N-脱甲基酶催化氧化咖啡因的反应机理

为研究恶臭假单胞菌CBB5降解咖啡因的反应机理,使用AutoDock和Vina软件完成咖啡因、茶碱及可可碱与N-脱甲基酶的分子对接工作,分析小分子配体与周围的氨基酸残基相互作用,并根据结合自由能及RMSD值分析最佳作用位点。结果表明,NdmA与咖啡因和茶碱之间存在π-π堆积作用,配体与受体结合较好,推测N282和F168为咖啡因和茶碱能够紧密结合在蛋白质的疏水空腔内的关键氨基酸残基,可以高效完成催化氧化作用。

Influence of intramolecular hydrogen bond formation sites on fluorescence mechanism

The fluorescence mechanism of HBT-HBZ is investigated in this work. A fluorescent probe is used to detect HClO content in living cells and tap water, and its structure after oxidation by HCl O(HBT-ClO) is discussed based on the density functional theory(DFT) and time-dependent density functional theory(TDDFT). At the same time, the influence of the probe conformation and the proton transfer site within the excited state molecule on the fluorescence mechanism are revealed. Combined with infrared vibrational spectra and atoms-in-molecules theory, the strength of intramolecular hydrogen bonds in HBT-HBZ and HBT-ClO and their isomers are demonstrated qualitatively. The relationship between the strength of intramolecular hydrogen bonds and dipole moments is discussed. The potential energy curves demonstrate the feasibility of intramolecular proton transfer. The weak fluorescence phenomenon of HBT-HBZ in solution is quantitatively explained by analyzing the frontier molecular orbital and hole electron caused by charge separation. Moreover, when strong cyan fluorescence occurs in solution, the corresponding molecular structure should be HBT-ClO(T). The influence of the intramolecular hydrogen bond formation site on the molecule as a whole is also investigated by electrostatic potential analysis.

拮抗菌诱导番茄根系分泌物鉴定及作用研究

微生物防治土传病害是目前最环保有效的手段。主要采用气相色谱质谱联用(GC-MS)技术和生物测定方法,检测绿针假单胞杆菌和短小芽孢杆菌的诱导对患灰霉病番茄植株生长速度、病情指数、抗氧化酶活性以及根系分泌物种类和相对含量的影响。结果表明两种拮抗菌可以直接抑制灰霉病生长,并且两种拮抗菌的诱导使患病番茄植株生长速度未受影响,其抗氧化酶活性受到破坏程度减小。GC-MS共检测出近30种根系分泌物,拮抗菌处理组中2-酮基-D-葡萄糖酸、2-羟基丙酸、苹果酸、十八酸、亚油酸、十二酸、对苯二甲酸、十六酸甲酯、邻苯二甲酸二异辛酯组分含量明显增加。综合来说,绿针假单胞杆菌和短小芽孢杆菌不仅本身可以直接抑制灰霉菌菌体的生长,当作用到番茄植物上同样有抑制灰霉病发病的作用,并且可以通过参加植株自身代谢,以及保护植株本身抗氧化酶活性改变植物次生代谢产物的种类和含量来达到抗病的效果,有效减轻体内氧化损伤。