤活性高且毒副反应小 ,主要用于治疗晚期结直肠癌和各种类型肝癌。在国内 ,采用化学法合成的ＤＦＵＲ业已进入临床研究阶段[1]采用化学合成法生产ＤＦＵＲ时 ,由于反应过程中需将碱基或核糖残基的部分基团进行保护 ,而且产物为多种核苷异构体和其它副产品的混合物 ,需要进一步分离 ,…     

Inhibition of serine proteases by functionalized sulfonamides coupled to the 1,2,5-thiadiazolidin-3-one 1,1 dioxide scaffold.

A challenge associated with drug design is the development of selective inhibitors of proteases (serine or cysteine) that exhibit the same primary substrate specificity, that is, show a preference for the same P(1) residue. While these proteases have similar active sites, nevertheless there are subtle differences in their S and S' subsites which can be exploited. We describe herein for the first time the use of functionalized sulfonamides as a design and diversity element which, when coupled to the 1,2,5-thiadiazolidin-3-one 1,1 dioxide scaffold yields potent, time-dependent inhibitors of the serine proteases human leukocyte elastase (HLE), proteinase 3 (PR 3) and cathepsin G(Cat G). Our preliminary findings suggest that (a) appending to the 1,2,5-thiadiazolidin-3-one 1,1 dioxide scaffold recognition and diversity elements that interact with both the S and S' subsites of a target protease may result in optimal enzyme selectivity and potency and, (b) functionalized sulfonamides constitute a powerful design and diversity element with low intrinsic chemical reactivity and potentially wide applicability.     

水杨酸调控盐胁迫下羽衣甘蓝种子萌发的机理

盐胁迫是植物种子萌发与植株生长的重要限制因子。以羽衣甘蓝(Brassica oleracea var.acephala)名古屋为材料,研究不同盐分对其种子萌发的影响,探索水杨酸(SA)及其合成抑制剂氨基茚磷酸(AIP)处理对羽衣甘蓝种子萌发的调控效应。实验结果表明,150与200 mmol·L^–1 NaCl处理后的羽衣甘蓝种子活力显著降低。盐胁迫显著降低种子的吸水速率、种子活力与幼苗质量,降低苯丙氨酸裂解酶活性与内源SA含量,提高过氧化氢(H2O2)与超氧阴离子(O2^–.)含量。SA可以缓解盐胁迫对羽衣甘蓝种子活力的抑制作用,通过促进内源SA合成,从而提高种子吸水率与种子活力,促进种子对K^+、Mg^2+的吸收,降低Na+含量。此外,外源施加SA能够显著增强超氧化物歧化酶和过氧化物酶活性,降低H2O2与O2^–.的积累。相反,氨基茚磷酸(AIP)处理能够增强盐胁迫对种子萌发的抑制作用,推测这与AIP处理能够显著降低种子内源SA含量密切相关。研究表明外源SA主要通过提高保护酶活性、降低活性氧积累和维持体内离子平衡来增强羽衣甘蓝的耐盐性。     

Correction to: Protective Effects of 28-O-Cafeoyl Betulin (B-CA) on the Cerebral Cortex of Ischemic Rats Revealed by a NMR-Based Metabolomics Analysis

Neurochemical Research - In the original version of this article, unfortunately the Fig. 3C and 3F were published with incorrect version. The correct version of the Fig. 3C and 3F...     

HDAC1 Regulates the Proliferation of Radial Glial Cells in the Developing Xenopus Tectum

In the developing central nervous system (CNS), progenitor cells differentiate into progeny to form functional neural circuits. Radial glial cells (RGs) are a transient progenitor cell type that is present during neurogenesis. It is thought that a combination of neural trophic factors, neurotransmitters and electrical activity regulates the proliferation and differentiation of RGs. However, it is less clear how epigenetic modulation changes RG proliferation. We sought to explore the effect of histone deacetylase (HDAC) activity on the proliferation of RGs in the visual optic tectum of Xenopus laevis. We found that the number of BrdU-labeled precursor cells along the ventricular layer of the tectum decrease developmentally from stage 46 to stage 49. The co-labeling of BrdU-positive cells with brain lipid-binding protein (BLBP), a radial glia marker, showed that the majority of BrdU-labeled cells along the tectal midline are RGs. BLBP-positive cells are also developmentally decreased with the maturation of the brain. Furthermore, HDAC1 expression is developmentally down-regulated in tectal cells, especially in the ventricular layer of the tectum. Pharmacological blockade of HDACs using Trichostatin A (TSA) or Valproic acid (VPA) decreased the number of BrdU-positive, BLBP-positive and co-labeling cells. Specific knockdown of HDAC1 by a morpholino (HDAC1-MO) decreased the number of BrdU- and BLBP-labeled cells and increased the acetylation level of histone H4 at lysine 12 (H4K12). The visual deprivation-induced increase in BrdU- and BLBP-positive cells was blocked by HDAC1 knockdown at stage 49 tadpoles. These data demonstrate that HDAC1 regulates radial glia cell proliferation in the developing optical tectum of Xenopus laevis.