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.     

手性氨基酸及其衍生物配体在酮不对称氢转移反应中的应用进展

前手性酮的不对称氢转移反应(ATH)是获得手性醇的重要方法.近年来氨基酸及其衍生物在金属Ru,Rh,Ir催化酮的ATH中的应用引起人们关注.就氨基酸、氨基酸酰胺、氨基酸硫代酰胺、氨基酸羟胺酸、氨基酸酰肼、氨基醇及氨基酸羟基酰胺等为配体的金属络合物在ATH中的催化性能进行了综述.     

钯催化的酰胺羰基化反应

酰胺羰基化的发现为氨基酸及其衍生物的合成提供了一个新方法。该合成方法 步骤简洁，只需一步即可从醛、酰胺-氧化碳合成N-酰基氨基酸，而且该反应是原 子经济型反应。与钴催化的酰胺羰基化相比，钯催化的反应条件更为温和，催化效 率也大为提高，对基团有更广普的适应性。简述近所来这一领域的新进展。     

以苯丙氨酸为例刍议芳香族氨基酸的生物合成机理

从磷酸烯醇式丙酮酸和4-磷酸赤藓糖为始探讨了3种芳香族氨基酸合成代谢共享的分支酸合成途径, 并以苯丙氨酸为例从多学科角度讨论分析其合成代谢的独特性。通过多学科角度展示了生物体内不同代谢路径之间的关联及相似性, 旨在展示一种教学新模式,帮助学生建立起跨学科内容的学习及归纳方法。     

Stabilization of β-hairpin structures via inter-strand π-π and hydrogen bond interactions in α-, β-, γ-hybrid peptides

Synthesis and conformational studies of α-, β-, γ-hybrid peptides containing a pyrrole amino acid (Paa, 1) and a furan amino acid (Faa, 2), namely Boc-β-Phe-Faa-d-Pro-Gly-Paa-β-HGly-Faa-OMe (3) and Boc-Paa-β-Phe-Faa-d-Pro-Gly-Paa-β-HGly-Faa-OMe (4), were carried out and they adopt β-hairpin structures stabilized via inter-strand π-π and hydrogen bonding interactions.     

Synthesis and Characterization of Amino Acid Modified Chitooligosaccharides

Amino acid modified chitooligosaccharides were synthesized by the new synthetic route. The chloroacetyl-chitooliogosaccharide intermediates were prepared under a mild condition via a reaction between chitooligosaccharide (COS) and chloroacetic anhydride. The intermediates were subsequently reacted with a variety of amino acids, e.g., glycine, aspartic acid, alanine, arginine, and serine, under a basic condition, yielding amino acid modified COS products. The degree of chloroacetylation was calculated based on new ¹H NMR absorption peaks at 3.80 and 3.94 ppm, corresponding to  NH CO CH₂ Cl and  O CO CH₂ Cl, respectively. The degrees of chloroacetylation determined were 0.40, 0.44, 0.62, and 0.93 when the mole ratios of chloroacetic anhydride to COS were 0.5, 1, 2, and 4, respectively. The chemical structures of the COS derivatives were also determined using ¹H NMR spectroscopy. The biological properties of the derivatives were evaluated. Cytotoxicity of the derivatives was assessed by a direct contact, using L929 cells. An MTT assay was a method of choice to evaluate the efficacy of the derivatives to enhance the proliferation of L929 cells.     

氨基酸卟啉锌配合物对氨基酸酯的分子识别研究(英文)

用紫外可见吸收光谱滴定方法研究了一种新型的苏氨酸卟啉锌配合物(主体)对氨基酸酯(客体)的分子识别.这种锌卟啉可以与氨基酸酯形成 1:1和 1:2的两种加合物.氨基酸酯的氨基首先与氨基酸残基的羧基作用形成 1:1的加合物,然后与锌卟啉的中央锌原子配位形成 1:2的加合物,客体分子与主体分子上的氨基酸残基之间的排斥作用以及主客体之间的色散力作用是主体分子能识别客体分子的另外两种作用。     

Efficient synthesis of a new pipecolic acid analogue with a bicyclic structure

This report describes the synthesis of 2-azabicyclo[2.2.2]octane-1-carboxylic acid, a constrained pipecolic acid analogue. The route gives a very good total yield starting from cheap and readily available compounds and uses very easy reactions.     

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.     

Synthesis of protected α-alkyl lanthionine derivatives

Protected α-alkyl lanthionine derivatives were synthesized in five steps starting from a known phenyloxazoline precursor. This approach involved the synthesis of a family of substituted cyclic sulfamidates and their regioselective opening by nucleophilic attack with a protected cysteine. This efficient multistep strategy affords various α-alkylated lanthionine derivatives in high yields.     

L-谷氨酸、甘氨酸二元、三元体系中铽(Ⅲ)、钙(Ⅱ)的化学形态研究

在模拟生理条件下 (37℃ ,I=0 .1 5mol/ L Na Cl) ,用 p H电位法研究了铽 ( )、钙 ( )与 L-谷氨酸、甘氨酸二元、三元体系。确定了体系存在的物种 ,测定了体系中配合物的稳定常数。讨论了上述二元、三元体系中铽 ( )、钙 ( )的物种分布特点。     

Force-field parametrization of retro-inverso modified residues: Development of torsional and electrostatic parameters

Summary Torsional and the electrostatic parameters for molecular mechanics studies of retro-inverso modified peptides have been developed using quantum mechanical calculations. The resulting parameters have been compared with those calculated for conventional peptides. Rotational profiles, which were obtained spanning the corresponding dihedral angle, were corrected by removing the energy contributions associated to changes in interactions different from torsion under study. For this purpose, the torsional energy associated to each point of the profiles was estimated as the corresponding quantum mechanical energy minus the bonding and nonbonding energy contributions produced by the perturbations that the variation of the spanned dihedral angle causes in the bond distances, bond angles and the other dihedral angles. These energies were calculated using force-field expressions. The corrected profiles were fitted to a three-term Fourier expansion to derive the torsional parameters. Atomic charges for retro-inverso modified residues were derived from the rigorously calculated quantum mechanical electrostatic potential. Furthermore, the reliability of electrostatic models based on geometry-dependent charges and fixed charges has been examined.     

A new constrained proline analogue with an 8-azabicyclo[3.2.1]octane skeleton

A straightforward synthesis of 8-azabicyclo[3.2.1]octane-1-carboxylic acid, a new proline analogue with a bicyclic structure, is described. The procedure makes use of readily available starting materials and involves simple, high-yielding transformations.     

Synthesis of polypeptides from activated urethane derivatives of α‐amino acids

A series of activated urethane‐type derivatives of α‐amino acids were synthesized and applied to polypeptide synthesis. The urethane used herein, N‐(4‐nitrophenoxycarbonyl)‐α‐amino acids 1 , were synthesized by N‐carbamoylation of γ‐benzyl‐L ‐glutamate, β‐benzyl‐L ‐aspartate, L ‐leucine, L ‐phenylalanine, and L ‐proline, with 4‐nitrophenyl chloroformate. When 1 was dissolved in N,N‐dimethylacetamide (DMAc) and heated at 60 °C, it was smoothly converted into the corresponding polypeptides with releasing 4‐nitrophenol and carbon dioxide. Spectroscopic analyses of the obtained polypeptides revealed that they were comparable with the authentic polypeptides synthesized by the ring‐opening polymerizations of amino acid N‐carboxyanhydrides (NCAs). Besides the successful polycondensations of a series of 1 , their polycondensations of 1a and other 1 were also successfully carried out to obtain the corresponding statistic copolypeptides. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 2525–2535, 2008     

Synthesis of protected (2R,3R,4S)-4,7-diamino-2,3-dihydroxyheptanoic acid, a constituent of callipeltins A and D

An efficient synthesis of protected (2R,3R,4S)-4,7-diamino-2,3-dihydroxy heptanoic acid, a constituent of the depsipeptides, callipeltins A and D from l-ascorbic acid is described.     

A compilation of amino acid analyses of proteins

The amino acid analyses of 183 proteins, as residues per 1000 residues, are given. In addition the carbohydrate content and the content of any noncommon amino acids are also given. The sources of all proteins are presented.     

Synthesis of novel proline-thiazole based cyclic hexa- and octapeptides

Novel proline-thiazole based cyclopeptides were produced by cyclooligomerisation of an L-proline thiazole amino acid HCl in the presence of pentafluorophenyl diphenylphosphinate (FDPP) or diphenyl phosphorazidate (DPPA).     

Stereo-regulated synthesis of peptides containing a β-trifluoromethyl-β-amino acid

For the chemical conversions of a β-trifluoromethyl-β-amino acid ((S)-4,4,4-trifluoro-3-aminobutyric acid, 1), such as the N-terminus protection with benzyloxycarbonyl or tert-butoxycarbonyl group, the C-terminus protection with benzyl or tert-butyl group, and peptide elongation at the both termini, highly practical protocols were established. Through these conversions, the stereochemistry of 1 and/or its condensation counterpart was maintained. Because the protocols developed here are indispensable for the application of 1 in peptide engineering, they would expand the utility of 1 and its derivatives.     

壳聚糖-氨基酸体系中碳酸钙模拟生物矿化的研究

本文选取壳聚糖与氨基酸作为碳酸钙模拟生物矿化的有机基质,研究并比较了侧链带不同电荷的氨基酸对碳酸钙生物矿化的调制作用,发现侧链带负电荷的酸性氨基酸能改变壳聚糖体系中原有的晶种模板,使能量比较高的球霰石型碳酸钙得以生成,而单纯的壳聚糖体系中只能得到方解石型碳酸钙;在形貌上则改变了球霰石型碳酸钙原有的球状堆积,出现了两头小、中间大椭球状的特殊形貌。