title: Calcium ion binding of three different types of oligo/polysialic acids as studied by equilibrium dialysis and circular dichroic methods.
abstract: Ca2+ binding properties of three different types of oligo/polysialic acid chains, i.e., oligo/poly(Neu5Ac), oligo/poly(Neu5Gc), and oligo/poly(KDN), were studied by equilibrium dialysis and circular dichroism. Colominic acid, high molecular weight polysialoglycoprotein (H-PSGP), low molecular weight polysialoglycoprotein (L-PSGP), and 3-deoxy-D-glycero-D-galacto-2-nonulosonic acid (KDN) glycoprotein were found to bind calcium ions with about 8-100 times the affinity of sialic acid monomer. Analysis by equilibrium dialysis of the binding of Ca2+ to colominic acid was biphasic, and the high-affinity interaction was shown to change with the degree of polymerization. Specific binding of Ca2+ to polysialic acid (polySia) caused characteristic effects in the circular dichroism spectrum. A pronounced decrease in the circular dichroism of polySia at 205 nm was observed upon addition of calcium. H-PSGP was found to bind calcium ions with 3-fold higher affinity than L-PSGP.
authors.affiliation: Department of Biophysics and Biochemistry, Faculty of Science, University of Tokyo, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Shimoda
authors.forename: K
authors.initials: K
authors.lastname: Kitajima
authors.forename: S
authors.initials: S
authors.lastname: Inoue
authors.forename: Y
authors.initials: Y
authors.lastname: Inoue
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002240:Carbohydrate Sequence; D002942:Circular Dichroism; D003956:Dialysis; D008969:Molecular Sequence Data; D011134:Polysaccharides / Q000378:metabolism; D012794:Sialic Acids / Q000378:metabolism*; D012795:Sialoglycoproteins / Q000378:metabolism; D014337:Trout
chemical_list: D011134:Polysaccharides; D012794:Sialic Acids; D012795:Sialoglycoproteins; C014420:colominic acid; D002118:Calcium