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1.
王不留行环肽研究   总被引:9,自引:2,他引:7  
从中药王不留行(Vacariasegetalis)种子中分离并鉴定了4个环肽化合物,分别命名为王不留行环肽A,B,C,D(vaccarinsA,B,C,D),其中王不留行环肽A为新环肽化合物。其结构通过光谱和化学方法分别确定为:vaccarinA——cyclo-(Trp-Ala1-Gly-Val-Ala2),vaccarinB———cyclo-(Pro-Gly-Leu-Ser-Phe1-Ala-Phe2),vaccarinC———cyclo-(Pro1-Gly-Tyr-Val-Pro2-Leu-Trp),vacarinD———cyclo-(Pro-Val1-Trp-Ala-Gly-Val2).  相似文献   

2.
金铁锁根中的环肽成分   总被引:25,自引:0,他引:25  
从云南民间重要的药用植物金铁锁(Psammosilene tunicoides W.C.Wu et C.Y.Wu)的根中分离得到2个新的天然环二肽以及2个新的环八肽:金铁锁环肽A和B(psammosilenins A and B)。它们的结构经光谱方法鉴定为cyclo(-Ala-Ala-),cyclo(-Val-Ala-),cyclo(-Pro1-Phe1-Pro2-Phe2-Phe3-Ala-p  相似文献   

3.
千针万线草环肽A的结构修正   总被引:4,自引:1,他引:3  
从云南民间药物千针万线草(Stellaria yunnanensis)的根中分离到一新环肽stellarinA。前报主要利用快速原子轰击质谱确定其结构为cyclo(Gly-Pro-Phe-Tyr-Gly-Gly-Pro)。最近利用最新二维核磁结合快速原子轰击质谱及酶降解重新考察了其结构,修正为cyclo(Gly-Pro-Phe-Pro-Gly-Tyr-Gly)。  相似文献   

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从织锦芋螺中克隆α芋螺毒素序列   总被引:13,自引:0,他引:13  
为了从我国南海产织锦芋螺(Conustextile)中分离新的毒素序列并研究其应用价值,进行了织锦芋螺毒素基因的分离工作.从织锦芋螺毒管中提取mRNA,以A族芋螺毒素的信号肽编码部分和3′端非翻译部分的保守序列为引物,通过RT-PCR扩增和序列分析方法获得新的芋螺毒素序列.结果得到两种不同的α芋螺毒素序列,两者都属于α4/7亚型芋螺毒素,预测其成熟肽序列分别为Pro-Glu-Cys-Cys-Ser-Asp-Pro-Arg-Cys-Asn-Ser-Ser-His-Pro-Glu-Leu-Cys-Gly(C端Gly可能被酰胺化)和Pro-Glu-Cys-Cys-Ser-His-Pro-Ala-Cys-Asn-Val-Asp-His-Pro-Glu-Ile-Cys-Arg.采用传统的生化分离手段尚未从织锦芋螺中获得过α芋螺毒素序列,这两种α芋螺毒素作用的种属特异性、受体类型特异性和在小细胞肺癌的诊断和治疗中的应用价值有待进一步研究  相似文献   

5.
为了研究胰岛素受体结合部位的结构和功能,设计并用固相方法合成了3个六肽.在浓度大于1×103nmol/L时,cyclo(Phe-Phe-Val-Leu-Tyr-Gly)具有明显的胰岛素受体结合活力;H-Phe-Phe-Val-Leu-Tyr-Gly-OH的这一活力则不明显;而H-Gly-Glu-Arg-Gly-Phe-Phe-OH则增强胰岛素和其受体的亲和性.然而,它们都没有体内生物活性.这表明:环六肽部分模拟了胰岛素受体结合部位的空间构象;胰岛素受体结合部位的疏水性和其中的B23Gly-B24Phe-B25Phe对胰岛素和其受体的结合起重要作用.  相似文献   

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至今已发现了四种锌指蛋白(Zfp)。Ⅰ型为Cys-X2-4-Cys-X3-Phe-X5-Leu-X2-His-X3-His,简写C2H2。TFⅢA为C2H2×9,即9个锌指的重复单位。Sp1为C2H2×3。目前已发现有1000种以上具有Ⅰ型锌指同源保...  相似文献   

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凤眼莲(Eichhorniacrassipes)的根分泌物中含有Met等多种氨基酸,其中Met、GABA、Gly、Ala、Asp、Ser、Val和Leu(10-7~10-2mol·L-1)均对凤眼莲的根际肠杆菌属F2(Enterobactersp.F2)细菌有强烈的正趋化作用;Glu、Thr和His(10-7~10-3mol·L-1)也对该菌有一定的正趋化作用;而Lys、Cys、Arg、Tyr、Pro、Asn、Gln、Ile、Phe和Typ则对该菌表现出一定的负趋化作用.对细菌的正趋化作用存在一个趋化物的最适浓度范围.具有正趋化作用的氨基酸在凤眼莲根际的浓度都较高,而具有负趋化作用的浓度则较低,这正是凤眼莲与该根际细菌结合为根际微生态系统的原因之一.  相似文献   

8.
少棘巨蜈蚣(ScolopendrasubspinipesmutilansL.Koch)经95%乙醇脱脂后,再经4℃水冷渗,水提液低温旋转浓缩,冻干,得到的冻干粉先后经过SephadexG-25柱,等电聚焦制备电泳,再经SephadexG-150柱,SephadexG-100柱,最后经HPLC制备得到一个纯的碱性蛋白,命名为SSmp-d.该蛋白经HPLC、超薄等电聚焦电泳检验是均一的.采用HPLC和Protein-PakTM125柱测定其分子量为24.64kD.IEF-HPCE显示其等电点为9.27.氨基酸分析表明SSmp-d含较多的Arg、Lys等碱性氨基酸,另外还含有较多的Ala、Leu.使用蛋白质自动序列分析仪测定了SSmp-dN端的11个氨基酸,序列为NH3+-Asp-Val-Asn-Phe-Arg-Leu-Ser-Gly-Ala-Asp-Pro.  相似文献   

9.
农业系统生产力(ASP)的量化及其现状分析   总被引:6,自引:0,他引:6  
农业系统生产力(ASP)的量化及其现状分析卢进登,韩纯儒(北京农业大学农学系,100094)QuantificationofAgrosystemProductivity(ASP)andAnalysisonitsCurrentSituationinCbina¥.LuJin-deng;HanChunru(BeijingAgriculturalUniversityfBeijing100094).ChineseJournalofEcology,1993,12(2):21-22.BasedonabriefanalysisontheformationprocessofASP,itsconceptisdescribedandanintegratedindi-catorforitsquantification—ASP2isputforwards.Fromthose,theASPlevelsinvariousregionsofChinaareanalyzedand8levelsaredividedbyusing.Hierarchicclusteringmethod.It’s:clarifiedthatAS-PIisamore  相似文献   

10.
湖北省吨粮田的现状及其投肥效率分析孙先(华中农业大学,武汉430070)CurrentSituationandFertilizationEfficiencyofHighProductiveCroplandsinHubeiProvince¥SunXian-rong(CentralChinaAgricultureUniversity,Wuhan430070).ChineseJournalofEcologyl1993,12(2):55-56.Since1990,thedevelopmentofhighproductivecroplandhasbeenacceleratedandtheeffectofitsyieldandbenefitincreaseisveryobvious,But,whetherhighyieldandhighefficiencycanbesynchronizedde-servescloseattention,Inthisresearch,79highyieldcroppingpatternsareinvestigatedforthreeyearsinHubeiandtheirefficien  相似文献   

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Comprises species occurring mostly in subtidal habitats in tropical, subtropical and warm-temperate areas of the world. An analysis of the type species, V. spiralis (Sonder) Lamouroux ex J. Agardh, a species from Australia, establishes basic characters for distinguishing species in the genus. These characters are (1) branching patterns of thalli, (2) flat blades that may be spiralled on their axis, (3) width of the blade, (4) primary or secondary derivation of sterile and fertile branchlets and (5) position of sterile and fertile branchlets on the thalli. Application of the latter two characters provides an important basic method for separation of species into three major groups. Osmundaria , a genus known only in southern Australia, was studied in relation to Vidalia , and its separation from the Vidalia assemblage is not accepted. Species of Vidalia therefore are transferred to the older genus name, Osmundaria. Two new species, Osmundaria papenfussii and Osmundaria oliveae are described from Natal. Confusion in the usage of the epithet, Vidalia fimbriala Brown ex Turner has been clarified, and Vidalia gregaria Falkenberg, described as an epiphyte on Osmundaria pro/ifera Lamouroux, is revealed to be young branches of the host, Osmundaria prolifera.  相似文献   

16.
Fifteen chromosome counts of six Artemisia taxa and one species of each of the genera Brachanthemum, Hippolytia, Kaschgaria, Lepidolopsis and Turaniphytum are reported from Kazakhstan. Three of them are new reports, two are not consistent with previous counts and the remainder are confirmations of very scarce (one to four) earlier records. All the populations studied have the same basic chromosome number, x = 9, with ploidy levels ranging from 2x to 6x. Some correlations between ploidy level, morphological characters and distribution are noted.  相似文献   

17.
Curcumin is the yellow pigment of turmeric that interacts irreversibly forming an adduct with thioredoxin reductase (TrxR), an enzyme responsible for redox control of cell and defence against oxidative stress. Docking at both the active sites of TrxR was performed to compare the potency of three naturally occurring curcuminoids, namely curcumin, demethoxy curcumin and bis-demethoxy curcumin. Results show that active sites of TrxR occur at the junction of E and F chains. Volume and area of both cavities is predicted. It has been concluded by distance mapping of the most active conformations that Se atom of catalytic residue SeCYS498, is at a distance of 3.56 from C13 of demethoxy curcumin at the E chain active site, whereas C13 carbon atom forms adduct with Se atom of SeCys 498. We report that at least one methoxy group in curcuminoids is necessary for interation with catalytic residues of thioredoxin. Pharmacophore of both active sites of the TrxR receptor for curcumin and demethoxy curcumin molecules has been drawn and proposed for design and synthesis of most probable potent antiproliferative synthetic drugs.  相似文献   

18.
正Dear Editor,In December 2019, a novel human coronavirus caused an epidemic of severe pneumonia(Coronavirus Disease 2019,COVID-19) in Wuhan, Hubei, China(Wu et al. 2020; Zhu et al. 2020). So far, this virus has spread to all areas of China and even to other countries. The epidemic has caused 67,102 confirmed infections with 1526 fatal cases  相似文献   

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