ARS | Publication request: OXIDATION AND METAL ION AFFINITIES OF A NOVEL CYCLIC TETRASACCHARIDE

Submitted to: Carbohydrate Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 31, 2003
Publication Date: October 31, 2003
Citation: Dunlap, C.A., Cote, G.L., Momany, F.A. 2003. Oxidation and metal ion affinities of a novel cyclic tetrasaccharide. Carbohydrate Research. 338:2367-2373.

Interpretive Summary: A cyclic tetrasaccharide, derived from enzymatic treatment of carbohydrate polymers, was modified and screened for the ability to bind metal ions. Metal chelators find broad use in medicine, nutrition, environmental remediation, and industrial products. This study demonstrates the synthesis and metal ion binding properties of the modified cyclic tetrasaccharide. The results show it is a selective chelator for lead, which may have potential commercial applications.

Technical Abstract: The cyclic tetrasaccharide cyclo-{-6)-alpha-D-Glcp-(1-3)-alpha-D-Glcp-(1-6)-alpha-D-Glcp-(1-3)-alpha-D-Glcp-(1-} was oxidized in high yield to a dicarboxylic acid, cyclo-{-6)-alpha-D-Glcp-(1-3)-alpha-D-GlcpA-(1-6)-alpha-D-Glcp-(1-3)-alpha-D-GlcpA-(1-}. The parent and oxidized compound were then screened for the ability to form stable complexes with 20 metal cations. Ion-exchange thin layer chromatography was utilized to survey binding in aqueous and 50% methanol solutions. The screening identified Pb**2+, Fe**2+, and Fe**3+ as forming strong metal chelates with the oxidized cyclic tetrasaccharide. The stoichiometry of the oxidized cyclic tetrasaccharide and Pb**2+ complex was determined to be 1:1 using aqueous gel-permeation chromatography. Perturbations between the free and complexed structure were examined using NMR spectroscopy. Molecular simulations were used to identify a probable structure of oxidized cyclic tetrasaccharide complexed with Pb**2+.