Characterization of mono-, di-, and tri-O-acetylated sialic acids on human cells.
The presence of mono-, di-, and tri-O-acetylated sialic acids on human cells was demonstrated by using radiochromatographic and chemical techniques. Human melanoma cells and fresh colon tissue were biosynthetically labeled with 6- (3H) glucosamine. Radiolabeled sialic acids were hydrolytically removed from cellular glycoconjugates, purified by ion-exchange chromatography, and separated by paper chromatography on the basis of the number of O-substitutions on each sialic molecule. This analytical technique characterized radiolabeled sialic acids that migrated with the same Rf as synthetic mono-, di-, and tri-O-acetylated 14C-labeled sialic acids. The mono-O-acetylated sialic acids were characterized by their sensitivity to sodium periodate oxidation and a crude mouse liver esterase preparation. The di- and tri-O-acetylated sialic acids were characterized by their resistance to sodium periodate oxidation and sensitivity to the action of crude mouse liver esterase. Chromatographically separated di- and tri-O-acetylated sialic acids from normal human colon tissue were characterized by their respective ion molecular weights by using fast-atom bombardment-mass spectrometry. Using these methods, we chemically characterized mono, di-, and tri-O-acetylated sialic acids expressed on human cells. Aberrant expression of O-acetylated sialic acids was associated with adenocarcinoma of the colon, leading to a nearly complete loss of di- and tri-O-acetylated sialic acids.
Hutchins
J T
JT
Department of Hematology, University of Texas M.D. Anderson Hospital and Tumor Institute at Houston 77030.
Reading
C L
CL
D000107:Acetylation; D000818:Animals; D002854:Chromatography, Paper; D006801:Humans; D006868:Hydrolysis; D013058:Mass Spectrometry; D008545:Melanoma / Q000378:metabolism; D051379:Mice; D012794:Sialic Acids / Q000378:metabolism*; D014407:Tumor Cells, Cultured / Q000378:metabolism
D012794:Sialic Acids