Interaction of mistletoe toxic lectin-I with sialoglycoproteins.
The binding properties of mistletoe toxic lectin-I (ML-I) with sialo-N- and O-glycans were investigated by quantitative precipitin and precipitin inhibition assays. Human alpha 1-acid glycoprotein reacted strongly with ML-I, precipitating over 82% of the lectin nitrogen tested, while the precipitability of its asialo product decreased by 30%. Native fetuin precipitated 50% of the ML-I added, and its reactivity was reduced by 20% after desialylation. On the contrary, the poor reactivity of rat sublingual sialoglycoprotein with ML-I increased substantially after removal of sialic acid and completely precipitated the lectin added. The glycoprotein-lectin interactions were inhibited by NeuAc alpha 2-->3/alpha 2-->6Gal beta 1-->4Glc and/or Gal beta 1-->4Glc (NAc) residues. From the above results, it is concluded that ML-I is specific for sialic acid. However, sialic acid of some O-glycans also acts as masking molecule as the precipitability of rat sublingual and bovine submandibular glycoproteins with ML-I increased after desialylation.
Wu
A M
AM
Glyco-immunochemistry Research Laboratory, Chang-Gung Medical College, Kwei-san, Tao-yuan, Taiwan.
Song
S C
SC
Hwang
P Y
PY
Wu
J H
JH
Pfüller
U
U
D000818:Animals; D002236:Carbohydrate Conformation; D002240:Carbohydrate Sequence; D004187:Disaccharides / Q000737:chemistry / Q000494:pharmacology; D006801:Humans; D007700:Kinetics; D037102:Lectins; D014784:Mistletoe; D008969:Molecular Sequence Data; D009844:Oligosaccharides / Q000737:chemistry* / Q000494:pharmacology; D009961:Orosomucoid; D037121:Plant Lectins; D028321:Plant Preparations; D010940:Plant Proteins; D010946:Plants, Medicinal; D011233:Precipitin Tests; D054790:Ribosome Inactivating Proteins, Type 2; D012795:Sialoglycoproteins / Q000737:chemistry*; D014118:Toxins, Biological / Q000302:isolation & purification; D000509:alpha-Fetoproteins
D004187:Disaccharides; D037102:Lectins; D009844:Oligosaccharides; D009961:Orosomucoid; D037121:Plant Lectins; D028321:Plant Preparations; D010940:Plant Proteins; D054790:Ribosome Inactivating Proteins, Type 2; D012795:Sialoglycoproteins; D014118:Toxins, Biological; D000509:alpha-Fetoproteins; C488862:mistletoe lectin I; C009674:ribosome inactivating protein, Viscum