大麦Dhn6基因的克隆、蛋白质结构预测与干旱胁迫表达模式

脱水素(Dehydrins,DHNs)是高等植物胚胎发育晚期产生的一类特异多肽,其表达累积程度与植物的发育阶段、低温、ABA和脱水信号调节等因素密切相关。为了解脱水素的结构与干旱胁迫表达累积反应,文章从六棱大麦分离到序列全长为1 767 bp的Dhn6基因,序列分析结果表明,该基因含一个92 bp内含子,90~1 759 bp为一个开放阅读框,与裸大麦Dhn6基因(GenBank登录号:AF043091)的同源性最高,达93.18%,编码523个氨基酸残基的多肽,预测蛋白质的分子量为49.68 kDa,理论等电点为8.04。结构分析发现,蛋白质具有3个螺旋区,无规则卷曲构成二级结构的主要组分,亲水氨基酸比例超过83%;三维结构预测发现,多肽链自身反向平行排列成松散的亲水索链,K-片段参与兼性?-螺旋结构域的形成,意味着该脱水素具有束缚自由水、稳定细胞膜相结构的功能。实时定量RT-PCR检测结果表明,Dhn6基因的相对表达水平在干旱处理8 h快速累积,推测DHN6在大麦对干旱胁迫的早期响应中发挥重要功能。     

沙冬青脱水素基因的分子克隆与序列分析

脱水素(Dehydrin)是晚期胚胎发生蛋白(LEA)家族中最具特色的一组蛋白,对植物抵抗非生物逆境胁迫起到非常重要的作用。本研究从抗逆性较强的常绿阔叶灌木沙冬青中克隆出4个含有完整ORF的脱水素基因,命名为AmDHN3.2F、AmDHN5.1F、AmDHN6.2F和AmDHN7.2,并进行了相关生物信息学分析。使用DNAMAN软件预测结果显示,4个蛋白都含有一个K片段和S片段。理化性质分析表明,4种脱水素蛋白均为亲水性蛋白,其中AmDHN3.2F为碱性蛋白,AmDHN5.1F、AmDHN6.2F和AmDHN7.2为酸性蛋白;理论相对分子质量最大的是AmDHN7.2(21.42kD),最小的是AmDHN3.2F(10.69kD);理论等电点最大的是AmDHN3.2F(9.01),最小的是AmDHN6.2F(6.21)。蛋白二级和三级结构预测结果发现,4种蛋白均由3种结构组成:α-螺旋(7.50%～32.63%)、无规则卷曲(55.79%～73.00%)和延伸链(11.58%～19.50%)。采用邻接法构建系统进化树,并结合同源相似性分析发现,4种脱水素蛋白均与蒺藜苜蓿Mt DHN3和拟南芥At DHN10亲缘关系较近。利用XSTREAM软件分析结果显示,Am DHN5.1F、Am DHN6.2F和Am DHN7.2第3个蛋白序列具有串联重复单元,且主要集中在脱水素的中间部分。通过DOTTER软件生成点阵图发现,在中间区域存在大量的短片段重复,说明脱水素序列的收缩或扩张主要发生在中间部分。这些研究结果为进一步开展沙冬青DHN基因家族的功能分析奠定了基础。     

苏太猪ELOVL7基因的生物信息学分析

不同于人、鼠等物种ELOVL7基因的高相似度,不同品种的猪ELOVL7基因相似度较低。为了探究该基因的特性,本研究运用生物信息学的方法对苏太猪ELOVL7基因及其氨基酸序列的同源性、理化性质、保守结构域、亚细胞定位、信号肽、跨膜结构域、亲水性/疏水性、二级结构、功能预测以及磷酸化位点等进行预测分析。结果表明：在苏太猪中,ELOVL7全长2 324 bp,编码区为846 bp,共编码281个氨基酸。其结构稳定,分子量为33 387.4 Da,带正电荷,偏碱性。该基因所编码的蛋白质最可能位于细胞膜上,主要的功能是运输和结合,为跨膜、非分泌型疏水蛋白质,含有1个GNS1/SUR4家族的保守结构域,并有15个丝氨酸激酶、15个苏氨酸激酶和20个酪氨酸激酶潜在磷酸化位点。α螺旋是ELOVL7二级结构和三级结构中最主要的结构元件。另外ELOVL7与大部分物种的氨基酸序列相似性达90%以上,且亲缘关系较近。分析ELOVL7基因及其氨基酸序列的特征,能够为进一步挖掘该基因内的突变对长链脂肪酸表型的影响以及合成、代谢机理提供分子依据。     

双峰驼凝乳酶原基因的生物信息学分析

通过生物信息学的方法对双峰驼凝乳酶原基因及相应的氨基酸序列的同源性、理化性质、保守结构域、亚细胞定位、信号肽、跨膜结构域、亲水性/疏水性、二级结构进行预测分析.结果表明,双峰驼凝乳酶原基因开放阅读框全长1 146 bp,编码381个氨基酸,属于胃蛋白酶A超家族,预测定位于内质网（膜）的稳定亲水性蛋白,具有一个16个氨基酸的信号肽,其不含跨膜结构域.无规卷曲是其二级结构中最大量的结构元件,α螺旋和延抻链分散于整个蛋白质中,活性位点的分析表明,编码蛋白有6类活性位点.分析双峰驼凝乳酶原基因及其编码蛋白质的特征,能够为深入开展双峰驼凝乳酶的表达和凝乳特性研究提供理论依据.     

鸭FTO基因多态位点筛选和生物信息学分析

为挖掘FTO基因的SNP,为今后进一步研究该基因遗传变异奠定基础。本研究以樱桃谷鸭为试验对象,构建DNA池,对第2外显子、第4外显子和第5外显子直接测序,筛选与脂质性状相关的SNP位点。结果表明:FTO基因存在2个SNPs位点突变,在第5外显子发现1个SNP位点突变,另外一个在g.33942位点处,碱基A突变为碱基G,引起天冬氨酸(GAT)变为甘氨酸(GGT),在g.33781位点处,存在碱基T和A的突变(在内含子处,没有引起氨基酸的改变);RNA二级结构的最小自由能由-475.50 kcal/mol变为-477.40 kcal/mol。蛋白质二级结构分析发现,突变前后,α螺旋、β转角、延伸链和自由卷曲数值均有所改变。其中,α螺旋所占比例有所下降,但比重仍为最大,自由卷曲数量由原来的186个减少到185,比例由33.27%减少32.09%。突变前后多态位点导致FTO基因编码的蛋白三级结构也有所改变。FTO基因筛选出的SNP位点,引起RNA二级结构甚至是其编码的蛋白质结构的改变,可能进一步引起功能的改变。     

棕色棉DFR基因的克隆与生物信息学分析

花色素苷是影响花色的主要色素,二氢黄酮醇4-还原酶(DFR)基因是花色素苷生物合成途径的关键酶基因。通过同源克隆策略,以新彩棉6号(XC-6)纤维的RNA以及DNA为模板克隆得到GhDFR基因的CDS全长编码序列及带有内含子的基因组序列,并进行了生物信息学分析。序列分析结果显示,该基因含有6个外显子,5个内含子结构,其cDNA包含一个1 020 bp的开放阅读框,编码355个氨基酸,其氨基酸序列包含具有高度保守性的NADP(H)的结合位点以及底物特异性结合位点。推定的GhDFR蛋白质分子量为39.65 kD,等电点为5.67。该蛋白氨基酸序列同毛果杨、葡萄、天竺葵等物种DFR蛋白显示出较高同源性,而系统进化分析结果表明其与天竺葵、芍药DFR亲缘关系较近。氨基酸序列分析预测表明,GhDFR基因所编码的蛋白不具备信号肽区段,无明显跨膜区域,不属于分泌蛋白,可能为亲水性蛋白,定位于细胞质的可能性最高,其主要二级结构元件为α-螺旋和无规则卷曲。GhDFR属于NADB-Rossmann superfamily。     

FZ6基因及其蛋白的生物信息学分析

目的:对frizzled6(FZ6)基因和Frizzled6(Fz6)蛋白进行生物信息学分析,更多的了解该基因的相关信息,为进一步研究Wnt-Fz信号通路以及FZ基因与神经管发育缺陷相关性研究提供基础。方法:运用Internet上的数据库及程序,对FZ6基因结构、单核苷酸多态性(single nucleotide polymorphisms,SNPs)位点、Fz6蛋白的二级结构、蛋白相互作用网络以及Fz蛋白家族的多重序列比对进行生物信息学分析。结果:FZ6基因染色体定位于8q22.3-q23.1,基因全长33995bp,编码706个氨基酸;编码区存在8个SNPs位点,其中错义SNPs4个;多序列比对结果显示10个Fz蛋白家族成员分为4个亚类,Fz3和Fz6为同一类;Fz6蛋白有2个保守的结构域,蛋白序列羧基端缺少其他Fz蛋白普遍存在的S/T-X-V序列模式;其二级结构以α螺旋和随机卷曲为主。结论:通过对FZ6基因及其蛋白的生物信息学分析获得了其相应的生物学特征,为进一步研究奠定基础。     

牦牛HORMAD1基因的克隆及生物信息学分析

利用分子克隆技术获得了牦牛HORMAD1基因编码区序列,并采用生物信息学方法对该基因及其编码蛋白的基本理化性质、疏水性、信号肽、二级结构等方面进行了预测和分析.结果表明,牦牛HORMAD1基因包含一个长度为1 182 bp的开放阅读框,编码393个氨基酸;其编码蛋白属于亲水性蛋白,无明显的信号肽,含有很多个磷酸化位点.二级结构主要以无规则卷曲和α螺旋为主.HORMAD1基因编码产物氨基酸邻接系统树表明,牦牛HORMAD1与黄牛、马和猪等物种的HORMAD1氨基酸遗传距离较近,具有高度相似性.     

真核生物α-甘露糖苷酶生物信息学分析

α-甘露糖苷酶(α-mannosidase,α-Man)是真核生物蛋白质N-聚糖修饰的关键酶,其对甘露糖残基的修剪过程是糖蛋白N-糖链复杂化的必要步骤,对蛋白质的合成及正确构象的折叠起决定性作用。根据α-Man的功能特异性,其一般被分为糖基水解酶38家族(glycosyl hydrolase 38 family,GH38)、糖基水解酶47家族(glycosyl hydrolase 47 family,GH47)两个家族。利用生物信息学分析GH38家族与GH47家族在进化上的关系和氨基酸序列保守性以及不同物种内质网Ⅰ型甘露糖苷酶(endoplasmic reticulum ManⅠ,ERManⅠ)的理化性质、结构特点、功能特征后发现,GH47家族比GH38家族在进化上更早且保守性更好;α-Man基因在不同物种中长度存在明显差异,物种越高等基因平均长度越长;真核生物ERManⅠ均为亲水性不稳定蛋白质,其氨基酸序列存在跨膜螺旋并含有信号肽,且蛋白质空间构像为桶状,包含Ca~(2+)结合位点。文中对α-Man的生物信息学分析可以为研究α-Man在生命过程中的作用提供重要的信息。     

竹节参鲨烯环氧酶基因的克隆与生物信息学分析

根据已报道的植物鲨烯环氧酶(SE)基因特异性引物克隆竹节参SE基因.结果表明,克隆得到竹节参SE全长为1 632 bp,编码539个氨基酸,命名为PjSE.生物信息学分析指出,PjSE基因的氨基酸序列与人参属植物人参、三七、越南人参的同源性依次为99％、98％和98％.推测PjSE基因定位于线粒体(mTP)、叶绿体(cTP)和分泌途径(SP).PjSE基因存在保守结构域FAD结合位点,含4个跨膜结构域和7个motif结构位点.PjSE蛋白二级结构以无规则卷曲(Random coli)和α-螺旋(Alpha helix)为主要结构元件,延伸链(Extended strand)和β转角(Beta turn)分散于整个蛋白质中,百分比依次占40.82％、37.48％、15.77％、5.94％;该蛋白能折叠形成典型的三维结构.     

Preparation of 6-deoxy-6-fluorocellulose

6-Deoxy-6-fluorocellulose was prepared from cellulose 2,3-diacetate (1) or cellulose 2,3-dibenzoate (2) in various solvents, and was characterized by ¹⁹F and ¹³C NMR measurements. The best product, having ds of 0.95 at C-6 and 0.04 at C-3, was prepared from cellulose 2,3-dibenzoate in nitrobenzene. Other combinations of starting material and solvent gave a lower (≈ 0.8) ds of fluorine at C-6 and higher (≈ 0.12) at C-2 or C-3. Substitution at C-2 was observed when the combination of 1 and 1,4-dioxane, or 2 and chloroform was used. The products substituted at C-2 by fluorine were relatively resistant to acid hydrolysis.     

Facile synthesis of 6-amino-6-deoxycellulose

6-Amino-6-deoxycellulose (4) was synthesized from cellulose by three reaction steps, namely bromination at C-6, displacement of bromine by azide ion, and reduction of the azide group to amino group, in 67% overall yield. The 13C NMR spectrum of compound 4 supports the expected structure for 6-amino-6-deoxycellulose. The degree of substitution of compound 4 was 0.96.     

New 6-butylamino-6-deoxycellulose and 6-deoxy-6-pyridiniumcellulose derivatives with highest regioselectivity and completeness of reaction

This paper investigates the nucleophilic substitution (S(N)) reactions of tosylcellulose with butylamine and pyridine, respectively. The S(N) reactions of tosylcellulose 1 (DS(Total) 2.02; DS(C-6) 1.0) with butylamine carried out at 25, 50, 75 and 100 degrees C in both dimethyl sulfoxide (DMSO) and pure butylamine showed that the regioselectivity of substitution at C-6 of cellulose is temperature dependent: the highest regioselectivity at C-6 can be reached at 25 and 50 degrees C; substitution at C-2 also occurred at 75 and 100 degrees C. The substitution speed in pure butylamine is greater than that in the presence of DMSO. A complete and regioselective substitution at C-6 with a DS of 1.0 was obtained under the conditions of 50 degrees C, 40 h in butylamine. The substitution reactions of 1 with pyridine carried out at 25, 50, 75 and 100 degrees C for 24h in DMSO did not occur. In contrast to this the S(N) reactions done in pure pyridine showed that a temperature- and steric-dependent, regioselective substitution took place at C-6 at temperatures from 25 to 145 degrees C. The highest regioselectivity and completeness at C-6 can be obtained at 100 degrees C for 90 h, whereas at 145 degrees C substitution also occurs at C-2. The results were proved by 1H NMR and 13C NMR spectroscopy.     

Syntheses of stable isotope-labeled 6 beta-hydroxycortisol, 6 beta-hydroxycortisone,and 6 beta-hydroxytestosterone

A method is described for the preparation of two types of multi-labeled 6 beta-hydroxycortisol containing either five deuterium atoms at C-19 methyl and C-1 methylene or four 13C atoms at C-1, C-2, C-4, and C-19 in addition to the five deuterium atoms for use as analytical internal standards for gas chromatography-mass spectrometry (GC-MS). BMD derivatives of [1,1,19,19,19-2H(5)]cortisone and [1,2,4,19-13C(4),1,1,19,19,19-2H(5)]cortisone (cortisone-2H(5)-BMD and cortisone-13C(4),2H(5)-BMD) were first synthesized via indan synthon method starting from optical active 11-oxoindanylpropionic acid and labeled isopropenyl anion ([1,1,3,3,3-2H(5)]- or [1,3-13C(2),1,1,3,3,3-2H(5)]isopropenyl anion). The labeled isopropenyl anion was prepared from commercially available [1,1,1,3,3,3-2H(6)]- or [1,3-13C(2),1,1,1,3,3,3-2H(6)]acetone. Ultraviolet (UV) irradiated autoxidation at C-6 position of 3-ethyl-3,5-dienol ether derivatives of the labeled cortisone-BMDs gave 6 beta-hydroxy-[1,1,19,19,19-2H(5)]cortisone-BMD and 6 beta-hydroxy-[1,2,4,19-13C(4),1,1,19,19,19-2H(5)]cortisone-BMD, respectively, as a mixture of 6 beta- and 6 alpha-epimers in a ratio of 4:1. Separation of 6 beta- and 6 alpha-epimers by thin-layer chromatography (TLC) and subsequent hydrolysis of the BMD group at C-17 gave pure labeled 6 beta-hydroxycortisone. After protecting the keto group at C-3 of the labeled 6 beta-hydroxycortisone-BMD as semicarbazone, reduction of 11-keto group with NaBH(4) and subsequent removal of the C-3 and C-17 protecting groups gave 6beta-hydroxy-[1,1,19,19,19-2H(5)]cortisol (6 beta-hydroxycortisol-2H(5)) and 6 beta-hydroxy-[1,2,4,19-13C(4),1,1,19,19,19-2H(5)]cortisol (6 beta-hydroxycortisol-13C(4),2H(5)), respectively, as a mixture of 6 beta- and 6 alpha-epimers (6 beta:6 alpha=4.4:1). The isotopic compositions of 6 beta-hydroxycortisol-2H(5) and 6 beta-hydroxycortisol-13C(4),2H(5) were 90.9 and 92.1 at.%, respectively. Furthermore, 6 beta-hydroxy-[1 alpha,16,16,17 alpha-2H(4)]testosterone was synthesized by the UV irradiated autoxidation at C-6 position of 3-ethyl-3,5-dienol ether derivative of deuterium-labeled testosterone ([1 alpha,16,16,17 alpha-2H(4)]testosterone) obtained by using catalytic deuteration and hydrogen-deuterium exchange reactions.     

Cytotoxic activity of 6-alkynyl- and 6-alkenylpurines

6-Alkynyl- and 6-alkenylpurines have been screened for cytotoxic activity against a human chronic myelogenous leukemia cell line; K-562 cells using a [(3)H]-thymidine incorporation assay. Most alkynes displayed cytotoxicity comparable to, or better than, the known anticancer drugs 6-mercaptopurine and fludarabine. The 6-alkenylpurines, which are promising plant growth stimulators and 15-lipoxygenase inhibitors, exhibited only low toxicity.     

Synthesis and Properties of 6-Deoxy-6-mercapto-d-glucosamine

6-Deoxy-6-mcrcapto-α-d-glucosamine hydrochloride was synthesized from N-anisylidene-1,3,4-tri-O-acetyl-6-O-tosyl-β-d-glucosamine, and some of its properties were compared with those of α-d-glucosamine hydrochloride.     

Preparation of 6-azafulleroid-6-deoxy-2,3-di-O-myristoylcellulose

6-Azafulleroid-6-deoxy-2,3-di-O-myristoylcellulose (3) was synthesized from 6-azido-6-deoxycellulose (1) by two reaction steps. The myristoylation of compound 1 with myristoyl chloride/pyridine proceeded smoothly to give 6-azido-6-deoxy-2,3-di-O-myristoylcellulose (2) in 97.0% yield. The reaction of compound 2 with fullerene (C₆₀) was carried out by microwave heating to afford compound 3 in high yield. It was found from FT-IR, ¹³C NMR, UV–vis, differential pulse voltammetry (DPV), SEC analyses that compound 3 was the expected C₆₀-containing polymer. Consequently, maximum degree of substitution of C₆₀ (DS_C60) of compound 3 was 0.33.     

Syntheses of (+/-)-methyl 6'alpha-demethyl-6'alpha-cyanoabscisate and (+/-)-methyl 6'alpha-demethyl-6'alpha-methoxycarbonylabscisate

New abscisic acid analogs possessing a cyano or methoxycarbonyl group at the 6'alpha-position of methyl abscisate were synthesized by regioselective hydrocyanation. These compounds had weak activity in the rice second leaf sheath elongation test.