Characterization of methyl-, 3-deoxy-, and methyl-deoxysugars in marine high molecular weight dissolved organic matter | Characterization of methyl sugars, 3-deoxysugars and methyl deoxysugars in marine high molecular weight dissolved organic matter

Nuclear magnetic resonance spectroscopy of marine high molecular weightdissolved organic matter (HMWDOM) in surface waters show that >50% of the carbon isa compositionally well-defined family of acylated-polysaccharides that are conservedacross ocean basins. However, acid hydrolysis of HMWDOM followed bychromatographic analyses recover only 10-20% of the carbon as neutral, amino, andacidic sugars. Most carbohydrate in HMWDOM therefore remains uncharacterized.Here we use acid hydrolysis followed by Ag+ and Pb2+ cation exchange chromatographyto separate HMWDOM hydrolysis products for characterization by 1-D and 2-D NMRspectroscopy. In addition to neutral sugars identified in past studies, we find 3-Omethylglucose,3-O-methylrhamnose, 2-O-methylrhamnose and 2-O-methylfucose. Wealso find 3-deoxysugars to be present, although their complete structures could not bedetermined. Methyl sugars are widely distributed in plant and bacterial structuralcarbohydrates, such as cell wall polysaccharides, and their presence in HMWDOMsuggests that structural carbohydrates may contribute to DOM in surface seawater. Wefind most HMWDOM carbohydrate is not depolymerized by acid hydrolysis, and that thenonhydrolyzable component includes 6-deoxysugars.

Author Posting. © Elsevier B.V., 2007. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Organic Geochemistry 38 (2007): 884-896, doi:10.1016/j.orggeochem.2007.02.005.

Funding was provided by the Ocean Carbon Sequestration ResearchProgram, Biological and Environmental Research (BER), U.S. Department of Energygrant DEFG0200ER62999 and the National Sciences Foundation ChemicalOceanography Program grant OCE 9818654. Christos Panagiotopoulos received supportthrough the Postdoctoral Fellowship Program of the Woods Hole OceanographicInstitution, and DJR received support through the Stanley Watson Chair inOceanography.