Studies of N-linked oligosaccharide chains of α1-acid glycoprotein from ascitic fluid of stomach cancer patients and normal serum.
Experim. Oncol., 15 (5), pp. 53 - 61, (1993)
Human α1-acid glycoprotein (AGP) with apparent molecular weight 44 kDa was isolated from normal human serum (n-AGP) and ascitic fluid, of patients with stomach cancer (a-AGP), Both AGPs yielded single bands in SDS-electrophoresis and immunodiffusion. Aminoacid compositions of both AGPs were similar, but carbohydrate ones were different as well as their affinity to Con A. A comparative study of the structure of a-AGP and n-AGP N-glycans was carried out by HPLC analysis with two types of column's (OS-mapping) in the combination with their sequential exoglycosidase digestion. N-glycans were released by hydrazinolysis or by treatment with LiBH4 - LiOH - tret-BuOH and subjected to reductive amination with a fluorescent reagent, 7-amino-4-methylcoumarine (AMC) in the presence of LiBH3CN. The mixture of labeled OSs obtained (AMC-OS) was analysed by HPLC; n-AGP and a-AGP had identical glycan composition but the amounts of biantennary glycans, agalacto-oligosaccharides as well as the content of Lex-fragments in a-AGP were increased.