Immunochemical studies on the N-acetyllactosamine β-(1→6)-linked trisaccharide specificity of Ricinus communis agglutinin

Albert M. Wu, Shunji Sugii, Flavio G. Gruezo, Elvin A. Kabat*

*Corresponding author for this work

Research output: Contribution to journalJournal Article peer-review

34 Scopus citations

Abstract

The combining site of Ricinus communis agglutinin (RCA1) was studied by quantitative precipitin and precipitin inhibition assays. Of 31 complex carbohydrates tested, all except active and inactive antifreeze glycoproteins, Streptococcus group C polysaccharide, and native rat salivary glycoprotein, reacted strongly, and 22 completely precipitated the lectin, indicating that RCA1 has both a broad range of affinity and a low solubility of its carbohydrate-bound complex. Of the monosaccharides and glycosides tested for inhibition of precipitation, p-nitrophenyl β-d-galactopyranoside was the best. It was about 6.4 times better than methyl β-d-galactopyranoside. The β anomer of glycosides of d-galactose was much more potent than the corresponding α anomer. Among the oligosacharides tested, β-d-Galp-(1→4)-β-d-GlcpNAc-(1→6)-d-Gal was the best inhibitor, which was ∼2/3 as active as p-nitrophenyl β-d-galactopyranoside. It was ∼1.4 times as active as β-d-Gal-(1→4)-d-GlcNAc (N-acetyllactosamine), twice as active as β-d-Gal-(1→3)-d-GlcNAc, and 4.5 times more active than lacto-N-tetraose. From the results, it can be concluded that; (a) hydrophobic interaction is important for binding; (b) the combining site of this lectin is at least as large as a trisaccharide; and (c) of the compounds studied, the trisaccharide β-d-Galp-(1→4)-β-d-GlcpNAc-(1→6)-d-Gal was the most complementary to the human blood group I Ma determinant β-d-Galp-(1→4)-β-d-GlcpNAc-(1→6)-d-Gal.

Original languageEnglish
Pages (from-to)243-257
Number of pages15
JournalCarbohydrate Research
Volume178
Issue number1
DOIs
StatePublished - 15 07 1988
Externally publishedYes

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