Analysis of saccharide binding to Artocarpus integrifolia lectin reveals specific recognition of T-antigen (beta-D-Gal(1----3)D-GalNAc).

摘要: The binding of Artocarpus integrifolia lectin to N-dansylgalactosamine (where dansyl is 5-dimethylaminonaphthalene-1-sulfonyl) leads a 100\% increase in fluorescence with concomitant blue shift the emission maximum by 10 nm. This carbohydrate-specific and has an association constant 1.74 \times $10^4 M^{-1}$ at $20^oC$. two sites for N-dansylgalactosamine. values -\Delta H S bindinogf are range reported severa monosaccharide interactions, indicating absence non-polar interaction dansylmoiety sugar combining region protein. Dissociation bound from its complex cosequent change on addition nonfluorescent sugars allowed evaluation competing ligands. thermodynamic parameters monosaccharides suggest that OH groups C-2, C-3, C-4, C-6 D-galactose configuration important loci lectin. acetamido group C-2 2-acetamido-2-deoxygalactopyranose methoxyl C-1 methyl-\gamma -Dgalactopyranoside presumably also involved through nonpolar van der Waals' interactions. T-antigenic disaccharide Gal\beta 1\rightarrow 3GalNAc binds very strongly lectinw hen compared methyl-\beta -D-galactopyranoside, \beta ( 3)-linked disaccharides such as 3GalNAc, (1\rightarrow 4)- linked disaccharides, N-acetyllactosamine andla ctose. major stabilizing force avid Tantigenic appears be favorable enthalpic contribution. site is, therefore, extended. These data takent ogether specific toward Thomsen-Friedenreich (T) antigen. There subtle differences overaltlo pography when peanut (Arachis hypogaea)agglutinin.The results stopped flow spectrometry consistent simple single-step bimolecular unimolecular dissociation rate processes. value $K_{+1}$ $K_{-1}$, $21 ^oC$ 8.1 X $10^5 M^{-1} s^{-1}$ 50 $s^{-1}$, respectively. activation indicate enthalpy-controlled process.