Genetic Code: Emergence of a Symmetrical Pattern

The triplets of nucleotides which apparently specify the detailed structure of proteins fall into a regular pattern: the 64 combinations of four nucleotides taken three at a time, are resolved into 32 pairs. The second member of each pair is identical with the first, except that in one position a purine is replaced by the other purine or a pyrimidine by the other pyrimidine. Almost all of the reported triplets fit into this pattern, and from it one can predict which amino acids will be found to correspond to the remaining 19 unidentified triplets. This pattern accounts for several of the observations concerning regularities in the data, partially determines the order of the nucleotides in each triplet, and suggests a structural basis for transfer RNA specificity.     

氨基酸对蛋白质翻译起始因子的调控

氨基酸既是蛋白质合成的底物又是细胞内信号传导通路的调节物。综述了蛋白质翻译起始过程、氨基酸在翻译起始Met-tRNAi结合阶段和mRNA结合阶段的调节及氨基酸调节蛋白翻译起始的信号传导机制。     

Immunoglobulin structure: variation in amino acid sequence and length of human lambda light chains

Variation and conservation in the primary structure of human lambda light chains is revealed by complete amino acid sequence of three Bence Jones proteins. These proteins differ in amino acid sequence in from 38 to 48 positions; they are of unequal length in the amino-terminal half of the chain but have identical sequence in the last 105 amino acids.     

多肽和蛋白质的人工合成评述

多肽和蛋白质的人工合成,就是多个氨基酸在一定的条件下通过肽键形成多肽链。氨基酸是合成多肽和蛋白质的原料。在合成前各个氨基酸都必须经过基团保护、氨基和羧基的活化处理,然后经接肽,去除保护基,最后形成多肽链。本文对目前国内外常用的液相合成法和固相合成法的原理和步骤进行了简要的评述。     

猪T细胞受体β链基因的克隆及生物信息学分析

以GenBank上登载的猪的T细胞受体β(pTCR-β)基因为参考序列,用RT-PCR法从猪的外周血淋巴细胞中克隆了TCR-β链基因,并进行生物信息学分析.结果表明:pTCR-β基因含有一个完整的开放阅读框架(ORF),大小为849bp,编码283个氨基酸,且含有一段27个氨基酸的信号肽序列,与参考序列相比,在核苷酸序列上的同源性为80.4%,在氨基酸序列上的同源性为70.3%;生物信息学结构预测发现2个结构域,一个为IG结构域,由第32-138位共107个氨基酸残基组成;另一个为IG-LIKE结构域,由第164-211位共48个氨基酸残基组成.     

Nucleotide sequence of the transforming gene of avian myeloblastosis virus

Avian myeloblastosis virus is defective in reproductive capacity, requiring a helper virus to provide the viral proteins essential for synthesis of new infectious virus. This virus arose by recombination of the nondefective helper virus and host cellular sequences present within the normal avian genome. These latter sequences are essential for leukemogenic activity. The complete nucleotide sequence of this region is reported. Within the acquired cellular sequences there is an open reading frame of 795 nucleotides starting with the initiation codon ATG (adenine, thymine, guanine) and terminating with the triplet TAG. This open reading frame could code for the putative transforming protein of 265 amino acids with a molecular weight of approximately 30,000.     

苹果新梢离体不定根形成期间某些生理变化的研究

以苹果离体培养的新梢为试材,研究了不定根发生和发育期间淀粉、可溶性糖、蛋白质、游离氨基醚含量和过氧化物酶活性的变化规律.在根原基形成时,淀粉大量消耗,蛋白质和游离氨基酸含量增加,过氧化物酶活性增强;而在根原基形成后根的生长过程中,淀粉含量回升,蛋白质、游离氨基醚含量和过氧化物酶活性下降.在根原基形成和根的生长过程中,可溶性糖含量略有增加.     

Evidence for dispensable sequences inserted into a nucleotide fold

Previous experimental results along with the structural modeling presented indicate that a nucleotide fold starts in the amino-terminal part of Escherichia coli isoleucyl-transfer RNA synthetase, a single chain polypeptide of 939 amino acids. Internal deletions were created in the region of the nucleotide fold. A set of deletions that collectively span 145 contiguous amino acids yielded active enzymes. Further extensions of the deletions yielded inactive or unstable proteins. The three-dimensional structure of an evidently homologous protein suggests that the active deletions lack portions of a segment that connects two parts of the nucleotide fold. Therefore, the results imply that removal of major sections of the polypeptide that connects these two parts of the fold does not result in major perturbation of the nucleotide binding site.     

蕨麻猪白细胞抗原Ⅰ类分子3基因的克隆和序列分析

参照GenBank上登录的猪SLA-3基因序列(GenBank登录号:AF464010)设计1对引物,从经ConA刺激的蕨麻猪外周血液淋巴细胞中提取RNA,进行克隆、测序以及同源性分析和蛋白结构预测分析.结果表明:克隆的蕨麻猪SLA-3基因大小为1 086 bp,含一个完整的开放阅读框,编码361个氨基酸,还含有一段21个氨基酸的信号肽序列;核苷酸序列与GenBank上登录的SLA-3参考序列的同源性为93.1%;与牛、绵羊、山羊的同源性较高,而与鸡的同源性最低.蛋白分子结构预测表明,猪SLA-3基因编码的蛋白分子是由胞外区(303个氨基酸)、跨膜区(23个氨基酸)和胞内区(35个氨基酸)组成的一种跨膜蛋白.     

60Co辐射诱变姬松茸突变株J3的氨基酸分析与比较研究

测定并比较了~(60)Co辐射诱变姬松茸突变株J_3子实体与姬松茸原菌株子实体的氨基酸含量。结果表明,姬松茸突变株J_3子实体富含8种人体必需氨基酸、支链氨基酸、谷氨酸、赖氨酸和儿童氨基酸,分别比姬松茸原菌株子实体高66.67％、52.44％、77.36％、59.58％和71.57％。姬松茸突变株J_3子实体中支链氨基酸与芳香氨基酸比值也高于姬松茸原菌株及2种食用蛋白质和4种农产品。     

含支链氨基酸饮料对高温环境下小鼠体能恢复的影响

合支链氨基酸饮料是一种体能型特需饮料，能迅速恢复高温条件下机体体能的损失。本研究以BALB／C近交系小鼠作为实验动物模型，人工模拟30℃的高温条件，将小鼠间断地暴露于高温中，在高温处理期间，给小鼠分别喂饮含支链氨基酸饮料和雪碧对照饮料，然后进行体能各项指标的测定。结果表明：饮用含支链氨基酸饮料组小鼠体质量增加显著，运动能力增强，运动后血糖含量高，血乳酸含量低，同时其耐热、抗疲劳、耐缺氧能力显著增强。     

Cloning and Expression Profile of Deoxyhypusine Snyhtase Gene and Deoxyhypusine Hydroxylase Gene in Silkworm, Bombyx mori

Deoxyhypusine snyhtase （DHS） and deoxyhypusine hydroxylase （DOHH） are the two enzymes that catalyze the synthesis of hypusine within eukaryotic initiation factor 5A （eIF5A）. Synthesis of hypusine is essential for the function of eIF5A in eukaryotic cell proliferation and survival. Here we described the cloning and expression of two full-length cDNAs, encoding respectively DHS-like protein and DOHH-like protein from Bombyx mori by using the methods of bioinformatics, RACE, and RT-PCR technology, named as BmDHS and BmDOHH. Sequencing results indicate that they are 1 311 and 1 874 bp in length including complete open reading frame （ORF） 1 116 and 915 bp, which encode 371 amino acids （molecular weight is about 41.11 kD and isoelectric point is 5.84） and 304 amino acids （molecular weight is about 34.30 kD and isoelectric point is 4.86）, respectively. BmDHS contains only 1 exon, and BmDOHH contains 4 exons and 3 introns. The deduced amino acid sequence of BmDHS contains a deoxyhypusine synthase domain from 47 to 361 amino acid residues, and the deduced amino acid sequence of BmDOHH contains 6 E-Z type HEAT repeat domains （23-52, 54-83, 87-116, 177-206, 208-237, and 241- 270）. Compared to DHS and DOHH amino acid sequences from other species, such as Homo sapiens and Drosophila melanogaster, both silkworm DHS protein and DOHH protein have more than 55% identity. The conservative regions are very similar with each other. The phylogenetic tree analysis indicated that not only DHS but also DOHH from different species has genus-specific features. The expressions of BmDHS and BmDOHH are no tissue and stage specific in our tested samples.     

~(60)Co诱变姬松茸突变株J_3与原菌株J_1的比较研究

通过姬松茸60Co辐射诱变育种获得突变株J3,测定并比较研究了60Co辐射诱变姬松茸突变株J3与原菌株J1 子实体的产质量,氨基酸、微量元素和重金属镉含量的变化。结果表明,突变株J3子实体的产量、儿童氨基酸、鲜味氨基酸、甜味氨基酸、必需氨基酸、支链氨基酸和芳香族氨基酸以及微量元素Fe、Mn、Ti和Mo含量均高于原菌株J1;而重金属镉(Cd)含量仅为原菌株J1的36．19％,克服了姬松茸镉含量超标的问题,具有一定的开发价值。     

PHYSIOLOGY OF THE AMINO ACIDS

We have followed the amino acids from their entrance into the alimentary tract in the form of food proteins through the successive steps of digestion, absorption into the blood stream and passage from the blood stream into the tissues, where they are concentrated by some unknown mechanism to many times their concentration in the blood plasma. We have seen something of the way in which certain of the amino acids can be transformed into one another in the body or synthesized from ammonia and keto acids. However, we have had to admit that our bodies can form in such ways only about half of the different amino acids that are required, and that the other half must be made for us by plants, bacteria or other organisms which have greater synthetic powers than we. And finally we have seen something of the manifold fates of the amino acids after they have entered our tissues; how they may be destroyed and their nitrogenous parts turned into urea in the liver before it is possible to put them to their more specialized uses, how their carbon fractions can be used to form glucose, how they may sacrifice themselves to protect us from toxic products, how they can serve as source material for certain vitamins, hormones and other compounds with physiological functions still to be identified, and how finally those amino acids which are not deflected to these various fates may enter into the proteins of the tissues and become for a time parts of our living structures.     

马铃薯X病毒黑龙江分离物外壳蛋白基因克隆与序列分析

马铃薯X病毒(Potato virus X,PVX)是重要的马铃薯病毒之一,几乎分布于全国所有马铃薯种植区域,严重影响马铃薯的产量和品质。对其建立RT-PCR分子检测体系以及对其外壳蛋白(CP)基因进行序列分析尤为重要。根据已报道的PVX的核苷酸序列设计合成1对引物,以带毒植株总RNA为模板,应用RT-PCR方法,克隆了PVX黑龙江分离物(P2)全长CP基因序列。序列分析表明:P2CP基因全长711 bp,编码237个氨基酸残基,与GenBank中17个不同分离物的CP核苷酸序列同源性为75.5%~96.3%,氨基酸序列同源性为89.4%~99.2%。依据PVXCP氨基酸序列建立系统进化树,将PVX不同分离物划分为两大类群,P2与PVX中国分离物亲缘关系较近,同属于类型Ⅱ,表现一定的地域相关性。同时,应用该RT-PCR分子检测体系进行马铃薯样品检测。     

槟榔碱合成前体物质的空间分布及槟榔碱合成通路解析

为探究槟榔中的生物活性成分,本研究以不同组织的槟榔为材料,利用高效液相色谱?质谱联用技术进行了非靶向代谢组学检测,经过定性分析,共获得了158个代谢物（包括氨基酸、脂质、核苷酸、生物碱和类黄酮等物质）,首次在槟榔中发现槟榔次碱己糖苷的存在,并对氨基酸和生物碱进行了相对定量,发现芳香族氨基酸和支链氨基酸主要分布在种子中;烟酸衍生物在叶片中含量较高,槟榔次碱己糖苷和去甲基槟榔碱在外果皮中含量较高,其余生物碱均显示出在果实中尤其是种子中有较多的积累。基于烟酸、葫芦巴碱和槟榔碱的结构相似性,推测槟榔碱的合成通路是以天冬氨酸为起点,以烟酸、葫芦巴碱为基本骨架进行合成的。     

烟台沿海4种常见海藻的氨基酸分析及营养评价

用高效液相色谱仪测定了烟台沿海4种常见海藻中各种氨基酸的组成,并对其进行营养评价。结果表明:4种海藻样品经酸水解处理,均含有16种氨基酸,包括7种人类必需的氨基酸,2种半必需氨基酸和其他7种非必需氨基酸;各种必需氨基酸的配比合理,除叉枝藻外,其他3种海藻的E/N和E/T值与WHO/FAO提出的E/N约为60%、E/T约为40%的蛋白质参考模式相接近;萱藻和叉枝藻总氨基酸含量比较高,分别为11.30%和10.32%;此外,4种海藻中普遍含有多种药效氨基酸。说明4种海藻具有丰富的营养价值和良好的药用价值,值得大力开发利用。     

珊瑚藻藻红蛋白β亚基脱辅基蛋白基因克隆与序列分析

首次报道珊瑚藻R-藻红蛋白β亚基基因的全序列.测定的基因序列长为983个碱基,包括β亚基起始密码子上游的10个碱基、β亚基编码区的534个碱基(编码177个氨基酸)、101个碱基的间隔区以及α亚基编码区近5′端的338个碱基(编码112个氨基酸).对其序列在核酸和氨基酸水平上的同源性与已知基因序列的9种红藻作了比较分析,认为β亚基氨基酸序列在红藻分类上具有重要意义.     

Regulation of chromosome replication in Bacillus subtilis: marker frequency analysis after amino acid starvation

Marker frequency analysis of DNA isolated from amino acid-starved Bacillus subtilis cells shows that most chromosomes have not completed replication to the terminus. This finding agrees with earlier results concerning replication after amino acid starvation in this organism. The results are not compatible with regulation of chromosome replication at the initiation step only, and they suggest that a second regulatory circuit controls replication under conditions of amino acid starvation.