SYNTHESIS AND IMMUNOCHEMISTRY OF FUCOSE METHYL ETHERS AND THEIR METHYLGLYCOSIDES

Characterization of the binding specificity of Anguilla anguilla agglutinin (AAA) in comparison to Ulex europaeus agglutinin I (UEA-I)

Using immunochemical and immunohistochemical methods, the binding site of Anguilla anguilla agglutinin (AAA) was characterized and compared with the related fucose-specific lectin from Ulex europaeus (UEA-I). In solid-phase enzyme-linked immunoassays, the two lectins recognized Fuc alpha 1-2Gal beta-HSA. AAA additionally cross-reacted with neoglycolipids bearing lacto-N-fucopentaose (LNFP) I [H type 1] and II [Le(a)] and lactodifucotetraose (LDFT) as glycan moieties. UEA-I, on the other hand, bound to a LDFT-derived neoglycolipid but not to the other neoglycolipids tested. Binding of AAA to gastric mucin was competitively neutralized by Le(a)-specific monoclonal antibodies. UEA-I binding, on the other hand, was reduced after co-incubation with H type 2- and Le(y)-specific monoclonal antibodies. According to our results, AAA reacts with fucosylated type 1 chain antigens, whereas UEA-I binds only to the alpha 1-2-fucosylated LDFT-derived neoglycolipid. In immunohistochemical studies, the reactivity of AAA and UEA-I in normal pyloric mucosa from individuals with known Lewis and secretor status was analysed. AAA showed a broad reaction in the superficial pyloric mucosa from secretors and non-secretors, but AAA reactivity was more pronounced in Le(a+b-) individuals. On the other hand, UEA-I stained the superficial pyloric mucosa only from secretor individuals. A staining of deep mucous glands by the lectins was found in all specimens. Both reacted with most human carcinomas of different origin. Slight differences in their binding pattern were observed and may be explained by the different fine-specificities of the lectins.

Synthesis of tetrasaccharides related to the antigenic determinants from the glycopeptidolipid antigens of serovars 9 and 25 in the Mycobacterium avium-M. intracellulare-M. scrofulaceum serocomplex

The synthesis of the tetrasaccharides O-(2,3-di-O-methyl-alpha-L-fucopyranosyl)-(1----4)-O-(2,3- di-O-methyl-alpha-L-fucopyranosyl)-(1----3)-O-alpha-L-rhamnopyranosyl -(1----2)-6-deoxyl-L-talose (36) and O-(2-O-methyl-alpha-L-fucopyranosyl)-(1----4)-O-(2-O-methyl-alpha-L- fucopyranosyl)-(1----3)-O-alpha-L-rhamnopyranosyl-(1----2)-6-deoxy-L- talose (41) is described. The former and the latter structures, respectively, have been proposed as the carbohydrate chains in the polar glycopeptidolipid antigens of serovars 9 and 25 in the Mycobacterium avium-M. intracellulare-M. scrofulaceum serocomplex. Glycosylation of allyl 2,3-di-O-methyl-alpha-L-fucopyranoside with 4-O-benzoyl-2,3-di-O-methyl-alpha-L-fucopyranosyl chloride gave the alpha-linked disaccharide derivative, which was O-deallylated and converted into the corresponding disaccharide alpha-chloride. This was coupled with benzyl 3,4-di-O-benzyl-6-deoxy-2-O-(2,4-di-O-benzoyl-alpha-L-rhamnopyranosyl)- alpha-L-talopyranoside (32) to give a fully protected tetrasaccharide derivative, which was deprotected to furnish 36. Likewise, 3-O-benzyl-4-O-(3,4-di-O-acetyl-2-O-methyl-alpha-L- fucopyranosyl)-2-O-methyl-alpha-L-fucopyranosyl chloride, prepared by way of condensation of allyl 3-O-benzoyl-2-O-methyl-alpha-L-fucopyranoside with 2-O-methyl-3,4-di-O-(p-nitrobenzoyl)-alpha-L-fucopyranosyl bromide, reacted with 32, to provide, after removal of blocking groups, 41.

A comparison of the binding specificities of lectins from Ulex europaeus and Lotus tetragonolobus

The L-fucose-binding lectins present in the seeds of Ulex europaeus and Lotus tetragonolobus have been isolated by affinity chromatography. The binding specificities of the lectins were compared by hemagglutination inhibition analysis. The lectins behaved similarly with respect to a variety of synthetic saccharides. D-Fucose derivatives were inactive as inhibitors. In general, the alpha -L-fucopyranosyl derivatives were better inhibitors than the beta-L-fucopyranosyl derivatives. Aromatic aglycones increased the inhibitory activity of the saccharides with p-nitrophenyl-alpha-L-fucopyranoside being one of the best inhibitors. The major difference between the two lectins was the observation that the Ulex lectin required higher concentrations of saccharides to bring about complete inhibition of hemagglutination than did the Lotus lectin.

The purification, composition and specificity of wheat-germ agglutinin

1. The purification of wheat-germ agglutinin from commercial wheat germ is described. By ion-exchange chromatography three active proteins (isolectins) were separated, one of which was examined in detail. 2. The amino acid composition is unusual, as 20% of residues are half-cystine and 21% are glycine. Unlike most lectins and contrary to previous reports, this protein is not a glycoprotein. 3. The efficiency of various saccharides as inhibitors of the agglutination reaction was investigated and from this the specificity of the binding site was inferred. Of monosaccharides, only derivatives of glucose with a 2-acetamido group and a free 3-hydroxyl group are effective inhibitors, and glycosides of either anomeric configuration are bound. Oligosaccharides are much more powerful inhibitors of agglutination than are monosaccharides. 4. It is proposed that the binding site consists of three or four subsites with differing specificities, in a cleft in the molecule resembling that proposed for hen's-egg-white lysozyme.

Blood group isoantibody stimulation in man by feeding blood group-active bacteria

It was investigated whether or not the human blood group isoantibodies A and B could be induced by immunogenic stimuli via natural routes with a kind of antigenic substance to which all humans are commonly exposed, or if the appearance of these antibodies is independent of antigenic stimuli as has long been believed. Escherichia coli O(86), which possess high human blood group B and faint A activity in vitro, were fed to healthy humans and those with intestinal disorders. 80% of the sick individuals of blood group O and A responded with a significant rise of anti-B antibodies which was frequently de novo in infants; significant increase of anti-A isoantibodies among blood group O individuals was less frequent. Over one-third of the healthy individuals also had a significant isoantibody increase. Intestinal lesions favor isoantibody stimulation by intestinal bacteria; this view was supported by the study of control infants. Persons of blood group A responded more frequently with anti-B and anti-E. coli O(86) antibody production than those of blood group O. Isoantibody increase was accompanied with antibody rise against E. coli O(86). Inhalation of E. coli O(86) or blood group AH(O)-specific hog mucin also evoked isoantibodies. The induced isoantibodies were specifically inhibited by small amounts of human blood group substances. E. coli O(86)-induced anti-blood group antibodies in germ-free chickens and preexisting blood group antibodies in ordinary chickens were neutralized by intravenous injection of E. coli O(86) lipopolysaccharide. This study demonstrates that human isoantibodies A and B are readily elicited via physiological routes, by blood group-active E. coli, provided the genetically determined apparatus of the host is responsive. Antibodies against a person's own blood group were not formed. Interpretation of these results permits some careful generalizations as to the origin of so-called natural antibodies.

Conformation of blood-group and virus receptor glycoproteins from red cells and secretions

Optical rotatory dispersion of human blood-group and virus receptor glycoproteins from erythrocytes and secretions was studied in the far-ultraviolet. Erythrocyte membrane blood-group glycoproteins, with potent virus receptor activities, contained significant alpha-helical and extended beta conformations, whereas the glycoproteins of secretions were largely disordered. These conclusions were supported by determination of the Moffitt constants (b(0)) and by measurements of circular dichroism.

Galactosidase Action on Human Blood Group B Active Escherichia coli and Ox Red Cell Substances

The blood group B specificity of Escherichia coli O(86) antigen, a B specific oligosaccharide fraction from it, and the B activity of a preparation of an "infectious mononucleosis receptor" from cattle erythrocytes are destroyed by alpha-galactosidase from the coffee bean, as demonstrated for the E. coli antigen by three methods. Blood group H(O) activity appears simultaneously. Galactose is the only hexose released from all three substances.