研究生 Students Cassandra Gates (left) and Emma Allen were among the Bryn Mawr students scheduled to give a poster presentation at the now-canceled National Meeting of the American Chemical Society.
当他们不能出席会议时, we wanted to share their abstracts and congratulate them on their achievements. Both students work in the lab of Professor of 化学 Sharon Burgmayer.
From Cassandra Gates: Protonation-induced redox reactivity in synthetic models of the mononuclear molybdenum cofactor
Molybdenum-dependent enzymes are present in almost every living organism and crucial for sustaining life. These enzymes complete oxygen atom transfers on a variety of substrates by utilizing a molybdenum cofactor (Moco) composed of a molybdenum metal center coordinated by one or two pyranopterin dithiolene ligands (MPT) conserved across all molybdoenzymes. A total of eight electron redox equivalents occurs between the Mo metal center and MPT, making Moco one of the most redox rich cofactors in all of biology. Due to the instability of Moco outside of the protein matrix, there is still little known about the contributions of MPT to catalytic function. It is clear, however, that without MPT, the enzyme loses all catalytic activity. In order to reveal the role of the MPT ligand in catalytic function, the Burgmayer lab has developed a family of synthetic models with the structure [TEA][Tp*Mo(X)(S2C2(pterin)(-C(CH3)2R)], TEA是四乙基铵, Tp* is tris(3,5-dimethylpyrazolyl)硼氢化物, X不是0就是S, R要么是羟基要么是甲基.
Recent studies utilize these synthetic models to investigate the reactivity of the pyranopterin upon protonation in the pyrazine ring. The protonated Mo-pterin-dithiolene model is redox reactive and readily participates in coupled proton-electron transfer with a variety of substrates, including dichlorophenolindophenol (DCIP) and the biologically relevant redox cofactor flavin adenine dinucleotide (FAD). Preliminary investigations into the reactivity of the model system with known Mo-enzyme substrates, 包括二甲基亚砜(DMSO)和硝酸盐, indicate that protonation may be sufficient to induce substrate reduction. The reactivity of this model system provides insight into the possible role of active-site hydrogen bonds to the pterin in enzymatic catalysis. 质子化反应这种质子化物质的合成, its reaction chemistry and our conclusions regarding the electronic structure changes resulting from pterin protonation will be described. Experimental results include reactions monitored using UV-Vis Spectroscopy, 各种形式的核磁共振, 傅立叶变换红外光谱, ESI-mass光谱法, 循环伏安法, gc -质谱法.
From Emma Allen: Making a Model for the Molybdenum Cofactor and Investigating Its Reaction 化学
Molybdenum (Mo) enzymes are required by almost every form of life and can be traced back to the first organism, “最后的普遍共同祖先”, 或卢卡. Mo enzymes have been linked to multiple human diseases, 适当的植物发展, and is crucial to the global cycling of the elements nitrogen and sulfur. 钼辅因子(Moco), composed of a molybdenum metal center and one or two pterin-dithiolene ligands, is the name of the active site in all molybdenum enzymes. 因为没有了蛋白质保护层，莫克就不稳定了, information about the role of the unusual pterin-dithiolene chelate is largely not available. To obtain some information regarding the chemical behavior of Mo bound to a pterin-dithiolene, the Burgmayer lab has synthesized a model system similar in structure to the biological Moco in order to explore the importance of the pterin, which is believed to play a role in the redox chemistry conducted by the cofactor. The work to be presented includes a description of the general synthesis of the pterin-dithiolene model system as well as two current investigations. The target model system is generally described as [TEA][Tp*Mo(X)(S2C2(pterin)(-C(CH3)2R)], TEA是四乙基铵, Tp* is tris(3,5-dimethylpyrazolyl)硼氢化物, X不是0就是S, R可以是羟基, 甲基或甲氧基. Current work is directed at developing the reaction chemistry of the model complex where R = OH which has previously been shown to undergo a reversible pyran cyclization. The first investigation studies the reactivity of the pyranopterin-dithiolene Mo complex upon protonation in the pyrazine ring. The protonated Mo-pterin-dithiolene model is redox reactive and readily participates in coupled proton-electron transfer with a variety of substrates. The second investigation explores the outcome of reacting the pyranopterin-dithiolene Mo complex with (PPh3I)+I- where initial spectroscopic results indicate a significant change in the electronic structure of the pterin-dithiolene.
文科研究生教育 环境
研究生 education at Bryn Mawr was part of the founding mission of the College. Established in 1885, 推荐全球十大博彩公司排行榜 takes pride in being the first institution in the U.S. to provide women a graduate education culminating in a Ph.D. 自1931年以来, graduate enrollment has been co-educational and today embraces inclusivity as one of its core values. Students in 艺术与科学研究生院 pursue research in graduate programs of international reputation.