测定胸腺肽含量几种定量方法的比较

本文用凯氏定氮法、双缩脲法及福林－酚法测定了胸腺肽含量,并加以比较,说明三种方法对其含量测定没有显著差异．在实践中可以根据不同条件选择适当的方法进行实验．     

Immunoproteomic assay of surface proteins of Streptococcus suis serotype 9

Streptococcus suis is an important swine pathogen responsible for a diverse group of diseases. Studies on vaccines have focused on S. suis serotype 2 strains, which are the most invasive isolates worldwide. However, in China S. suis serotype 9 (SS9) is also a prevalent serotype, which is frequently isolated from diseased pigs. Little is known about immunogenic proteins for SS9. Therefore, an immunoproteomic-based approach was developed to identify immunogenic proteins of SS9. Cell wall proteins extracted from SS9 strain GZ0565 isolated from a diseased pig with meningitis were screened by two-dimensional Western blotting using anti-SS9 sera pooled from specific pathogen-free mice. Protein spots were excised from preparative gels and identified by matrix-assisted laser desorption ionization time-of-flight MS (MALDI-TOF-MS) or MALDI-TOF-TOF-MS, which led to the identification of eight immunogenic proteins (arginine deiminase, extracellular solute-binding protein, translation elongation factor Ts, neprilysin, peptide ATP-binding cassette transporter peptide-binding protein, pyruvate kinase, phosphate acetyltransferase, and fructose-bisphosphate aldolase). These immunogenic proteins, which are encoded by genes that are reasonably conserved among SS9 strains, could be developed as vaccine candidates.     

十字花科黑腐病菌中GGDEF结构域蛋白差异的in silico分析

近年来,含有GGDEF结构域(含有甘氨酸(G) (2个),天冬氨酸(D),谷氨酸(E),苯丙氨酸(F)保守氨基酸)的蛋白受到重视,已证实含GGDEF结构域蛋白在细胞信号转导、生长和致病性等方面发挥了重要作用.十字花科黑腐菌8004菌株(Xanthomonas campestris pv.campestris str.8004,Xcc 8004)有32个基因编码含GGDEF结构域蛋白,实验证明其中部分蛋白与Xcc致病性、胞外酶产生、生物膜形成和泳动等生命活动相关.本文利用互联网提供的生物信息学资源,对Xcc 8004不同功能含GGDEF结构域蛋白进行生物信息学分析,着重分析其结构域架构.对蛋白结构域架构整体比较显示,这些蛋白的整体结构域架构具有多样性,共有结构域架构仅有PAS_4-GGDEF-EAL (分布于参与致病的蛋白中);对结构域架构局部比较显示,在参与致病性的含GGDEF结构域蛋白中,PAS_4-GGDEF和GGDEF-EAL为共有结构域架构;在参与内切葡聚糖酶产生的蛋白中,PAS_4-PAS_4、PAS_4-GGDEF和GGDEF-EAL为共有结构域架构.本研究结果将为蛋白质功能预测提供线索.     

Recombinant industrial brewing yeast strains with ADH2 interruption using self-cloning GSH1+CUP1 cassette

A self-cloning module for gene knock-out and knock-in in industrial brewing yeast strain was constructed that contains copper resistance and γ-glutamylcysteine synthetase gene cassette, flanked by alcohol dehydrogenase II gene ( ADH2 ) of Saccharomyces cerevisiae . The module was used to obtain recombined strains RY1 and RY2 by targeting the ADH2 locus of host Y1. RY1 and RY2 were genetically stable. PCR and enzyme activity analysis of RY1 and RY2 cells showed that one copy of ADH2 was deleted by GSH1 + CUP1 insertion, and an additional copy of wild type was still present. The fermentation ability of the recombinants was not changed after genetic modification, and a high level of glutathione (GSH) was secreted, resulting from GSH1 overexpression, which codes for γ-glutamylcysteine synthetase. A pilot-scale brewing test for RY1 and RY2 indicated that acetaldehyde content in fermenting liquor decreased by 21–22%, GSH content increased by 20–22% compared with the host, the antioxidizability of the recombinants was improved, and the sensorial evaluation was also better than that of the host. No heterologous DNA was harbored in the recombinants; therefore, they could be applied in the beer industry in terms of their biosafety.     

Functional epitope of common gamma chain for interleukin-4 binding.

Interleukin 4 (IL-4) can act on target cells through an IL-4 receptor complex consisting of the IL-4 receptor alpha chain and the common gamma chain (gamma(c)). An IL-4 epitope for gamma(c) binding has previously been identified. In this study, the gamma(c) residues involved in IL-4 binding were defined by alanine-scanning mutational analysis. The epitope comprises gamma(c) residues I100, L102, and Y103 on loop EF1 together with L208 on loop FG2 as the major binding determinants. These predominantly hydrophobic determinants interact with the hydrophobic IL-4 epitope composed of residues I11, N15, and Y124. Double-mutant cycle analysis revealed co-operative interaction between gamma(c) and IL-4 side chains. Several gamma(c) residues involved in IL-4 binding have been previously shown to be mutated in X-linked severe combined immunodeficiency. The importance of these binding residues for gamma(c) function is discussed. These results provide a basis for elucidating the molecular recognition mechanism in the IL-4 receptor system and a paradigm for other gamma(c)-dependent cytokine receptor systems.     

Application of matrix solid-phase dispersion methodology to the extraction of endogenous peptides from porcine hypothalamus samples for MS and LC-MS analysis

In this study, we investigated a novel application of matrix solid-phase dispersion (MSPD) methodology for the extraction of endogenous peptides from porcine hypothalamus tissue samples. Several experimental factors of the MSPD procedure were examined. Finally, silica-based octadecyl was chosen as dispersing material and blended with 0.25 g porcine hypothalamus at a ratio of 5, and 10 mL of 60% acetonitrile with 0.2% formic acid in water was chosen as the extraction and elution solvent. This MSPD extraction method was compared to the classic acid extraction method. More peaks were observed in the MSPD extracts (74±5) by MALDI-TOF MS than in acid extracts (34±5). Moreover, 14 potential endogenous peptides were identified in the MSPD extracts after nanoLC-MS/MS analysis, while only 2 endogenous peptides in the acid extracts. These results indicated that MSPD could be employed as a simple and efficient method for the extraction of endogenous peptides from tissues.