丝组二肽对DNA切割作用的QM-MM研究

运用QM-MM方法对丝组二肽切割DNA作用的机理进行了研究．通过计算得到了丝组二肽与DNA形成多氢键作用的有效分子识别模型及相关分子结构参数,从理论上解释了丝组二肽与DNA通过形成五配位磷中间体而使磷酸二酯键发生水解,从而使得DNA被切断的作用机理。     

Synthesis of Phosphopeptides with Enzymatic Protecting Group

Reversible protein phosphorylation is widely recognized as an important mechanism for the regulation of many cellular processe^[1]. For the study of the roles of the phosphoproteins in biological processes, structurally well-defined compounds are often needed, which contain the characteristic structural units of the parent biomacromolecules, i.e. the linkage regions between the peptide chain and phosphoric acid esters.     

Synthesis of Nα, Nε-Bis(O-deoxythymin-3'-ylO-isopropyl phosphoryl) Lysine Methyl Ester

The report of Lienhard and Secemski¹ on the potent inhibition of adenylate kinase by the dinucleoside analogue of adenosine, P1, P5-di(adenosine-5')pentaphosphate (Ap5A), stimulated our synthesis of N^α, N^ε-bis(O-deoxythymin-3'yl O-isopropyl phosphoryl) lysine methyl ester (BTPL) as a potential inhibitor of the metabolic pathway concerned with the biosynthesis of DNA-thymine. To our knowledge, it's the first example of lysine linked two nucleotides through P-N bond.     

日球磁参数与太阳活动

本文从统计分析的角度讨论了太阳活动对日球参数的影响。 得到的重要结果是:包括磁场在内的一些参数的组合,即磁参数,是衡量、区分或识别不同太阳现象对日球影响的特征物理量。其中磁压热压比μ_p既是衡量太阳黑子活动,尤其是区分强耀斑活动影响,也是识别太阳活动极大年后,冕洞稳定高速流区在太阳活动上升及极大年的前兆的特征物理量。磁声波速C_as在太阳活动周不同位相,具有相当稳定的双峰日面经度分布,高磁声波速是太阳活动上升及极大年强磁场流区和极大年后稳定高速流区的共同特征。其他磁参数,如阿尔文波速C_a,磁压动能密度比μ_k以及总压力动能密度比π_k^*也都在一定程度上反映上述特性。     

Neutron Diffraction Study on Structure of α－LiIO_3 Single Crystal under DC Voltage

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Studies on the Reaction of Salicylic Acid with Dialkyl Phosphite by Electrospray Ionization Mass Spectrometry and 31p NMR

The Atherton-Todd reaction has been extensively applied to the synthesis of phosphates and phosphoroami dates. [1] Zeng et al. [2] suggested that under Atheron-Todd reaction conditions, dialkyl phosphites are transformed into diakyl phosphorochloridates.     

Analysis of Hydrolysis Reaction of N-Phosphorylphenylalanine by HPLC-ESI-MS/MS

Hydrolysis procedure of N-diisopropyloxyphosphoryl phenylalanine (DIPP-Phe) has been studied by HPLCESI-MS. The hydrolysis products and intermediate were identified by HPLC-ESI-MS/MS. The results showed that (HO)(i-PrO)P(O)Phe was intermediate in the hydrolysis process.     

一锅法合成O-(3-薯蓣甙元) -O′-[5′-(3′-叠氮-3′-脱氧胸苷)]-氢亚磷酸酯

3′-叠氮-3′-脱氧胸苷(1)(AZT结构见Scheme 1)是FDA批准的第一个用于治疗HIV感染的双脱氧核苷类药物, 已在临床上得到了广泛的使用[1]. 但作为一种有效的逆转录酶抑制剂, 该药物在临床使用过程中面临许多亟待解决的问题. 例如, 长期使用会引起核苷第一步磷酰化所需胸苷激酶的活性降低, 从而引起病毒对药物的耐受性, 降低治疗效果. 另外, 长期使用该药物会产生脊髓抑制的副作用, 如贫血和中性粒细胞减少, 因而使治疗不能持续[2,3].     

Characterization of novel nucleoside analogs by electrospray ionization mass spectra

In this paper, we synthesized a novel nucleoside analog by coupling thymine with dimethyl dicarboxylate biphenyl (DDB). The structure of the target compound was determined using 1H nuclear magnetic resonance (NMR) and electrospray ionization tandem mass spectrometry (ESI-MS/MS). The fragmentation pathways were studied in details through ESI-MS/MS. By comparing with unsubstituted nucleosides, such as AZT, MCI, d4T and DDI, it was found that the nucleoside analog coupled with DDB would not yield the daughter ions corresponding to the fragments of the nucleoside base and arabinofuranose analogs, but would lose a neutral molecule HF and DDB easily. However, the unsubstituted nucleosides could lightly yield the fragment ions of the nucleoside base and sugar ring. Hence, electrospray ionization mass spectrometry combined with tandem mass spectrometry (MS/MS) provides a convenient method to recognize the substituted and unsubstituted nucleosides.     

O-磷酸-L-丝氨酸及其衍生物的合成

介绍具有重要药理和生物活性的O-磷酸-L-丝氨酸及衍生物的合成. O-磷酸-L-丝氨酸通过部分水解的三氯氧磷与L-丝氨酸反应制得, 并培养得到了其晶体, 利用X射线衍射方法测定了它的晶体结构; 进而合成了O-磷酸-L-丝氨酸钙盐和O-磷酸-L-丝氨酸单(或双)二异丙胺盐. 产物经核磁共振、红外光谱和质谱进行了结构表征.