title: Radioiodination of S-type lipopolysaccharide. Possibilities and limitations of labelling of the carbohydrate chain by periodate oxidation.
abstract: S-type Lipopolysaccharide (LPS) from E. coli O 139:K 82 (B) was radiolabelled by coupling 125I-tyramine to the carbohydrate chain of LPS after oxidation of sugar residues carrying vicinal hydroxy groups, with sodium metaperiodate. The specific activity amounted to 1.3 kBq/microgram LPS. As LPS is a mixture of molecules with different carbohydrate chain lengths that are associated to large micelles of high kinetic stability, the preparation and the properties of the tracer exhibit some peculiarities. Most important, partial cleavage of the carbohydrate chains of LPS is caused on radioiodination by the procedure described. As a consequence, the tracer differs markedly from the starting LPS with respect to carbohydrate chain length distribution. Another feature of special interest is the variation of the specific activity (radioactivity/unit mass) for LPS molecules of different carbohydrate chain lengths. Because of the kinetic stability of LPS micelles, the equilibration of radioiodinated and non-radioactive LPS aggregates requires their solubilization by a detergent and its subsequent removal by dialysis. It could be demonstrated that short-chain LPS molecules predominantly associate to larger micelles than long-chain molecules. Regardless of these restrictions, the 125I-LPS proved to be useful for certain analytical purposes.
authors.affiliation: Zentralinstitut für Isotopen- und Strahlenforschung, Berlin.
authors.forename: U
authors.initials: U
authors.lastname: Lachmann
authors.forename: W
authors.initials: W
authors.lastname: Schmidt
authors.forename: H
authors.initials: H
authors.lastname: Wunderlich
authors.forename: H
authors.initials: H
authors.lastname: Schäfer
mesh_terms: D050260:Carbohydrate Metabolism; D002850:Chromatography, Gel; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli; D006863:Hydrogen-Ion Concentration; D007553:Isotope Labeling / Q000379:methods*; D008070:Lipopolysaccharides / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D008823:Micelles; D010084:Oxidation-Reduction; D010504:Periodic Acid / Q000378:metabolism*; D012967:Sodium Dodecyl Sulfate
chemical_list: D008070:Lipopolysaccharides; D008823:Micelles; D010504:Periodic Acid; D012967:Sodium Dodecyl Sulfate; C009288:metaperiodate