简单的二元羧酸:己二酸(1),琥珀酸(2)和丙二酸(3);制备了具有两个丙酸基团的更复杂的线性四吡咯:mesobiliverdin-XIIIα(4)和mesobilirubin-XIIIα(5),以及在C 10(6)具有宝石-二甲基的红宝石类似物,其99 C 13 CO 2 H基团。由水和H 2 O-(CD 3)2 SO溶液中的滴定曲线确定其p K a值:羧基碳13图C-NMR化学位移随p H的变化而变化。在H 2 O中具有已知p K a的二酸1-3的滴定曲线用作测定四吡咯二酸4-6的p K a s的校准标准:p K a1 = 3.9,对于4,p K a2 = 5.3 ;p K a1 = 4.2,p K a2 = 4.9(5),p K a1 = 4.7,p K a2 = 5.7H 2 O中的6。
在这项工作中,引入了一种改进的核酸稳定同位素标记方案。新颖的构建模块消除/最小化同核 (13) C 和 (1) H 标量耦合,从而允许质子弛豫分散 (RD) 实验准确报告核酸的化学交换。使用位点特异性 (2) H 和 (13) C 标记,将自旋拓扑引入 DNA 和 RNA 中,使 (1) H 弛豫分散实验能够以简单的方式应用。新型 RNA/DNA 构建模块已成功整合到两种核酸中。先前显示 A 位点 RNA 在微秒至毫秒的时间内经历了两个位点交换过程。使用质子弛豫色散实验,可以概括之前确定的交换参数,从而验证所提出的方法。我们进一步研究了 cTAR DNA 的动力学,cTAR DNA 是一种参与 HIV-1 病毒复制周期的 DNA 转录物。同样,交换过程可以被表征和量化。这显示了新标记方案对于(1)核酸HRD实验的普遍适用性。
Cyanoketene: the microwave spectrum and structure of an unstable molecule
作者:M. Hahn、H.-K. Bodenseh、M. Ferner
DOI:10.1016/j.jms.2003.10.010
日期:2004.2
Abstract The unstablemolecule cyanoketene has been prepared by pyrolysis in a flow system, and the microwave spectra of five isotopic species, a - and b -type, have been measured in the frequency range from 8 to 40 GHz. Precise rotational constants and centrifugal distortion parameters up to the sixth order were obtained. The molecule has been shown to be planar, and a reliable structure was derived
摘要 在流动系统中通过热解制备了不稳定分子氰基烯酮,并在 8 至 40 GHz 的频率范围内测量了 a 型和 b 型五种同位素的微波光谱。获得了精确到六阶的旋转常数和离心畸变参数。该分子已被证明是平面的,并推导出了一个可靠的结构。N-四极耦合常数和偶极矩分量也已确定。结果可能是该分子星际光谱的基础。
The Source of “Fairy Rings”: 2-Azahypoxanthine and its Metabolite Found in a Novel Purine Metabolic Pathway in Plants
members of the purinemetabolicpathway in animals, plants, and microorganisms. However, further metabolism of AICA remains elusive. Based on these results and facts, we hypothesized that plants themselves produce AHX and AOH through a pathway similar to the chemical synthesis. Herein, we demonstrate the existence of endogenous AHX and AOH and a novelpurinepathway to produce them in plants.
applied in several NMRstudies to study the E/Z ratio in different matrices. In solution, such as DMSO, a dynamic equilibrium between E/Z-isomers (ratio of 8:92) was determined by initial 13 C-carbon NMR experiments. To get insights into the E/Z ratio of teriflunomide under "in-vivo" conditions, advanced heteronuclear NMR (HOESY) in D2 O and mixtures of D2 O/plasma were performed. While NMR experiments in
Synthesis of (6-<sup>13</sup>C)Pyrimidine Nucleotides as Spin-Labels for RNA Dynamics
作者:Christoph H. Wunderlich、Romana Spitzer、Tobias Santner、Katja Fauster、Martin Tollinger、Christoph Kreutz
DOI:10.1021/ja302148g
日期:2012.5.2
blocks, site-specific labels can be incorporated into a target RNA via chemical oligonucleotide solid-phase synthesis. This labeling scheme is particularly useful for studying milli- to microsecond dynamics via NMR spectroscopy, as an isolated spin system is a crucial prerequisite to apply Carr-Purcell-Meiboom-Gill (CPMG) relaxation dispersion type experiments. We demonstrate the applicability for the
作者:Alvarado, Luigi J.、Longhini, Andrew P.、Leblanc, Regan M.、Chen, Bin、Kreutz, Christoph、Dayie, T. Kwaku
DOI:10.1016/b978-0-12-801122-5.00007-6
日期:——
such as selective labeling of the ribose C1' and C5' and the pyrimidine nucleobase C2, C4, C5, or C6. Biomass-produced, uniformly or selectively labeled NTPs offer a third method, but suffer from low overall yield per labeled input metabolite and isotopic scrambling with only modest suppression of (13)C-(13)C couplings. In contrast to these four methods, our current chemo-enzymatic approach overcomes