4,5-双氢-7-去氨甲酰基-7-羟基-19-S-甲基格尔德霉素及其与格尔德霉素生物合成PKS后修饰的关系

目的在吸水链霉菌17997格尔德霉素生物合成PKS后修饰gdmN-变株发酵产物中寻找新格尔德霉素衍生物。方法 gdmN-变株发酵上清液乙酸乙酯提取后,进行硅胶板TLC分析;对一个红色目标化合物进行了HPLC和高分辨质谱分析,并对其进行了1H-和13C-核磁共振(NMR)分析;对红色目标化合物在吸水链霉菌17997格尔德霉素PKS基因阻断变株中进行了生物转化实验。结果在gdmN-变株发酵产物中发现了1个预期的红色目标化合物(4,5-双氢-7-去氨甲酰基-7-羟基-19-S-甲基格尔德霉素);该目标化合物可被格尔德霉素生物合成PKS后修饰系统7-O-氨甲酰化,生成4,5-双氢-19-S-甲基格尔德霉素。结论在gdmN-变株中发现了4,5-双氢-7-去氨甲酰基-7-羟基-19-S-甲基格尔德霉素;该化合物可被格尔德霉素PKS后修饰系统继续7-O-氨甲酰化,但不能C-4,5氧化。     

吸水链霉菌17997产生的4，5-双氢格尔德霉素的鉴别与检测

本文对从吸水链霉菌17997发酵提取获得的格尔德霉素精制品进行了LC-MS-MS分析,发现其中含有4,5-双氢格尔德霉素组分.对吸水链霉菌17997摇瓶发酵产物的硅胶板薄层层析分析表明,4,5-双氢格尔德霉素组分在发酵中期有积累.已知4,5-双氢格尔德霉素的抗肿瘤活性比格尔德霉素差,因而需要限制其在格尔德霉素制品中的含量.本文研究结果对以吸水链霉菌17997等为产生菌研究格尔德霉素发酵,促进4,5-双氢格尔德霉紊转化为格尔德霉素以提高发酵液的品质,以及检测格尔德霉素制品中的4,5-双氢格尔德霉素组分具有实际意义.     

苯安莎类抗生素的一种早期鉴别方法

目的建立一种对苯安莎类抗生素特异的颜色反应早期鉴别方法。方法根据碱性处理苯安莎类抗生素，使其安莎链与苯环连接的酰胺键开裂后化合物呈紫色的原理，建立了将发酵液粗提品进行薄层色谱层析后采用2．0mol／LNaOH溶液喷涂显色的早期鉴别方法；以格尔德霉素为例，在硅胶板上的检测灵敏度为4μg。结论采用该颜色鉴别反应方法：①对两株确证为新的格尔德霉素产生菌Streptomyces sp．4-4以及Streptomyces sp．3-57进行了佐证；②对吸水链霉菌Streptomyces hygroscopicus 17997的一株格尔德霉素生物合成后修饰基因阻断变株CT-1中产生的格尔德霉素前体物及其类似物，在硅胶板上进行了快速定位和初步鉴别。     

高效液相色谱质谱法测定格尔德霉素基因阻断变株产物

目的:在研究格尔德霉素(GDM)生物合成的过程中利用基因阻断技术分别阻断 GDM 生物合成的起始基因3-氨基-5-羟基苯甲酸(AHBA)基因、含 AHBA 基因并与之相连的聚酮合酶(PKS)基因簇以及 GDM 生物合成相关的 PKS 和 PKS 后修饰基因簇 CT-PKS 获得3个 GDM 基因阻断变株。为了比较分析他们的次级代谢产物,采用高效液相色谱质谱法测定发酵液组分。方法:发酵液经过乙酸乙酯提取后用反相高效液相色谱分析。分析柱为迪马公司 Diamonsil~(TM)(钻石)C_(18)(4.6 mm×150 mm,5μm);流动相是40%～100%甲醇,30 min 梯度洗脱;流速1 mL·min~(-1);二极管阵列检测器(DAD),检测波长304nm。利用电喷雾质谱(ESI)通过正负离子扫描获得相应化合物的相对分子质量信息;利用质谱的源内裂解技术获得相应化合物的结构信息。结果:检测发现,阻断2个不同的 GDM 生物合成基因以后主要产生2个不同于 GDM 的化合物。结论:该方法可快速、准确地对基因工程变株发酵新产物进行早期鉴别,指引后续的化学分离,并用于其他 GDM 基因阻断变株产物的定性。     

格尔德霉素发酵工艺的优化

目的研究格尔德霉素产生菌吸水链霉菌SIPI.A.2039的发酵工艺,以提高产生菌生物合成格尔德霉素的能力。方法以本实验室保藏的吸水链霉菌SIPI.A.2039为出发菌株,从摇床转速、摇瓶装量、碳源、50L发酵罐参数等方面进行发酵工艺的优化研究。结果采用经过优化获得的发酵培养基和培养条件,发酵周期为144h时,格尔德霉素的摇瓶发酵效价可由原来的230μg/mL提高至2500μg/mL。在50L发酵罐中采用优化的溶解氧和补料工艺能够使格尔德霉素的发酵效价达到3700μg/mL,并使发酵周期比摇瓶缩短了48h。结论本实验得到的结果比国内外报道的格尔德霉素的发酵效价提高了两倍以上,该发酵工艺已经达到了产业化的要求。     

不吸水链霉菌中沉默基因簇的激活和产物结构鉴定

不吸水链霉菌S.ahygroscopicus S91(CGMCC4.7082)的次级代谢产物中含有多种抗真菌组分，目前已发现的组分有四霉素、制霉菌素、丰加霉素、白诺菌素和茴香霉素。通过生物信息学分析，不吸水链霉菌S91基因组中含有云南霉素和谷氏菌素的生物合成基因簇，但目前在该菌株发酵产物中并没有检测到这两种抗生素的存在。对四霉素、制霉菌素、丰加霉素生物合成阻断株Streptomyces ahygroscopicus ΔttmS1ΔnysBΔtymH进行发酵培养，发现其发酵液中具有水溶性的抑制黑曲霉的活性组分。以抑菌活性跟踪目标未知抑菌化合物，发酵液经离心、草酸酸化后，上清液经大孔吸附树脂DM-2脱色，脱色液经732阳离子交换、中性氧化铝柱柱层析和Sephadex LH-20色谱分离，最终得到两个具有抗真菌的化合物A和B。化合物经紫外、质谱和核磁进行结构鉴定，化合物A为云南霉素，B为谷氏菌素或宁南霉素。生物信息学分析与分离纯化技术相结合，进一步证实该菌株具有产生云南霉素和谷氏菌素抗生素的能力。     

四霉素A组分高含量基因工程菌的构建

目的通过阻断不吸水链霉菌S91中的四霉素生物合成途径P450单加氧酶基因ttm D,获得四霉素A组分高含量基因工程菌株。方法构建大肠杆菌-链霉菌穿梭重组质粒p KC-D3,通过接合转移将缺失592 bp的ttm D基因以双交换的方式置换不吸水链霉菌S91染色体的ttm D基因,采用摇瓶发酵,采用HPLC检测发酵液中四霉素的组分含量。结果 ttm D基因阻断菌株不吸水链霉菌S91-D不再产生四霉素B,获得了四霉素A高含量的菌株,四霉素A产量提高了47%。结论将不吸水链霉菌S91中的ttm D基因失活,可以阻断四霉素A生成四霉素B,从而提高四霉素A的含量及产量。     

新型强效免疫抑制剂雷帕霉素的生物合成

雷帕霉素是吸水链霉菌产生的新型强效免疫抑制剂,本文综述了雷帕霉素的生物合成,探讨了雷帕霉素构成单元、相关酶及雷帕霉素效价三者之间的关系,指出以雷帕霉素生物合成相关酶或前体含量为指标可能是筛选雷帕霉素高产突变株的又一途径。     

黑暗链霉菌中安普霉素生物合成的阻断研究

以黑暗链霉菌Tt-49基因组为模板,利用PCR方法,扩增安普霉素生物合成关键基因aprH～M的上、下游序列,作为同源交换臂,并以温敏复制型质粒pKC1139为基础,构建用于阻断黑暗链霉菌Tt-49中安普霉素生物合成的重组质粒pHM106.质粒经接合转移进入黑暗链霉菌Tt-49,并筛选得到发生同源双交换工程菌,命名为黑暗链霉菌HM106.通过PCR鉴定,证明工程菌HM106中的aprH～M被tetr替换.对工程菌HM106进行发酵产物分析,结果是其发酵效价下降明显,仅为出发菌株的40％左右.采用薄层层析(TLC)对其组分分析,其安普霉素组分消失,因此,初步判断已成功阻断安普霉素的生物合成.     

一个从吡啶霉素产生菌NRRLB-2517中分离鉴定的新异黄酮苷

目的 研究吡啶霉素(pyridomycin)在吡啶霉素链霉菌(Streptomyces pyridomyceticus NRRL B-2517)中生物合成的可能中间体.方法 大批量发酵吡啶霉素链霉菌,发酵液经乙酸乙酯萃取、反相硅胶柱层析、凝胶柱层析和半制备高效液相色谱分离获得单体,通过质谱和核磁共振进行波谱分析.结果 分离得到目的化合物WT-1.结论 经波谱分析,WT-1为一个新结构化合物7-O-α-L-鼠李糖染料木黄酮苷,从WT-1的化学结构及其可能的生物合成机制推测,WT-1与吡啶霉素的生物合成并无直接关联.     

Eicosanoid transcellular biosynthesis: from cell-cell interactions to in vivo tissue responses

The biosynthesis of the biologically active metabolites of arachidonic acid involves a number of enzymes that are differentially expressed in cells. Prostaglandins and thromboxanes are derived from the chemically unstable prostaglandin (PG) H(2) intermediate synthesized by PGH synthases (cyclooxygenase-1/2) and leukotrienes from chemically unstable leukotriene A(4) by 5-lipoxygenase. Additional enzymes transform these reactive intermediates to a variety of chemical structures known collectively as the lipid mediators. Although some cells have the complete cassette of enzymes required for the production of biologically active prostaglandins and leukotrienes, the actual biosynthetic events often are a result of cell-cell interaction and a transfer of these chemically reactive intermediates, PGH(2) and leukotriene A(4), between cells. This process has come to be known as transcellular biosynthesis of eicosanoids and requires a donor cell to synthesize and release one component of the biosynthetic cascade and a second, accessory cell to take up that intermediate and process each into the final biologically active product. This review focuses on the evidence for transcellular biosynthetic events for prostaglandins, leukotrienes, and lipoxins occurring during cell-cell interactions. Evidence for arachidonic acid serving as a transcellular biosynthetic intermediate is presented. Experiments for transcellular events taking place in vivo that reveal the true complexity of eicosanoid biosynthesis within tissues are also reviewed.     

妊娠期糖尿病患者胎盘和腹部皮下脂肪组织中脂联素受体2的表达分析

目的 探讨脂联素受体2 (adioponectin receptor2,AdipoR 2)在妊娠期糖尿病患者胎盘及腹部皮下脂肪组织中的表达情况.方法 收集正常妊娠妇女及妊娠期糖尿病患者各20例皮下脂肪组织及胎盘组织,分别采用逆转录聚合酶链反应技术(RT-PCR)及蛋白免疫印迹法(Western bolt)检测AdipoR 2 mRNA及其蛋白质的表达情况.结果 与正常妊娠妇女相比较,妊娠期糖尿病患者胎盘组织中AdipoR 2 mRNA及其蛋白质表达均升高,皮下脂肪组织中AdipoR2 mRNA及其蛋白质表达均降低.结论 AdipoR2在胎盘组织及皮下脂肪组织中表达异常,可能在妊娠期糖尿病的发病机制中起到重要作用.     

Studies on the biosynthesis of basic 16-membered macrolide antibiotic, platenomycins. I. Selection of and cosynthesis by non-platenomycin-producing mutants.

In a search for blocked mutants which may produce a biosynthetic intermediate, mutation by N-methyl-N'-nitro-N-nitrosoguanidine treatment and/or ultra-violet irradiation were performed on platenomycin-producing Streptomyces platensis subsp. malvinus MCRL 0388 (NRRL 3761). Twenty four non-platenomycin-producing stable mutants were thus obtained and tested for cosynthesis ability. Antibiotic cosynthesis with a pair of these mutants made it possible to detect the producer of an intermediate. Among these mutants which were classified into eight groups (A to G and doubtful groups), mutants of groups A and B appeared from their complementation pattern to be the useful producers of biosynthetic intermediates of platenomycin.     

Effects of antidiabetic agents on pancreatic beta-cell function in gestational diabetes: is there enough evidence?

Gestational diabetes mellitus (GDM) is typically characterized by the presence of insulin resistance. However, recent studies showed that both insulin resistance and pancreatic beta-cell function impairment may contribute to the development of type 2 diabetes in women with history of GDM. In fact, beta-cell function decline was found as significant predictor of later disease in former GDM women progressing towards type 2 diabetes. Despite the evidence of the relevance of beta-cell function quantification in GDM, a low number of studies focused on the effects of GDM treatments on beta-cell function. We briefly present the evidence of the effects on beta-cell function of pharmacological agents, as well as nutrition supplements or medical nutrition therapy, used in the management of GDM. We found that few studies reported information on beta-cell function effects in GDM, despite some agents, such as glyburide, are well known insulin secretagogues. Therefore, further studies should be carried out to clearly assess the effects on beta-cell function of the treatments in GDM women.     

格尔德霉素体内外抑制单纯疱疹病毒l型的复制

格尔德霉素(GA)是一种抗生素,它的作用靶点是热休克蛋白Hsp90 N末端的ATP/ADP结合位点.在我们对抗病毒的抗生素筛选中,发现格尔德霉素显著抗单纯疱疹病毒1型(HSV一1).体外在Vero细胞内GA显著抑制HSv-1的复制,IC50为0,093μmol/L,GA对Vero细胞的毒性CC50为350μmol/L,治疗指数可达3763.HSV-1腹腔(ip)感染1h后腹腔(ip)注射GA(0.093～0.37mg/kg)可以将存活率增加到67%～100%,皮下(sc)给药(0.37mg/kg)的存活率为43.8%,都明显高于生理盐水对照组(ipP＜0.001.scP＜0.05).GA对小白鼠的急性LD50为15.5mg/kg(ip).格尔德霉素不影响病毒的吸附、穿人.由于GA在体内外都能抑制单纯疱疹病毒1型,GA可以成为新的抗单纯疱疹病毒感染的药物.     

Isolation and structure of a new macrolide antibiotic,erythromycin G,and a related biosynthetic intermediate from a culture of Saccharopolyspora erythraea

The new naturally occurring erythromycin G (4), formally derived from erythromycin B by hydroxylation of the C-16 methyl group, and 3-O-mycarosylerythronolide B (5), an erythromycin biosynthetic intermediate previously obtained only from microorganisms blocked in erythromycin biosynthesis, were isolated from a concentrate of mother liquors derived from a culture of Saccharopolyspora erythraea. The structure of erythromycin G was defined by spectroscopic data and X-ray crystallographic analysis. Theoretical calculation of 4 has been performed at MM2 level, and the low-energy conformations have been compared with X-ray data: both theoretical and experimental approaches give similar three-dimensional shapes. Antibacterial activity of 4 against both gram-positive and gram-negative organisms has been evaluated. A simple method for the isolation of large amounts of erythromycins B (2) and D is provided as well.     

Biosynthesis of chrysomycins A and B. Origin of the chromophore

The biosynthetic origin of the carbon atoms in the chromophores of chrysomycins A and B was investigated in feeding experiments using 13C labeled acetates and propionate. A biosynthetic scheme is proposed involving the condensation and rearrangement of a decaketide intermediate which contains either propionate (chrysomycin A) or acetate (chrysomycin B) as the chain initiator.     

观察门冬胰岛素和生物合成人胰岛素对妊娠期糖尿病(GDM)血糖控制与并发症的影响

目的:探讨门冬胰岛素和生物合成人胰岛素对妊娠期糖尿病(GDM)血糖控制与并发症的影响.方法:通过对2018年2月～2019年12月在某院治疗126例妊娠期糖尿病患者分组,分为对照组和实验组,对照组采用生物合成人胰岛素治疗,实验组采用门冬胰岛素和生物合成人胰岛素治疗,观察比较两组血糖水平、血清氧化物水平、母婴结局、不良反...