J. Biol. Chem., Vol. 261, Issue 17, 7755-7761, 06, 1986
Interaction of sialoglycoproteins with wheat germ agglutinin-sepharose of varying ratio of lectin to Sepharose. Use for the purification of mucin glycoproteins from membrane extracts
K Furukawa, JE Minor, JD Hegarty and VP Bhavanandan
The influence of varying the amount of wheat germ agglutinin immobilized on
Sepharose beads on the binding of glycoproteins to these beads was
investigated. A series of wheat germ agglutinin-Sepharose gels containing
between 0.10 and 10.0 mg of lectin/ml of gel was prepared, and the actual
lectin content was established by acid hydrolysis of the gel followed by
analysis of glycine, a major amino acid in wheat germ agglutinin. Affinity
chromatography of labeled glycoproteins indicated that glycophorin bound to
all the wheat germ agglutinin-Sepharose preparations. Fetuin, ovomucoid,
and alpha 1-acid glycoprotein bound not at all or very poorly to gels with
a low content of wheat germ agglutinin (less than 0.95 mg/ml). The specific
binding of these glycoproteins increased with increasing lectin content on
the gels, and on gels of high content (greater than 3 mg/ml) the binding
was virtually quantitative. On chromatographing a mixture of glycophorin,
alpha 1-acid glycoprotein, fetuin, and ovomucoid on wheat germ
agglutinin-Sepharose, containing 0.08 mg of lectin/ml of gel, glycophorin
was selectively retained on the gel. It was possible to purify glycophorin
from an extract of human erythrocyte membranes in one step by
chromatography on the above gel. By using the series of gels, it was
demonstrated that Morris hepatoma 7777 membranes contained at least 4-fold
more sialoglycoproteins which bound to low density wheat germ
agglutinin-Sepharose compared to rat liver membranes. These hepatoma
sialoglycoproteins were isolated, purified, and partially characterized as
having a high proportion of O-linked sialyloligosaccharides. Our studies
illustrate the use of low density wheat germ agglutinin-Sepharose gels both
for the detection and for easy isolation of mucin-type glycoproteins from
crude extracts of cells or membranes.