腺嘌呤和质子化腺嘌呤的结构和振动光谱

用密度泛函方法B3LYP/aug-cc-pVTZ分析了腺嘌呤和质子化腺嘌呤的低能稳定异构体的结构和振动光谱. 结果发现, 对于中性腺嘌呤分子, 腺嘌呤的异构体N9H比N7H的能量低32.76 kJ·mol-1(在极化连续模型下为6.28 kJ·mol-1). 基于标度量子力场方法所得到的势能分布, 对异构体N9H的部分振动基频重新进行了归属. 在极化连续模型下, 质子化腺嘌呤分子有5种低能稳定构型, 其中N1位质子化的9-位氢腺嘌呤最为稳定. 基于振动模式分析, 对这种最稳定构型的振动基频进行了归属, 并对腺嘌呤在pH=1的高氯酸溶液中的实验拉曼光谱进行了指认.     

Theoretical study of water-assisted hydrolytic deamination mechanism of adenine

The water-assisted hydrolytic deamination mechanism of adenine was studied using density functional method at B3LYP/6-311G(d,p) level. Intrinsic reaction coordinate (IRC) calculations were performed on the transition states to verify whether it is the real transition states that connect the corresponding intermediates. Single-point calculations were carried out on the previous optimized geometries obtained during IRC calculations. The activation energies have also been calculated using G3MP2//B3LYP/6-311G(d,p) method. The water molecules attack the adenine and a tetrahedral intermediate forms. Then, two different intermediates have been obtained through different bond rotations. In pathway a, the second water molecule takes part in the formation of transition state and acts as a bridge to transfer hydrogen atom, while in pathway b, the second water molecule does not involve in the creation of transition state and only acts as a medium. The energy barriers are 23.40 and 37.17 kcal/mol for pathways a and b, respectively. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

胶束毛细管电动色谱法用于DNA碱基腺嘌呤和嘌呤类抗癌药物的研究

腺嘌呤（ADE）是存在于自然界的DNA碱基之一,8-羟基嘌呤（8-HP）是DNA中氧化损伤产物,6-巯基嘌呤（6-MCP）和8-氮杂鸟嘌呤（8-AZN）都属于核酸代谢拮抗药物,该药主要用于治疗急性白血病,对慢性颗粒细胞白血病及其它多种肿瘤也较有效,能在一个体系里同时检测正常DNA碱基、DNA中氧化损伤产物和抑制DNA损伤的抗癌药物,     

A rapid and simple chemical method for the preparation of Ag colloids for surface-enhanced Raman spectroscopy using the Ag mirror reaction

Colloidal silver (Ag) nanoparticles (AgNP) have been widely used for surface-enhanced Raman spectroscopy (SERS) applications. We report a simple, rapid and effective method to prepare AgNP colloids for SERS using the classic organic chemistry Ag mirror reaction with Tollens’ reagent. The AgNP colloid prepared with this process was characterized using SEM, and the reaction conditions further optimized using SERS measurements. It was found that Ag mirror reaction conditions that included 20 mM AgNO₃, 5 min reaction time, and 0.5 M glucose produced AgNP colloids with an average size of 319.1 nm (s.d ± 128.1). These AgNP colloids exhibited a significant SERS response when adenine was used as the reporter molecule. The usefulness of these new AgNP colloids was demonstrated by detecting the nucleotides adenosine 5′-mono-phosphate (AMP), guanosine 5′-monophosphate (GMP), cytidine 5′-monophosphate (CMP), and uridine 5′-monophosphate (UMP). A detection limit of 500 nM for AMP was achieved with the as-prepared AgNP colloid. The bacterium Mycoplasma pneumoniae was also easily detected in laboratory culture with these SERS substrates. These findings attest to the applicability of this AgNP colloid for the sensitive and specific detection of both small biomolecules and microorganisms.     

A pair of new enantiomeric hybrid phthalide–adenines with a rare 5-oxa-1-azaspiro[3,4]octane moiety and two pairs of new enantiomeric hybrid paraethyl phenol–adenines from Ligusticum chuanxiong

Three pairs of new enantiomeric adenine alkaloids, (+)/(?)-liguadenines A–C [(+)/(?)-1–3], were isolated from the rhizome of Ligusticum chuanxiong Hort. The structures and absolute configurations of these compounds were determined using spectroscopic data, single-crystal X-ray diffraction, and electronic circular dichroism analyses. To the best of our knowledge, compounds (+)-1 and (?)-1 are the first hybrid phthalide–adenines to be ever reported. The linkage between the phthalide and adenine units in these compounds forms a rare 5-oxa-1-azaspiro[3,4]octane moiety. Analyses of the anti-inflammatory activities of the isolated compounds show that (+)/(?)-1 and (+)-3 exhibit significant inhibitory activity against LPS-induced TNF-α and IL-6 production in RAW264.7 cells. RT-qPCR analysis confirms that the most active compound, (+)-3, exerts anti-inflammatory activity by downregulating the mRNA expressions of TNF-α and IL-6 in the cells.