等渗水分和盐胁迫对水稻幼苗叶片氨同化的影响

在盐（NaCl）胁迫和等渗的聚乙二醇（polyethylene glycol，PEG）6000引起的水分胁迫下，检测了水稻叶片NH4^＋同化酶及其相关参数。结果表明，两种胁迫均对水稻叶片NH4^＋的同化产生了显著的影响。与PEC-6000相比，在等渗条件下，NaCl更显著的抑制了谷氨酰胺合成酶（GS）的活性，造成叶片中NH4^＋的积累水平更高，与盐胁迫一样，NH4^＋的积累同样也诱导了水分胁迫下依赖于NADH的谷氨酸脱氢酶（NADH—GDH）水平的上升，但与盐胁迫相比，上升幅度较小。     

外源水杨酸对水稻(Oryza sativa L.)幼苗根的NaCl胁迫缓解效应

为研究25mg／L外源水杨酸对0，50，100mmol／L NaCl处理下水稻幼苗根的胁迫缓解效应，测定了根组织内脯氨酸含量、可溶性糖含量、氨同化关键酶活性等相关指标．结果表明外源水杨酸可使组织内脯氨酸含量显著降低至与正常对照相当水平，而可溶性糖含量升高，说明外源水杨酸存在时可溶性糖作为主要渗透胁迫调节物并对盐胁迫适当缓解，表现在幼苗根谷氨酰胺合成酶及依赖于NADH的谷氨酸脱氢酶的活性上升20％左右、可溶性蛋白质含量的提高，氮同化加强而对盐胁迫有一定的抗性．对50mmol／L NaCl胁迫处理的材料缓解效应较显著．     

合成聚肽嵌段共聚物PHEG-PBLG结构的核磁共振分析

通过L-谷氨酸苄酯和三光气反应制备谷氨酸苄酯的N-羧酸酐,以聚羟乙谷氨酸酰胺为大分子引发剂,投入不同配比的单体/引发剂（A/I）,共聚得到两亲性嵌段共聚物聚羟乙谷氨酰胺-聚谷氨酸苄酯（PHEG-PBLG）;通过核磁共振技术分析表征该合成聚肽的结构组成、分子量范围及螺旋结构;通过体外酶解实验研究了共聚物的降解情况. 研究结果表明：该合成聚肽化合物为两亲性嵌段聚合物：当聚合物中亲水链段PHEG分子量为9000,A/I为75∶1, 100∶1, 150∶1, 200∶1时,相应的共聚物的分子量分别为：1.27×10⁴,1.75×10⁴, 1.9×10⁴, 3.60×10⁴;该合成聚肽含有α-螺旋结构, 随着TFA的加入,该聚肽的结构由α-旋构象转化为随机盘绕构象.     

3-Substituted Anilines as Scaffolds for the Construction of Glutamine Synthetase and DXP-Reductoisomerase Inhibitors

Access to a series of truncated ATP analogs, as potential anti-tuberculosis agents, has been explored via alkylation and acylation of 3-aminophenol, whereas chloroacetylation, using chloroacetyl chloride, and subsequent Arbuzov phosphonation of a series of 3-substituted anilines have afforded a series of phosphonate derivatives as potential antimalarial agents.     

Glucose and glutamine metabolism of a murine B-lymphocyte hybridoma grown in batch culture

The energy metabolism of a mammalian cell line grown in vitro was analyzed by substrate consumption rates and metabolic flux measurements. The data allowed the determination of the relative importance of the pathways of glucose and glutamine metabolism to the energy requirements of the cell. Changes in the substrate concentrations during culture contributed to the changing catalytic activities of key enzymes, which were determined.

Fragmentation reactions of protonated peptides containing glutamine or glutamic acid

A variety of protonated dipeptides and tripeptides containing glutamic acid or glutamine were prepared by electrospray ionization or by fast atom bombardment ionization and their fragmentation pathways elucidated using metastable ion studies, energy-resolved mass spectrometry and triple-stage mass spectrometry (MS(3)) experiments. Additional mechanistic information was obtained by exchanging the labile hydrogens for deuterium. Protonated H-Gln-Gly-OH fragments by loss of NH(3) and loss of H(2)O in metastable ion fragmentation; under collision-induced dissociation (CID) conditions loss of H-Gly-OH + CO from the [MH - NH(3)](+) ion forms the base peak C(4)H(6)NO(+) (m/z 84). Protonated dipeptides with an alpha-linkage, H-Glu-Xxx-OH, are characterized by elimination of H(2)O and by elimination of H-Xxx-OH plus CO to form the glutamic acid immonium ion of m/z 102. By contrast, protonated dipeptides with a gamma-linkage, H-Glu(Xxx-OH)-OH, do not show elimination of H(2)O or formation of m/z 102 but rather show elimination of NH(3), particularly in metastable ion fragmentation, and elimination of H-Xxx-OH to form m/z 130. Both the alpha- and gamma-dipeptides show formation of [H-Xxx-OH]H(+), with this reaction channel increasing in importance as the proton affinity (PA) of H-Xxx-OH increases. The characteristic loss of H(2)O and formation of m/z 102 are observed for the protonated alpha-tripeptide H-Glu-Gly-Phe-OH whereas the protonated gamma-tripeptide H-Glu(Gly-Gly-OH)-OH shows loss of NH(3) and formation of m/z 130 as observed for dipeptides with the gamma-linkage. Both tripeptides show abundant formation of the y(2)' ion under CID conditions, presumably because a stable anhydride neutral structure can be formed. Under metastable ion conditions protonated dipeptides of structure H-Xxx-Glu-OH show abundant elimination of H(2)O whereas those of structure H-Xxx-Gln-OH show abundant elimination of NH(3). The importance of these reaction channels is much reduced under CID conditions, the major fragmentation mode being cleavage of the amide bond to form either the a(1) ion or the y(1)' ion. Particularly when Xxx = Gly, under CID conditions the initial loss of NH(3) from the glutamine containing dipeptide is followed by elimination of a second NH(3) while the initial loss of H(2)O from the glutamic acid dipeptide is followed by elimination of NH(3). Isotopic labelling shows that predominantly labile hydrogens are lost in both steps. Although both [H-Gly-Glu-Gly-OH]H(+) and [H-Gly-Gln-Gly-OH]H(+) fragment mainly to form b(2) and a(2) ions, the latter also shows elimination of NH(3) plus a glycine residue and formation of protonated glycinamide. Isotopic labelling shows extensive mixing of labile and carbon-bonded hydrogens in the formation of protonated glycinamide.     

叠氮法合成谷氨酰胺类化合物及其抗肿瘤活性

研究发现抗癌酮（Antineoplaston A10）降解物中谷氨酰胺与异谷氨酰胺类衍生物显示出抗肿瘤少性。为此，设计并合成了一系列苯乙酰谷氨酰胺类化合物供抗肿瘤活性筛选，采用合成酰基叠氮化合物，再与胺类于低湿下反应生成酰胺类目标化合物，该方法反应条件温和，收率好，而且手性中心不发生消旋化，所合成化合物结构经IR、^1HNMR、MS及元素分析方法鉴定。对所合成目标化合物做抗肿瘤活性评价，采用MTT法对L1210细胞进行了测试，初步结果显示有一定的抑制肿瘤细胞存活的作用。     

牛体外受精卵发育培养条件的研究

将采自屠宰母牛卵巢的未成熟卵子在含有促进性腺激素和胎牛血清的TCM199培养基内培养成熟后,使用以钙离子载体Ionophore A23187诱导获能的牛精子进行授精处理.在受精卵发育用培养基中添加了谷氨酰胺,并以此与无添对照进行了对比,探索了培养基内谷氨酰胺的存在与否对胚胎发育的影响.另外,在发育用培养基内还分别添加了胎牛血清(FCS),阉牛血清(NSS)以及发情母牛血清(OCS)以观察其培养效果,结果表明,谷氨酰胺对胚胎的发育有极大的促进作用,添加谷氨酰胺的处理组与对照组中发育为桑椹胚、囊胚的胚胎比例分别为23.4%和6.6%,具有极显著的整异.而在含有FCS、NSS和OCS的TCM199培养基内培养的卵子中分别有81.4%,70.7%和82.9%发育为二细胞期胚胎,将胚胎继续培养至授精后第8天时,三个处理组中发育为桑椹胚、囊胚的胚胎比例分别为30.0%,40.2%和47.1%,以OCS的培养效果为最佳.本研究的结果证明,谷氨酰胺和发情母牛血清对牛体外受精卵的体外发育具有良好的促进作用.     

The Structure of Ammonium,D,L—Tartrate

1 INTRODUCTION The enantiomers separated by a co- crystallization method using an appropriate chiral as separating reagent has attracted many attentions in the past years[1]. Recently we are interested in enantiomeric discrimination by chiral amino acid. When racemic D,L-tartaric acid was tried to be separated by the L-glutamine in a hot aqueous solution, the well shaped crystals were obtained. The determination of melting point (220℃) and density (1.66 g穋m－3) showed it is…     

Targeting Glutaminase by Natural Compounds: Structure-Based Virtual Screening and Molecular Dynamics Simulation Approach to Suppress Cancer Progression

Cancer cells change their glucose and glutamine (GLU) metabolism to obtain the energy required to continue growing. Glutaminase (GLS) plays a crucial role in promoting cell metabolism for cancer cell growth; targeting GLU metabolism by inhibiting GLS has attracted interest as a potential cancer management strategy. Herein, we employed a sequential screening of traditional Chinese medicine (TCM) database followed by drug-likeness and molecular dynamics simulations against the active site of GLS. We report 12 potent compounds after screening the TCM database against GLS, followed by a drug-likeness filter with Lipinski and Veber rule criteria. Among them, ZINC03978829 and ZINC32296657 were found to have higher binding energy (BE) values than the control compound 6-Diazo-5-Oxo-L-Norleucine, with BEs of −9.3 and −9.7 kcal/mol, respectively, compared to the BE of 6-Diazo-5-Oxo-L-Norleucine (−4.7 kcal/mol) with GLS. Molecular dynamics simulations were used to evaluate the results further, and a 100 ns MD simulation revealed that the hits form stable complexes with GLS and formed 2–5 hydrogen bond interactions. This study indicates that these hits might be employed as GLS inhibitors in the battle against cancer. However, more laboratory tests are a prerequisite to optimize them as GLS inhibitors.