Yeast 14-3-3 proteins

14-3-3 proteins form a family of highly conserved proteins which are present in all eukaryotic organisms investigated, often in multiple isoforms, up to 13 in some plants. They interact with more than 200 different, mostly phosphorylated proteins. The molecular consequences of 14-3-3 binding are diverse: this binding may result in stabilization of the active or inactive phosphorylated form of the protein, to a conformational alteration leading to activation or inhibition, to a different subcellular localization, to the interaction with other proteins or to shielding of binding sites. The binding partners, and hence the 14-3-3 proteins, are involved in almost every cellular process and 14-3-3 proteins have been linked to several diseases, such as cancer, Alzheimer's disease, the neurological Miller-Dieker and spinocerebellar ataxia type 1 diseases and bovine spongiform encephalopathy (BSE). The yeasts Saccharomyces cerevisiae and Schizosaccharomyces pombe both have two genes encoding 14-3-3 proteins, BMH1 and BMH2 and rad24 and rad25, respectively. In these yeasts, 14-3-3 proteins are essential in most laboratory strains. As in higher eukaryotes, yeast 14-3-3 proteins bind to numerous proteins involved in a variety of cellular processes. Recent genome-wide studies on yeast strains with impaired 14-3-3 function support the participation of 14-3-3 proteins in numerous yeast cellular processes. Given the high evolutionary conservation of the 14-3-3 proteins, the experimental accessibility and relative simplicity of yeasts make them excellent model organisms for elucidating the function of the 14-3-3 protein family.     

3-苄硫基噻吩、3-糠硫基噻吩和3-十二烷硫基噻吩的合成及其香气特征

-40℃下,3-溴噻吩先与n-丁基锂反应,再依次加入碘、活性镁粉和二硫醚,在室温下分别反应4、4.5、4.5h,分别合成3-苄硫基噻吩、3-糠硫基噻吩和3-十二烷硫基噻吩,收率分别为51.1%、29.0%和27.4%.这些化合物结构都通过IR、MS和~1HNMR测试技术进行了表征,并对其进行了初步香味评价.结果表明,它们都具有基本肉香味特征,阈值为19.78～30.11mg·kg~(-1),留香时间可达2.5～3.5h.     

英国农业渔业食品部对酱油和同类产品中3-氯-1.2-丙二醇的检测

欧洲共同体食品安全与标准组织(ＪＦＳＳＧ)的出版物于1999年8月31日通报了在英国买到的酱油及同类产品中3—ＭＣＰＤ的测定结果。1999年8、9月从零售商买到大豆酱油、蘑菇酱油、蚝油及其它酱油40个样品,用检验限度为001ｍｇ/ｋｇ的法定方法测定。测定值与食品顾问委员会(ＦＡＣ’Ｓ)的推荐值进行比较,下面的报告表明一些牌子的酱油含3—ＭＣＰＤ的含量比较高。(在其它欧洲国家采样)。1　样品的检测表1　酱油与相关产品中3—ＭＣＰＤ测定值1999年3—ＭＣＰＤｍｇ/ｋｇ样　品　数　目总样品数酱油其它产品未检出21165001～010ｍｇ/ｋｇ523010…     

醇脱氢酶不对称还原2-[3-[3-[2-(7-氯-2-喹啉基)乙烯基]苯基]-3-羟基丙基]苯甲酸甲酯

孟鲁司特钠是主要的抗哮喘药物之一,2-[3-(S)-[3-[2-(7-氯-2-喹啉基)乙烯基]苯基]-3-羟基丙基]苯甲酸甲酯是孟鲁斯特钠的关键手性砌块.以实验室筛选到的醇脱氢酶不对称还原2-[3-[3-[2-(7-氯-2-喹啉基)乙烯基]苯基-3-羟基丙基]苯甲酸甲酯,制备2-[3-(S)-[3-[2-(7-氯-2-喹啉基)乙烯基]苯基-3-羟基丙基]苯甲酸甲酯.在辅酶添加量为0.1 g/L,底物浓度为219.3 mmol/L,菌体用量为30 g/L,pH 7.5,45 ℃反应7h后,底物转化率达到100％,时空产率为31.2 mmol/(L·h),产物e.e.值大于99.9％.通过分批补料,反应5h,底物转化率达到100％,e.e.＞99.9％,时空产率达43.7 mmol/(L,h),是一次性投料的1.4倍.     

响应面法优化3-甲氧基-4-羟基苯乙醇酸的合成

以愈创木酚和乙醛酸为原料,碱性条件下缩合反应生成3 -甲氧基-4-羟基苯乙醇酸(MH-PA),探讨物料比、溶液pH值、反应温度及反应时间4个单因素对MHPA得率的影响,并在单因素试验的基础上利用Box - Benhnken中心组合试验和响应面分析法得出MHPA合成的最佳工艺条件为:愈创木酚∶乙醛酸=1.7∶1,溶液pH值12,反应温度53℃,反应时间5.14h,此条件下MHPA合成的产率可达82.56％.以4A分子筛和沸石做催化剂,MHPA收率可分别提高到85.63％和86.18％.     

The Candida albicans 14-3-3 gene, BMH1, is essential for growth.

The 14-3-3 proteins are a family of conserved small acidic proteins that have been implicated in playing major roles in a wide variety of signalling cascades. In Saccharomyces cerevisiae, the 14-3-3 genes (BMH1 and BMH2) are essential for normal pseudohyphal induction and normal bud cell development. The Bmh proteins function in the cAMP-dependent RAS/MAPK and rapamycin-sensitive signalling cascades. Deletion of only one BMH gene demonstrates no phenotypic differences under normal growth conditions. Strains deleted of both BMH1 and BMH2 are either non-viable or demonstrate sensitivity to environmental stresses. In Schizosaccharomyces pombe, the BMH homologues (RAD24 and RAD25) are essential for cell cycle control after DNA damage and deletion of both genes renders the cell inviable. The 14-3-3 gene in Candida albicans (BMH1) was identified using a novel adherence assay and differential display RT-PCR. Unlike other yeasts, C. albicans has only one 14-3-3 gene (BMH1). It was not possible to construct double knockouts by routine methods. These results suggested that the C. albicans BMH1 gene is essential. The essentiality of C. albicans BMH1 was confirmed by a PCR disruption technique. The C. albicans bmh1 Delta/BMH1 heterozygotes exhibit growth and morphogenetic defects. Therefore, the BMH1 gene in C. albicans (Accession No. AF038154) is an excellent candidate to improve our understanding of the coordinate regulation of cell cycle and morphogenesis.     

破壁方法对红球菌11-3胞内几丁质脱乙酰酶释放的影响

红球菌11-3是一株高产几丁质脱乙酰酶(CDA)的菌株，几丁质在该酶的催化作用下可转化为壳聚糖，该酶在壳聚糖的生产中具有重要作用。红球菌11-3菌株所产CDA为胞内酶，成为催化反应的一大障碍。为了提高CDA的释放率，本研究首先利用不同的物理方法(反复冻融、超声、球磨、匀浆和液氮研磨)、化学方法(表面活性剂处理、氯仿处理)和生物学方法(溶菌酶处理)对红球菌11-3进行破壁处理，测定CDA酶活力和释放率，并通过扫描电子显微镜观察细胞形态变化。结果表明，不同方法的破壁效果存在很大差异，其中，液氮研磨法破壁效果最佳，菌体表面出现细密的孔洞，CDA释放率为45.13%，总酶活力损失率为2.03%；匀浆处理法次之，CDA释放率为16.00%，总酶活力损失率为9.18%。利用匀浆和液氮研磨联合处理红球菌11-3细胞，细胞表面产生更多、更大的孔洞，CDA释放率高达86.17%，总酶活力损失率为9.11%，上清液中CDA酶活力为480.2 U/mL，较液氮研磨法相比提高了1.48倍。结论:匀浆和液氮研磨联合处理可有效破坏红球菌11-3细胞壁，提高胞内CDA释放效率。本研究结果对红球菌11-3内CDA应用于壳聚糖的生产具有参考作用。     

关于Diophantine方程x~3-5~3=3py~2

设p是给定的素数,运用初等数论方法证明了方程x3-53=3py2有适合gcd(x,y)=1的正整数解(x,y)的充要条件是p=Q(27a4+45a2+25),其中a是正整数,Q(27a4+45a2+25)是27a4+45a2+25的无平方因子部分.由此可知,当p≠7或13(mod30)时,该方程没有适合gcd(x,y)=1的正整数解(x,y).     

饮用水中亚氯酸根离子和氯酸根离子的检测

本文用离子色谱法检测了饮用水的亚氯酸根离子和氯酸根离子, 在水样中添加EDA保存剂能准确检测ClO2-浓度,同时不影响ClO3- 的分析结果.