and to develop mass spectrometry methods for the identification of all possible methylated amino acids for future metabolomic studies. In this study, all N‐methyl and N,N‐dimethyl amino acids were synthesized by the methylation of α‐amino acids and characterized by a GC‐MS method. The methylated amino acids were derivatized with ethyl chloroformate and analyzed by GC‐MS under EI and methane/CI conditions
甲基化是生物系统中必不可少的代谢过程,对于活生物体中的几种生物反应而言都非常重要。已知甲基化化合物参与大多数身体功能,其中一些充当生物标记。从理论上讲,所有α-氨基酸都可以被甲基化,并且在大多数动植物样品中都可能遇到。但是分析数据,尤其是质谱数据,仅可用于少数甲基化氨基酸。因此,至关重要的是产生质谱数据并开发质谱方法以鉴定所有可能的甲基化氨基酸,以用于未来的代谢组学研究。在这项研究中,所有N-甲基和N,N二甲基氨基酸是通过α-氨基酸的甲基化合成的,并通过GC-MS方法进行了表征。甲基化的氨基酸用氯甲酸乙酯衍生化,并在EI和甲烷/ CI条件下通过GC-MS分析。N-甲基(1-18)和N,N-二甲基氨基酸(19-35)的氯甲酸乙酯衍生物的EI质谱显示出丰富的[M-COOC 2 H 5 ] +离子。由于[M-COOC 2 H]中的C 2 H 4,CO 2((CO 2 + C 2 H 4))的损失而产生的碎片离子5
A Plausible Prebiotic Origin of Glyoxylate: Nonenzymatic Transamination Reactions of Glycine with Formaldehyde
prebiotic availability of glyoxylate has not as yet been demonstrated. Herein we report the formation of glyoxylate by means of a transamination reaction between glycine and formaldehyde in water at 50 °C and 70 °C at pH 8 and 6, respectively. The reaction was followed by means of 13C NMR and high-resolution mass spectrometry employing both unlabeled and 13C-labeled reactants. Other products accompanying
Synthesis of a highly potent leukocyte function-associated antigen-1 antagonist and its metabolite labeled with stable isotopes and carbon-14, part 2
作者:Bachir Latli、Matt Hrapchak、Yibo Xu、Fenghe Qiu、Dhileepkumar Krishnamurthy、Chris H. Senanayake
DOI:10.1002/jlcr.1934
日期:2011.11
[13C2]-glycine in 15 steps and 2.5% overall yield. With the availability of [13C6]-3,5-dichloroaniline, the sulfonamide [13C6]-(2) was prepared in 12 steps and in 5.6% overall yield. For the carbon-14synthesis, a six-step synthesis gave both compounds [14C]-(1) and [14C]-(2) from the common sulfonyl chloride intermediate [14C]-(15) in 18% and 4% radiochemical yields and specific activities of 44 and 40.5 mCi/mmol
Syntheses of C-13 and C-14-labeled versions of the investigational proteasome inhibitor MLN9708
作者:Mihaela Plesescu、Eric L. Elliott、Yuexian Li、Shimoga R. Prakash
DOI:10.1002/jlcr.3079
日期:2013.7
inhibitor that is under development by Millennium in clinical studies in both hematologic and nonhematologic malignancies. The stable isotope-labeled MLN9708 was required for bio-analytical studies. [(13) C9 ]-MLN9708 (11) was synthesized in seven steps from the uniformly labeled [(13) C6 ]-1,4-dichlorobenzene (3) and [1-(13) C]-acetyl chloride. Because of the presence of two chlorine atoms and a boron atom
A Flavoprotein Dioxygenase Steers Bacterial Tropone Biosynthesis via Coenzyme A-Ester Oxygenolysis and Ring Epoxidation
作者:Ying Duan、Marina Toplak、Anwei Hou、Nelson L. Brock、Jeroen S. Dickschat、Robin Teufel
DOI:10.1021/jacs.1c04996
日期:2021.7.14
Bacterial tropone naturalproducts such as tropolone, tropodithietic acid, or the roseobacticides play crucial roles in various terrestrial and marine symbiotic interactions as virulence factors, antibiotics, algaecides, or quorumsensing signals. We now show that their poorly understood biosynthesis depends on a shunt productfrom aerobic CoA-dependent phenylacetic acid catabolism that is salvaged
细菌托酚酮天然产物,如托酚酮、托托二硫代酸或玫瑰杀菌剂,在各种陆地和海洋共生相互作用中起着至关重要的作用,如毒力因子、抗生素、除藻剂或群体感应信号。我们现在表明,它们知之甚少的生物合成依赖于需氧 CoA 依赖性苯乙酸分解代谢的分流产物,该分流产物由专用的酰基辅酶 A 脱氢酶样黄素酶 TdaE 挽救。TdaE 的进一步表征揭示了一种意想不到的复杂催化,包括底物脱氢、非经典 CoA-酯氧解和最终环氧化。因此,该酶作为一种典型的黄素蛋白双加氧酶发挥作用,它结合了来自 O 2的两个氧原子进入底物,最有可能涉及黄素-N5-过氧化物和黄素-N5-氧化物物质,分别用于连续的 CoA-酯裂解和环氧化。随后反应性酶产物的自发脱羧产生托酚酮,它是由病原性土壤植物伯克霍尔德菌引起的水稻穗枯病的关键毒力因子。或者, TdaE产物最有可能转化为更复杂的含硫次生代谢物,例如来自主要海洋红杆菌科(如抑制嗜热菌)的原二硫代硫酸。