报告题目：New forms of dissolved organic nitrogen identified by multibond two-dimensional nuclear magnetic resonance spectroscopy coupled with isotopic labeling
报告人：Dr. Jingdong Mao, Department of Chemistry and Biochemistry, Old Dominion University, Norfolk, VA, 23529, USA
报告时间：2017.03.15下午15：30-16：30
报告地点：理学院报告厅
报告摘要：
Dissolved organic nitrogen (DON) comprises the largest pool of fixed N in the surface ocean, yet its composition remains poorly constrained. An understanding of the chemical composition of this nitrogen pool is crucial for understanding its biogeochemical function and reactivity in the environment. Previous work has suggested that high molecular-weight (high-MW) DON exists in only two closely related forms, the secondary amides of peptides and of N-acetylated hexose sugars. Here, we demonstrate that the chemical structures of high-MW DON are much more diverse than previously thought. We couple isotopic labeling of cyanobacterially-derived dissolved organic matter with advanced two-dimensional nuclear magnetic resonance spectroscopy, for the first time, to open the ‘black box’ of uncharacterized DON. We have identified novel N-methyl containing amines and amides, primary amides, and novel N-acetylated sugars, which account for nearly 50% of high-MW DON. This study reveals unprecedented compositional details of the previously uncharacterized DON pool and outlines the means to further advance our understanding of this biogeochemically and globally important pool of nitrogen in nature.