Interaction between alginates and manganese cations: identification of preferred cation binding sites.
Algal and bacterial alginates have been studied by means of 13C NMR spectroscopy in presence of paramagnetic manganese ions in order to reveal the nature of their interaction with bivalent cations. It is found that the mannuronate blocks bind manganese cations externally near their carboxylate groups, while guluronate blocks show the capability to integrate Mn2+ into pocket-like structures formed by adjacent guluronate residues. In alternating mannuronate-guluronate blocks, manganese ions preferentially locate in a concave structure formed by guluronate-mannuronate pairs. Partial acetylation of the alginate generally reduces its capability to interact with bivalent cations, however, the selectivity of the binding geometry is conserved. The results may serve as a hint for the better understanding of the alginate gelation in presence of calcium ions.
Emmerichs
N
N
Institut für Chemie, Universität Duisburg-Essen, 47057 Duisburg, Germany.
Wingender
J
J
Flemming
H-C
HC
Mayer
C
C
D000464:Alginates / Q000737:chemistry* / Q000378:metabolism*; D001665:Binding Sites; D002240:Carbohydrate Sequence; D002412:Cations; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008345:Manganese / Q000737:chemistry / Q000378:metabolism*; D008969:Molecular Sequence Data
D000464:Alginates; D002412:Cations; D008345:Manganese