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Reiko T Lee

Publications and source records attributed to Reiko T Lee.

5 recordsLinked to original sources
PubMed2002

Carbohydrate-binding properties of human neo-CRP and its relationship to phosphorylcholine-binding site.

Binding characteristics of two types of ligands for human neo-C-reactive protein (neo-CRP), which is a conformationally altered but physiologically relevant form of CRP, were studied fluorometrically by probing CRP immobilized on a polystyrene surface with europium-labeled ligands. Two Eu-ligands used were bovine serum albumin derivatives that contain on average 40 residues of ligand structures, one derivative containing phosphorylcholine (PC) and the other lactosyl residues. The PC-containing ligands required the presence of calcium for binding, whereas galactose-containing derivatives bound in the absence of calcium. The optimal pH for the PC-dependent binding was broad (pH 6-8), whereas the best binding pH for the galactose-dependent binding was around 6. The carbohydrate-mediated binding is rather nonspecific: the binding site prefers galactose configuration, but other hexoses can be accommodated. The two best monosaccharide inhibitors at this site were galactose-6-phosphate and galacturonic acid, suggesting the importance of having a negatively charged group at C-6 position of galactose. In fact, the phosphate-binding site is common to both PC and sugar phosphates, and the choline- and the sugar-binding sites are probably located on either side of the phosphate-binding site. Binding characteristics of Eu-labeled PC-BSA to neo-CRP are quite similar to that found for native CRP in solution phase [Lee et al. (2002) J. Biol. Chem., 277, 225-232], whereas binding of sugar phosphates by neo-CRP shows considerably less stringent requirements compared to native CRP. For instance, galactose-alpha1-phosphate was not inhibitory at all in the native CRP binding assay, whereas it was a good inhibitor in the neo-CRP assay.

Binding Sites↗
PubMed2002

Inhibition of adhesion of type 1 fimbriated Escherichia coli to highly mannosylated ligands.

The inhibitory potencies of a number of mannosides, di- and trivalent mannosides, a set of mannose-terminating dendrimers, and five types of mannose-bearing neoglycoproteins were determined by using a binding assay that measures the binding of (125)I-labeled, highly mannosylated neoglycoprotein to a type 1 fimbriated Escherichia coli (K12) strain in suspension. The IC(50) values (the concentration of inhibitor that causes 50 % reduction in the bound (125)I-ligand to E. coli) obtained by this method were much lower than the equivalent values obtained by hemagglutination or in assays that involve microplate immobilization. Two important factors that strongly influence the affinity to E. coli adhesin are: 1) the presence of an alpha-oriented aglycon that has a long aliphatic chain or an aromatic group immediately next to the glycosyl oxygen, and 2) the presence of multiple mannosyl residues that can span a distance of 20 nm or longer on a relatively inflexible structure. The two best inhibitors, which are a highly mannosylated neoglycoprotein with the longest linking arm between a mannose and protein amino group and the largest mannosylated dendrimer (fourth generation), exhibited sub-nM IC(50) values.

Adhesins, Escherichia coli↗
PubMed2001

Mapping the binding areas of human C-reactive protein for phosphorylcholine and polycationic compounds. Relationship between the two types of binding sites.

We developed a fluorescence-based assay method for determining ligand binding activities of C-reactive protein (CRP) in solution. Using this method, we compared the phosphorylcholine (PC)- and polycation-based binding activities of human CRP. The PC-based binding required calcium, whereas a polycation (e.g. poly-l-lysine) was bound in the presence of either calcium or EDTA, the binding being stronger in the presence of EDTA. The published crystallographic structures of CRP and the CRP.PC complex show it to be a ring-shaped pentamer with a single PC-binding site per subunit facing the same direction. As expected from such a structure, binding affinity of a ligand increased tremendously when multiple PC residues were present on a macromolecular structure. In addition to PC-related structures, certain sugar phosphates (e.g. galactose 6-phosphate) are bound near the PC-binding site, and one of the sugar hydroxyl groups appears to interact with CRP. The best small ligands for the polycationic binding site were Lys-Lys and Lys4. Because of the presence of multiple Lys-Lys sequences, polylysines have tremendously enhanced affinity. Although PC inhibits both PC- and polycation-based binding, none of the amines that inhibit polylysine binding inhibits PC binding, suggesting that the PC and polycationic binding sites do not overlap.

Binding Sites↗