Am. Wu et al., FURTHER CHARACTERIZATION OF THE BINDING-PROPERTIES OF A GALNAC SPECIFIC LECTIN FROM CODIUM FRAGILE SUBSPECIES TOMENTOSOIDES, Glycobiology, 7(8), 1997, pp. 1061-1066
Previous study on the binding properties of a lectin isolated from Cod
ium fr agile subspecies tomentosoides (CFT) indicates that this lectin
recognizes the GalNAc alpha 1--> sequence at both reducing and nonred
ucing ends, In this study, the carbohydrate specificity of CFT was fur
ther characterized by quantitative precipitin (QPA) and inhibition of
lectin-enzyme binding assays, Of the glycoforms tested for QPA, all as
ialo-GalNAc alpha 1--> containing glycoproteins reacted well with the
lectin, Asialo hamster and ovine submandibular glycoproteins, which co
ntain almost exclusively Tn (GalNAca alpha 1-->Ser/Thr) residues as ca
rbohydrate side chains, and Streptococcus type C polysaccharide comple
tely precipitated the lectin added, while the GalNAc beta 1-->containi
ng Tamm-Horsfall Sd(a(+)) glycoprotein and its asialo product were ina
ctive, Among the oligosaccharides tested for inhibiting lectin-glycopr
otein interaction, GalNAc alpha 1-->3GalNAc beta 1-->3Gal alpha 1-->4G
al beta 1--> 4Glc(Fp) and Gal beta 1-->3GalNAc alpha 1-->benzyl (T alp
ha) were the best, and about 125-fold more active than GalNAc, They we
re about 3.3, 6.6, and 43 times more active than Tn containing glycope
ptides, GalNAc alpha 1-->3(LFuc alpha 1--> 2)Gal(A(h)) and Gal beta 1-
->3GalNAc(T), respectively, From the present and previous results, it
is concluded that the combining site of CFT is probably of a groove ty
pe that recognizes from GalNAc alpha l--> to pentasaccharide(Fp). The
carbohydrate specificity of this lectin can be constructed and summari
zed in decreasing order by lectin determinants as follows: Fp and T al
pha > Tn cluster > A(h) >> I/II.