低能氮离子注入固态羧酸钠的质量沉积效应

近年来,低能氮离子束在注入生物诱变、细胞加工和转基因等方面取得了突破性进展［１］,与其他的辐射方法相比,低能离子诱变的主要特点是它不仅具有能量沉积效应,而且具有质量沉积效应［２,３］。质、能量沉积效应双重作用可使物质的原子发生移位和重组,从而会引起分...     

低能氮离子注入固态苯甲酸钠的质量沉积效应

用２５ｋｅＶ氮离子束辐照苯甲酸钠（ＰｈＣＯＯＮａ）引起其分子结构的变化，通过紫外光光度计的分析，得到了其残余紫外活性的剂量效应曲线，另外通过高分辨富里叶红外光谱仪及高灵敏度的茚三酮反应的测定，发现了辐照后的样品中有腈基及α－氨基酸等产物。     

低能氮离子诱发丙酮与重水溶液的反应机理

利用氮气火花放电产生离子,其中的正离子在阴极位降的加速下“注入”到丙酮的重水溶液中,诱发其中的化学反应.利用气相色谱 质谱（GC MS）分析离子注入后的样品,证实有氘代产物（CH3COCH2D）、氘羟基取代产物（CH3COCH2OD）生成,这表明低能N＋诱发重水溶液中的反应主要是由于重水分子分解产生的自由基引起的,其中氘自由基和氘羟基自由基起重要作用;同时,产物中还检测到氘代乙酸（CH3COOD）和氘氨基丙酮（CH3COCH2ND2）,说明反应是在氧化性氛围中进行的,氮离子俘获重水中的氘形成氘氨基可能是氘氨基取代产物生成的主要原因,也是氮“沉积”在溶液中的重要形式.这些结果对初步揭示低能离子诱发水溶液的反应机理具有一定的意义.     

低能离子与腺苷酸组分水溶液作用合成腺苷酸

利用自行设计的实验装置将低能离子引入水溶液以诱发水溶液中的化学反应,模拟原始地球条件研究核苷酸的前生物合成.以低能N＋注入含D 核糖、磷酸二氢铵的腺嘌呤过饱和溶液,用高效液相色谱、核磁共振等方法对反应产物进行分析,证明有5′ 腺苷酸生成.给出了产物的产额时间曲线,并对反应机理作了初步探讨.     

柱前衍生化-HPLC法测定恩施3种富硒蔬菜中硒氨基酸

采用HPLC与ICP-MS间隙联用的方法,以柱前衍生化-HPLC法进行定性定量分析,使用ICP-MS鉴定,建立一种富硒蔬菜中硒氨基酸的分离检测方法。结果表明:所测定的硒代氨基酸在其线性范围内呈现良好的线性关系(R2>0.999)。该方法中硒代蛋氨酸和硒代胱氨酸的检出限分别为0.204 mg/L和0.680 mg/L,加标回收率分别为97.4%和94.0%,RSD分别为2.1%和0.69%。检测恩施富硒蔬菜样品,白菜、萝卜叶和苋菜含有硒代蛋氨酸和硒代胱氨酸。此方法可用于富硒蔬菜中硒代氨基酸的含量检测。     

低能离子注入固态甲酸钠的质能沉积效应

以N~ 、H~ 、Ar 三种离子分别辐照固态甲酸钠样品，经电子顺磁共振（EPR），红外光谱（IR）的检测。结果发现，三种低能离子辐照后的甲酸钠样品中产生了COO~-自由基和亚甲基（－CH_2）．同时，结合茚三酮反应，证明了辐照后的甲酸钠样品中还含有新的基团──氨基（NH_2），并给出了氨基的产生量与注入离子的剂量和能量的相关曲线．     

氨基酸氧化反应的动力学研究

利用紫外吸收光谱谱法研究了α－氨基酸与Ｎ－溴代琥珀酰亚胺（ＮＢＳ）进行氧化反应的动力学，结果表明：反应对ＮＢＳ为一级，对α－氨基酸为正分数级，准一级反应速率常数ｋｏｈａ随（ＯＨ＾－）增加而降低，离子强度及扩散效应对反应无影响，提出了反应的可能机理，导出的速率方程圆满地解释了实验现象，并且计算出了速控步的速率常数、前期平衡常数等动力学参数。     

药物头孢Ⅳ号和氨苄青霉素及其生物合成前体的毛细管区带电泳分离

研究了同分异构体药物头孢Ⅳ号和氨苄青霉素及其目标生物合成前体三肽Ｄ－苯丙氨酸－Ｌ－半胱氨酸－Ｄ－缬氨酸、Ｌ－苯丙氨酸－Ｌ－半胱氨酸－Ｄ－缬氨酸的毛细管区带电泳分离。结果表明，采用含１２ｍｍｏｌ／Ｌ二甲基β－环糊精（ＤＭ－β－ＣＤ）的５０ｍｍｏｌ／ＬＴｒｉｓ－Ｈ３ＰＯ４缓冲溶液（ｐＨ２．３）既可将头孢Ⅳ号和氨苄青霉素分离，又可将Ｄ－苯丙氨酸－Ｌ－半胱氨酸－Ｄ－缬氨酸、Ｌ－苯丙氨酸－Ｌ－半胱氨酸－Ｄ－缬氨酸分离。     

药物头孢Ⅳ号和氨苄青霉素及其生物合成前体的毛细管区带电泳分离

 研究了同分异构体药物头孢Ⅳ号和氨苄青霉素及其目标生物合成前体三肽Ｄ－苯丙氨酸－Ｌ－半胱氨酸－Ｄ－缬氨酸、Ｌ－苯丙氨酸－Ｌ－半胱氨酸－Ｄ－缬氨酸的毛细管区带电泳分离。结果表明，采用含１２ｍｍｏｌ／Ｌ二甲基β－环糊精（ＤＭ－β－ＣＤ）的５０ｍｍｏｌ／ＬＴｒｉｓ－Ｈ３ＰＯ４缓冲溶液（ｐＨ２．３）既可将头孢Ⅳ号和氨苄青霉素分离，又可将Ｄ－苯丙氨酸－Ｌ－半胱氨酸－Ｄ－缬氨酸、Ｌ－苯丙氨酸－Ｌ－半胱氨酸－Ｄ－缬氨酸分离。     

The Synthesis of Cyclic Amino Acids

Several cyclic amino acids (1-4) were synthesized from glycine. Isocyanate ester was prepared as the key intermediate and reacted with dibromoalkanes to afford the target compounds.     

Chemical Synthesis of Proteins Containing 300 Amino Acids

Chemical synthesis of proteins containing up to 300 amino acids may cover 30%-50% of all the proteins encountered in biomedical studies and may provide an alternate approach to the usually used recombinant expression technology, vastly expanding the chemical space of the latter. In the present review article, we tried to survey the recent progresses made for more rapid synthesis of increasingly long peptides and more efficient ligation of multiple peptide segments. The developments of seminal methods by many research groups have greatly contributed to the recent breakthroughs in the successful total synthesis of a number of functionally important proteins, such as oligoubiquitins, bacterial GroEL/ES chaperones, and mirror-image DNA polymerases. Through these studies, a potential bottleneck has also been recognized for the chemical synthesis of large proteins, namely, how to ensure that each peptide segment from a large protein avoids unfavorable aggregation when dissolved in aqueous solution. Many new methods, such as removable backbone modification(RBM) strategy have been developed to overcome this bottleneck, while more studies need to be carried out to develop more effective and less costly methods that ultimately, may lead to fully automatable chemical synthesis of customized proteins of 300 amino acids bearing any artificial designs.     

氟代二苯乙烯氨基酸的合成及性能

以4-碘-L-苯丙氨酸为初始原料,经羧基和氨基的保护得到化合物2;化合物2与4-氟苯乙烯进行Heck反应得化合物3;化合物3脱去保护基得氟代二苯乙烯氨基酸(4,47.4%);其结构经1H NMR,13C NMR,IR和MS(ESI-TOF)确证。光学性质研究结果表明:4的激发、发射波长分别为314 nm和355 nm,斯托克斯位移为41 nm,荧光量子产率为0.22。化合物4在甲醇溶液中存在光致顺反异构现象,反式→顺式结构转变速率常数为0.026 min^-1。     

A Facile Synthesis of N-Phosphoryl Amino Acids Containing Hydroxy Group

three kinds of N-(diisopropyloxyphosphoryl) amino acids containing hydroxyl group were prepared in high yield by using diisopropyl phosphite as the phosphorylating agent, sodium hypochlorite as the chlorinating agent and tetrabutyl ammonium bromide as the phase transfer catalyst in basic aqueous media.     

N-二异丙氧磷酰化氨基酸的合成

以亚磷酸二异丙酯为磷酰化试剂、次氯酸钠为氯代试剂首次对20种常见的α-氨基酸进行了磷酰化.通过添加适量四丁基溴化铵为相转移催化剂,使用过量的亚磷酸二异丙酯以补偿其在强碱环境中的水解,从而提高了反应产率.所得产物经核磁共振谱、红外光谱和质谱鉴定结构并分析总结了该类化合物的谱图特征规律.     

Elucidation of O-Phosphoryl and N-Phosphoryl Amino Acids by Electrospray Ionization Tandem Mass Spectrometry

Mass spectroscopic characteristics of phosphoryl amino acids were studied in detail by positive and negative electrospray ionization mass spectrometry (ESI-MS) in conjunction with tandem mass spectrometry (MS/MS). Besides N-diisopropyloxyphosphoryl amino acids (N-DIPP-AA), O-phospho- and O-diisopropyloxyphosphoryl amino acids (O-DIPP-AA) were studied and compared to N-DIPP-AA. The fragmentation pathways of [M H]^ ,[M Na]^ and [M-H]^- ions of phosphoryl amino acids were summarized. In addition to several similar patterns, each of them showed its characteristic fragmention.     

Enzymatic Synthesis of Dipeptide Derivatives Containing Non-coded Amino Acids in Organic Solvents

ＩｎｔｒｏｄｕｃｔｉｏｎＥｎｚｙｍａｔｉｃｐｅｐｔｉｄｅｓｙｎｔｈｅｓｉｓｈａｓｄｒａｗｎｍｕｃｈａｔｔｅｎ ｔｉｏｎｂｅｃａｕｓｅｏｆｉｔｓａｄｖａｎｔａｇｅｏｆｅｎｚｙｍｅｓｔｅｒｅｏｓｐｅｃｉｆｉｃｉｔｙ ,ｍｉｌｄｒｅａｃｔｉｏｎｃｏｎｄｉｔｉｏｎｓ ,ｍｉｎｉｍｕｍｓｉｄｅ ｃｈａｉｎｐｒｏｔｅｃｔｉｏｎａｎｄａｖｏｉｄａｎｃｅｏｆｒａｃｅｍｉｚａｔｉｏｎ .Ｂｕｔｔｈｅｓｔｒｉｃｔｓｕｂｓｔｒａｔｅｓｐｅｃｉｆｉｃｉｔｙｏｆｔｈｅｅｎｚｙｍｅｓｌｉｍｉｔｓｔｈｅｉｒａｐｐｌｉｃａｔｉｏｎｓ .…     

Extraction Behavior of Amino Acids by Calix[6]arene Carboxylic Acid Derivatives

A series of calixarene carboxylic acid derivatives were synthesized for the extraction of amino acids. A calix[6]arene carboxylic acid derivative showed the highest extractability to the target tryptophan ester. The main driving forcefor the complexation was the interaction between the ammonium cation of the aminoacid and the oxygen atoms of the host molecule. Stripping of amino acids was alsoaccomplished by contacting the organic solution with a fresh acidic solution. Basedon slope and Job method analyses, it was confirmed that the calix[6]arene formsa 1 : 1 complex with the amino acid ester. The structure of the complex between the calix[6]arene and the amino acid was investigated by ¹H-NMR and CD spectra. The calix[6]arene includes a guest molecule in the cavity, and the inclusion induces the asymmetrization of the host molecule. This host compound functions as a novel recognition tool for amino acids.