The generation of reducing ends by exposure of hyaluronic acid to oxygen derived free radicals.
Enzymatic depolymerization of hyaluronic acid (HA) is accompanied by the release of reducing ends irrespective of the linkage cleaved. In this investigation we have examined HA exposed to oxygen-derived free radicals (oxy radicals) in order to determine whether reducing ends are released upon depolymerization. Reducing ends were detected by the assay of Park and Johnson, which is a non-specific but sensitive assay for reducing ends, but only to a minimal degree by the Reissig modification of the Morgan Elson reaction, which will detect N-acetylglucosamine at the reducing end. Exposure of a sample of HA, pre-exposed to streptomyces hyaluronidase, to an oxy radical flux did not result in a decrease in Morgan Elson reactivity thus indicating that post cleavage modification of the reducing end by further reaction with oxy radicals does not account for the lack of Morgan Elson reactivity. In addition reducing ends were also detected by reaction with radiolabelled cyanide to the degree predicted by molecular weight. These findings were interpreted as being consistent with the hypothesis that oxy radical induced depolymerization of HA occurs by preferential cleavage of the glucuronidic linkage thus leaving D-glucuronic acid at the reducing end.
McNeil
J D
JD
Wiebkin
O W
OW
Cleland
L G
LG
Vernon-Roberts
B
B
D005296:Ferrous Compounds; D005609:Free Radicals; D006820:Hyaluronic Acid; D006821:Hyaluronoglucosaminidase / Q000378:metabolism; D008970:Molecular Weight; D010084:Oxidation-Reduction; D010100:Oxygen; D011133:Polysaccharide-Lyases / Q000378:metabolism; D014969:Xanthine Oxidase
D005296:Ferrous Compounds; D005609:Free Radicals; D006820:Hyaluronic Acid; D014969:Xanthine Oxidase; D006821:Hyaluronoglucosaminidase; D011133:Polysaccharide-Lyases; C100002:hyaluronate lyase; D010100:Oxygen