肇庆星湖湿地可培养放线菌多样性

摘要:【目的】探究星湖湿地可培养放线菌物种多样性,筛选潜在药源活性代谢产物产生菌,为后续菌种资源开发奠定基础。【方法】采用5种选择性分离培养基分离星湖湿地底泥中的放线菌,通过16S rRNA基因同源性分析代表性菌株的物种多样性;以3株病原细菌为指示菌检测分离菌株的抑菌活性;PCR扩增代表菌株的聚酮合酶(PKS I、PKS II)基因、非核糖体多肽合成酶(NRPS)基因、安莎类化合物(AHBA)基因及3-羟基-3-甲基戊二酰辅酶A还原酶(HMGA)基因。【结果】分离到135株放线菌菌株,被鉴定为放线菌纲的7 个目、10个科、13个属,优势类群为链霉菌、小单孢菌及诺卡氏菌。83株检测菌中,24.09%抗金黄色葡萄球菌(Staphylococcus aureus),4.8%抗大肠杆菌(Escherichia coli);24株高活性菌株中PKS I阳性率16.7%,PKS II阳性率62.5%,NRPS阳性率16.7%,AHBA阳性率12.5%,HMGA阳性率29.2%。活性复筛及HPLC结果显示,菌株XD007、XD114和XD128显著抑制3株病原指示菌,且能产生大量次级代谢产物。【结论】星湖湿地底泥中放线菌资源丰富,筛选到的活性菌株可用于后续药源活性次级代谢产物的分离。     

全耐药鲍曼不动杆菌分子分型和分子流行病学调查

重复片段引物PCR和随机扩增多态性DNA(RAPD)技术对临床分离全耐药不动杆菌分子分型,并进行流行病学调查.从ICU病房感染多重耐药不动杆菌患者的标本分离不动杆菌,碱裂解法提取全基因组,重复片段引物PCR(Rep-PCR)和随机引物扩增(RAPD),对8株临床分离的全耐药菌基因分型,并与生物学分型和质粒分型比较,调查医院流行全耐药菌的基因型.结果显示,8株分离菌经两对重复片段引物分型可分为6种和4种基因型,经随机引物分型为4种和3种基因型,经质粒分型可分为2种基因型,生物学分型归属为1种表型.PCR方法用于全耐药不动杆菌分子分型简便易行,重复性好,适合医院感染流行病学调查,本医院同一部门出现多种基因型,各科室间不存在交叉传染.     

快速鉴定诺卡菌的多重聚合酶链反应的建立

为快速准确鉴定诺卡菌,首先设计针对诺卡菌rpoB、secA1、16S rRNA基因的引物,利用单重聚合酶链反应(PCR)和测序验证引物的特异度,建立多重PCR鉴定系统,在同一反应体系和条件下对44株诺卡菌标准株、44株临床分离株和7株对照株进行扩增。结果显示,利用单对引物对其中2株诺卡菌(标准株DSM43003、临床株CDC 51)进行扩增,出现的条带均为与目的片段长度一致的单一条带,经测序并经基本局部比对搜索工具(BLAST)验证扩增片段为目的基因。建立的多重PCR结果显示,44株诺卡菌标准株中有43株(97.7%)、44株临床分离株中有42株(95.5%)rpoB、secA1、16S rRNA这3条片段均显示,7株对照株均未显示条带。结果提示,本研究建立的多重PCR简单、快速、灵敏度高、特异度好,适用于诺卡菌的快速鉴定。     

肺炎克雷伯菌产碳青霉烯酶特性与耐药趋势研究

目的探讨临床分离的耐碳青霉烯类肺炎克雷伯菌(Klebsiella pneumoniae carbapenem-resistant,CRKP)的耐药机制及耐药趋势,为抗感染治疗提供依据。方法收集2008-2013年分离的CRKP 178株,分别运用VITEK-2 Compact全自动细菌分析仪和K-B纸片法检测菌株对药物的敏感性,改良Hodge试验确定是否产碳青霉烯酶以及EDTA抑制试验确定是否产金属酶,用PCR扩增和基因测序技术检测耐药基因。结果临床分离出肺炎克雷伯菌(Klebsiella pneumonia,Kpn)中CRKP的比例从2008年0.1%升至2013年2.2%,呈明显上升趋势;药敏结果显示,其对碳青霉烯类高度耐药外,对头孢曲松、氨曲南、环丙沙星等多种抗菌药物呈现出多重耐药;改良Hodge试验阳性170株(阳性率为95.5%);EDTA双纸片协同试验阳性1株(阳性率为0.6%)。PCR共检出150株携带KPC-2酶基因(blaKPC-2),阳性率为84.3%(150/178),1株肺炎克雷伯菌同时携带blaKPC-2和blaIMP-4,占0.6%(1/178)。结论台州医院分离的CRKP比例逐年升高,对多种抗菌药物高度耐药,产KPC-2型碳青霉烯酶是分离菌株对碳青霉烯类抗菌药物耐药主要原因。     

耐碳青霉烯类铜绿假单胞菌金属β-内酰胺酶和基因捕获元件基因检测及同源性分析

目的了解大连地区分离的耐碳青霉烯类铜绿假单胞菌的金属β-内酰胺酶、整合子I和ISCR1的分布情况,并分析其基因多态性特征。方法收集临床分离的89株耐亚胺培南铜绿假单胞菌,PCR检测金属酶、整合子I、ISCR1耐药基因。脉冲场凝胶电泳(PFGE)进行细菌基因分型。结果 89株亚胺培南耐药的铜绿假单胞菌中,ISCR1基因阳性菌25株(25/89,28%),其中84%(21/25)为多重耐药,5类及以上药物耐药的菌株占64%(16/25),金属酶基因阳性为11株(11/89,12%),其中有8株携带IMP-1基因,3株携带VIM-2,整合子I基因阳性43株(43/89,48%)。但携带金属酶的菌株整合子I、ISCR1基因扩增均为阴性;PFGE分型结果显示:89株耐亚胺培南的铜绿假单胞菌分为15个基因型(A~O),其中A型46株、B型16株、C型4株、D型5株、E型4株、F型3株、G型2株、H型2株,I型~O型各有1株。基因型集中的A型~G型,各型中的菌株来源于不同医院,呈多态性,每群均存在克隆株。结论基因捕获元件整合子I基因及ISCR1广泛分布在大连地区耐碳青霉烯类铜绿假单胞菌中,并与细菌的多重耐药、泛耐药显著相关,特别是ISCR1基因;大连地区整合子I、ISCR1并未携带金属酶基因盒。PFGE结果提示本地区铜绿假单胞菌具有基因多态性,但仍存在高度同源性的流行优势基因型。     

NDV HeB02分离株的生物学特性及其F基因的克隆与序列测定

对河北省新城疫分离株HeB0 2的生物学特性进行了鉴定 ,根据国外已发表的新城疫病毒F基因序列 ,设计了一对引物并以RT PCR特异性扩增出HeB0 2分离株的F基因 ,基因产物大小为 1 63kb ,与设计相符 ,对其进行序列测定后 ,与其它标准毒株F48E9、LaSota和Clone30的F基因进行同源性比较 ,结果表明 ,HeB0 2株与国内标准强毒株F48E9及目前广泛应用的弱毒疫苗LaSota和Clone30的F基因核苷酸序列的同源性分别为 88 1 %、84 9%和 83 8%,由此可以看出HeB0 2分离株与标准毒株和疫苗株在F基因上发生了变异。     

产ESBLs大肠埃希菌整合子及其相关基因盒的研究

目的检测产超广谱β-内酰胺酶（ESBLs）大肠埃希菌中整合子的整合酶及插入的相关基因盒情况,分析整合子对细菌耐药性的影响。方法采用K-B琼脂扩散法对45株临床分离的产ESBLs大肠埃希菌进行药敏试验;应用PCR法检测45株产ESBLs大肠埃希菌Ⅰ类、Ⅱ类和Ⅲ类整合子;对Ⅰ类整合子阳性菌进行整合子相关基因盒检测。结果45株菌中有27株（60．0％）含有Ⅰ类整合子,没有检测到Ⅱ类和Ⅲ类整合子阳性菌。在Ⅰ类整合子阳性菌中,有23株携带Ⅰ类整合子相关基因盒（85．2％）,5种不同的基因盒图谱,片段大小在600～2322bp,分离自同一科室的部分菌株携带大小相同的基因盒;Ⅰ类整合子阳性菌株的耐药率高于整合子阴性的菌株。结论Ⅰ类整合子及整合子相关基因盒在产ESBLs大肠埃希菌株中分布广泛,整合子在细菌耐药中发挥作用。     

NDV HeB02分离株的生物学特性及其F基因的克隆与序列测定*

对河北省新城疫分离株HeB02的生物学特性进行了鉴定 ,根据国外已发表的新城疫病毒F基因序列 ,设计了一对引物并以RT PCR特异性扩增出HeB02分离株的F基因 ,基因产物大小为 1.63kb ,与设计相符 ,对其进行序列测定后 ,与其它标准毒株F48E9、LaSota和Clone30的F基因进行同源性比较 ,结果表明 ,HeB02株与国内标准强毒株F48E9及目前广泛应用的弱毒疫苗LaSota和Clone30的F基因核苷酸序列的同源性分别为 88.1 %、84.9%和 83.8%,由此可以看出HeB0     

利用PCR技术快速检测根际产ACC脱氨酶细菌

通过产生ACC脱氨酶降低胁迫乙烯水平并缓解盐胁迫危害,是植物根际促生菌(PGPR)促进宿主生长和抗逆的重要机制。本研究提出了利用PCR技术快速检测产ACC脱氨酶细菌的快捷方法。以编码ACC脱氨酶的acd S基因为标记,分别使用acd Sf3/acd Sr4、Deg ACCf/Deg ACCr和F1936f/F1938r三对引物,对多种盐生植物和美洲黑杨(Populus deltoids)的根部及根际土中分离得到的细菌菌株进行检测。结果表明,结合acd Sf3/acd Sr4引物和递减PCR(touchdown-PCR)方法时,能获得单一的特异性扩增条带且扩增成功率高;但Deg ACCf/Deg ACCr和F1936f/F1938r两对引物特异性较差。从247个菌株中检测到25株含有acd S基因,旨为今后研究植物根际细菌acd S基因遗传性及储备丰富的功能性菌株奠定基础。     

ICU病区大肠埃希菌中qnr基因的分布与耐药性的研究

目的调查温州医科大学附属第一医院ICU病区分离的大肠埃希菌基因的分布以及与耐药谱的关系,并初步探讨其在分子流行病学中的作用。方法收集2012年1-9月ICU病区分离的大肠埃希菌76株进行qnr基因检测,并通过DNA直接测序确定;分析qnr基因在ICU病区分离的大肠埃希菌的分布及其与耐药性的关系。结果根据PCR产物片段大小及测序分析,76株大肠埃希菌中共有qm基因阳性菌株46株,阳性率为60. 5% ;对阳性菌株进行DNA测序、BLAST比对,其中25株为qnrB基因,17株为qnrS基因阳性,12株基因阳性,未检测到qwC和qnrD基因。在46株qnr基因阳性菌株中有38株为产ESBL菌株,而在qnr阴性菌株中仅有5株ESBL阳性。结论该院ICU分离大肠埃希菌qnr基因携带严重,呈现出多重耐药性,多伴随呈现为产ESBL菌株。     

Fluorescently labeled inhibitor for profiling cytoplasmic peptide:N-glycanase

Cytoplasmic peptide:N-glycanase (PNGase) is an enzyme that removes N-glycans from misfolded glycoproteins. The function of cytoplasmic PNGase plays a significant role in the degradation of misfolded glycoproteins, which is critical for cell viability. Recently, we reported that haloacetoamidyl derivatives of high-mannose-type oligosaccharides selectively modify the catalytic cysteine of cytoplasmic PNGase and serve as its specific inhibitor. Interestingly, a drastically simplified chloroacetamidyl chitobiose derivative [(GlcNAc)(2)-ClAc] was also reactive to PNGase. In our work, it was conjugated to a hydrophobic fluorophore in order to render (GlcNAc)(2)-ClAc cells permeable. We demonstrated that this compound [BODIPY-(GlcNAc)(2)-ClAc] specifically binds to cytoplasmic PNGase from budding yeast (Png1). To date, only Z-VAD-fmk is known as an inhibitor of PNGase. BODIPY-(GlcNAc)(2)-ClAc and Z-VAD-fmk share the same binding site on Png1, while BODIPY-(GlcNAc)(2)-ClAc has markedly stronger inhibitory activity. The functional analysis of PNGase using Z-VAD-fmk should be carefully interpreted because of its intrinsic property as a caspase inhibitor. In sharp contrast, chloroacetamidyl chitobiose was not reactive to caspase. In addition, BODIPY-(GlcNAc)(2)-ClAc did not bind either chitobiose-binding lectins or PNGase from other sources. Moreover, fluorescent microscopy clearly showed that BODIPY-(GlcNAc)(2)-ClAc was efficiently introduced into cells. These results suggest that this compound could be an in vivo inhibitor of cytoplasmic PNGase.     

拟南芥Peptide5和Peptide6的表达谱分析

摘要: 通过对5个拟南芥(Arabidopsis thaliana L.)预测性多肽进行RT-PCR分析, 在mRNA水平证实了Peptide5和Peptide6预测性多肽的真实性。表达谱分析表明: 两基因在不同的发育期和不同的组织普遍表达, 为组成型基因; 对NaCl、聚乙二醇4000(PEG4000)、茉莉酸甲酯(MeJA)、水杨酸(SA)、机械损伤和冷害做出基因转录水平的响应。启动子顺式作用元件分析提示, 拟南芥Peptide5基因可能参与了次生木质部的形成。     

Novel small molecule binders of human N-glycanase 1, a key player in the endoplasmic reticulum associated degradation pathway

Peptide:N-glycanase (NGLY1) is an enzyme responsible for cleaving oligosaccharide moieties from misfolded glycoproteins to enable their proper degradation. Deletion and truncation mutations in this gene are responsible for an inherited disorder of the endoplasmic reticulum-associated degradation pathway. However, the literature is unclear whether the disorder is a result of mutations leading to loss-of-function, loss of substrate specificity, loss of protein stability or a combination of these factors. In this communication, without burdening ourselves with the mechanistic underpinning of disease causation because of mutations on the NGLY1 protein, we demonstrate the successful application of virtual ligand screening (VLS) combined with experimental high-throughput validation to the discovery of novel small-molecules that show binding to the transglutaminase domain of NGLY1. Attempts at recombinant expression and purification of six different constructs led to successful expression of five, with three constructs purified to homogeneity. Most mutant variants failed to purify possibly because of misfolding and the resultant exposure of surface hydrophobicity that led to protein aggregation. For the purified constructs, our threading/structure-based VLS algorithm, FINDSITE^comb, was employed to predict ligands that may bind to the protein. Then, the predictions were assessed by high-throughput differential scanning fluorimetry. This led to the identification of nine different ligands that bind to the protein of interest and provide clues to the nature of pharmacophore that facilitates binding. This is the first study that has identified novel ligands that bind to the NGLY1 protein as a possible starting point in the discovery of ligands with potential therapeutic applications in the treatment of the disorder caused by NGLY1 mutants.     

N-糖蛋白去糖基化酶（PNGase）的研究进展

N-糖蛋白去糖基化酶（PNGase）是一种广泛存在于真菌、植物、哺乳动物中的去糖基化酶，可以水解N-糖蛋白或 N-糖肽上天冬酰胺与寡糖链连接的化学键，并释放出完整的N-寡糖。PNGase在生物体内参与蛋白质降解、器官发育、个体生长等过程。人PNGase基因功能缺陷会导致先天性去糖基化障碍，小鼠PNGase缺陷会导致胚胎致死性，线虫PNGase缺陷使其寿命下降。本文对PNGase在不同物种的分布、蛋白质结构、酶学功能及生物学功能进行阐述，为PNGase的生理病理功能及致病机制的基础研究提供思路，为PNGase作为糖生物学工具酶或药物开发的创新应用研究奠定基础。     

Structural Analysis of Free N-Glycans Occurring in Soybean Seedlings and Dry Seeds

The structures of unconjugated or free N-glycans in stems of soybean seedlings and dry seeds have been identified. The free N-glycans were extracted from the stems of seedlings or defatted dry seeds. After desalting by two kinds of ion-exchange chromatography and a gel filtration, the free N-glycans were coupled with 2-aminopyridine. The resulting fluorescence-labeled (PA-) N-glycans were purified by gel filtration, Con A affinity chromatography, reverse-phase HPLC, and size-fractionation HPLC. The structures of the PA-sugar chains purified were analyzed by the combination of two-dimensional sugar chain mapping, jack bean α-mannosidase digestion, α-1,2-mannosidase digestions, partial acetolysis, and ESI-MS/MS. The free N-glycan structures found showed that two categories of free N-glycans occur in the stems of soybean seedlings. One is a high-mannose type structure having one GlcNAc residue at the reducing end (Man_9~5GlcNAc₁, 93%), that would be derived by endo-GM (Kimura, Y. et al., Biochim. Biophys. Acta, 1381, 27-36 (1998)). The other small component is a xylose-containing type one having two GlcNAc residues at the reducing end (Man₃Xyl₁GlcNAc₂, 7%), which would be derived by PNGase-GM (Kimura, Y. and Ohno, A., Biosci. Biotechnol. Biochem., 62, 412-418 (1998)). The detailed structural analysis of free glycans showed that high-mannose type free N-glycans (Man_9~5GlcNAc₁) in the soybean seedlings have a common core structural unit; Manα1- 6(Man1-3)Manα1-6(Manα1-3)Manβ1-4GlcNAc.

Comparing the amount of free N-glycans in the seedling stems and dry seeds, the amount in the stems of seedlings was much higher than that in the dry seeds; approximately 700 pmol per one stem, 8 pmol in one dry seed. This fact suggested that free N-glycans in soybean seedlings could be produced by two kinds of N-glycan releasing enzymes during germination or seedling-development.     

Discovery and optimization of pseudopeptide leads towards peptidomimetic drugs

Summary Progress in the identification of primary leads is increasingly obtained by the production of molecular diversity via the synthesis of peptide and non-peptide libraries. In this review, statistical considerations are made about the feasibility and reliability of peptide libraries. It is shown that the number of beads per peptide engaged in synthesis controls the relative concentration of any two peptide types, while the total amount of resin determines the feasibility of the complete library in relation to peptide size. Molecular modelling is used to estimate the conformational diversity. A preliminary analysis of libraries by NMR, MS, MS/MS and capillary electrophoresis is advocated. Examples are given of optimized peptide leads in hirudin, neurokinin, bradykinin and angiopeptin series. Finally, the relative effect of hydrogen-bond potential and overall lipophilicity on oral absorption is evaluted on neurokinin-1 and endothelin-1 receptor antagonists.     

USF-19A,a New Lipoxygenase Inhibitor from Streptomyces sp.

USF-19A, a soybean Jipoxygenase (SBL) and human 5-lipoxygenase (5-LO) inhibitor, was isolated from Streptomyces sp. USF-19 strain. Its chemical structure was determined by spectroscopic evidence to be a new member of the antimycin antibiotic family. The IC₅₀ value of USF-19A against 5-LO was 28.0 μM.     

A New Peptide-N 4-(acetyl-β-glucosaminyl)asparagine Amidase from Soybean (Glycine max) Seeds: Purification and Substrate Specificity

We report here the isolation and characterization of a peptide-N ⁴-(acetyl-β-glucosaminyl) asparagine amidase (peptide: N-glycanase) from soybean (Glycine max) seeds. The enzyme was purified to homogeneity with 6.5% yield from defatted soybean meal extract by ion-exchange chromatography, gel filtration, hydroxyapatite chromatography, and hydrophobic chromatography. The purified enzyme, designated PNGase-GM, had the apparent molecular mass of 93 kDa by SDS-PAGE and 90 kDa by gel filtration, indicating this PNGase is a monomeric protein. The enzyme showed maximal activity at pH 4.5-5.0. PNGase-GM was capable of hydrolyzing the β-aspartylglycosylamine linkage (GlcNAcβ1→Asn) of various glycopeptide substrates bearing high-mannose type, hybrid type, and xylose/fucose-containing plant complex type N-glycan units, while this amidase was far less active on the glycopeptides bearing sialylated animal complex-type glycans.     

Peptide chemistry toolbox – Transforming natural peptides into peptide therapeutics

The development of solid phase peptide synthesis has released tremendous opportunities for using synthetic peptides in medicinal applications. In the last decades, peptide therapeutics became an emerging market in pharmaceutical industry. The need for synthetic strategies in order to improve peptidic properties, such as longer half-life, higher bioavailability, increased potency and efficiency is accordingly rising. In this mini-review, we present a toolbox of modifications in peptide chemistry for overcoming the main drawbacks during the transition from natural peptides to peptide therapeutics. Modifications at the level of the peptide backbone, amino acid side chains and higher orders of structures are described. Furthermore, we are discussing the future of peptide therapeutics development and their impact on the pharmaceutical market.