C6 Carboxylate Groups Research Articles

Immunochemical examination of the Pseudomonas aeruginosa glycocalyx: a monoclonal antibody which recognizes L-guluronic acid residues of alginic acid.

Mice immunized with Formalin-fixed mucoid Pseudomonas aeruginosa cells developed an immune response directed, in part, towards the P. aeruginosa glycocalyx. The polyclonal mouse sera produced good immunofluorescent staining of the P. aeruginosa glycocalyx and cell surface. A library of 250 hybridoma cell lines which produced monoclonal antibodies directed against P. aeruginosa was established. Twelve clones (4.8%) produced antibody which reacted with alginate in an enzyme-linked immunosorbent assay (ELISA). Clone Ps 53 was chosen for further study, cloned, and an ascites tumor established. Clone Ps 53 was chosen for further study because the antibody produced demonstrated a specificity similar to that of a recently isolated heparin--rat-lung lectin which recognizes alginates of the Homma nontypable P. aeruginosa strains. The Ps 53 clone produced an immunoglobulin M which reacted with P. aeruginosa alginate and produced good immunofluorescent staining of the P. aeruginosa glycocalyx. The Ps 53 monoclonal antibody has an apparent specificity for L-guluronic residues in ELISA. Competitive binding studies with various alginates and monosaccharides suggest that the C6 carboxyl group of uronic acids are recognized by the antibody and that the antigen-binding site is fairly large and may recognize a particular sequence or epitope of alginic acid which is rich in L-guluronic acid. The Ps 53 monoclonal antibody did not react uniformily with all P. aeruginosa alginates but did react with all of the alginates of the Homma nontypable strains tested, suggesting that acetylation or various modifications found in P. aeruginosa alginates may interfere with antibody binding and define specific epitopes. The Ps 53 antibody also reacted with purified outer membrane, indicating that some alginate or L-guluronic acid is intimately associated with outer membrane.

Detection of the Sanfilippo type B syndrome using radiolabelled oligosaccharides as substrates for the estimation of α- N-acetylglucosaminidase

1. 1. The following radiolabelled disaccharides were prepared from heparin and evaluated as substrates for α- N-acetylglucosaminidase present in cultured skin fibroblasts: O-(α-2- acetamido-2- deoxy- d-glucopyranosyl )-(l → 4)- l -[6, 3 H]idose (GlcNAc-Ido), O-(α-2- acetamido-2- deoxy- d-glucopyranosyl )-(l '→ 4)-1,6 anhydro- l-6, 3H] idose (GlcNAc-anldo), O-(α-2- acetamido-2- deoxy- d-glucopyranosyl )-(1→ 4)-L-[6, 3 H] idose 2-sulfate (GlcNAc-Ido(OS)), O-(α-2- acetamido-2- deoxy- d-glucopyranosyl )-(l → 3)- l -[6, 3 H] idonic acid (GlcNAc-IdOA). 2. 2. α- N-Acetylglucosaminidase activity assessed with GlcNAc-IdOA was 12 times higher than the values obtained using GlcNAc-Ido, GlcNAc-anldo and GlcNAc-Ido(OS). Less than 5% of normal activity resulted when these substrates were incubated with fibroblasts from Sanfilippo B patients. These results demonstrate that a C6 carboxyl group on the adjacent residue to the N-acetylglucosaminide moiety is an important structural requirement in the mechanism of action or binding of α- N-acetylglucosaminidase toward α-linked N-acetylglucosaminide residues. The presence of a C2 sulfate group on the adjacent residue had no effect on enzyme activity. 3. 3. α- N-Acetylglucosaminidase activity in leucocyte and fibroblast homogenates assayed using GlcNAc-IdOA as substrate clearly distinguished Sanfilippo B patients from normal controls, and Sanfilippo A, C and D patients.