Acid and enzymatic hydrolysis of the internal sialic acid residue in native and chemically modified ganglioside GM1.

The sialic acid of gangliosides not containing GalNAc (i.e., GM3, GD3) is readily hydrolyzed either enzymatically by sialidases or chemically in acid conditions.

Glycolipids noncovalently bound to DEAE-Sephadex. Use of the complexes for purification of IgM and IgG anti-(Gal beta 1-->3 GalNAc-) antibodies.

A method for the purification by affinity of antibodies of the IgM and IgG classes against the (Gal beta 1-->3 GalNAc-) epitope has been developed. The immunoadsorbent is based on the property of DEAE-Sephadex to bind acid glycolipids bearing this epitope, by electrostatic and hydrophobic interactions in a stable form in an aqueous medium. The acid glycolipid employed was asialo-GM1 ganglioside (GA1) derivatized to produce a carboxyl function on the olefinic bond of the sphingosine moiety (GA1 acid).

Differential interaction of Escherichia coli heat-labile toxin and cholera toxin with pig intestinal brush border glycoproteins depending on their ABH and related blood group antigenic determinants.

The ability of glycoproteins from pig intestinal brush border membranes (BBM) to bind cholera toxin (CT) or heat-labile toxins from strains of Escherichia coli isolated from human (LTh) or pig (LTp) intestines was studied. Glycoproteins capable of binding the toxins are also recognized by antibodies or lectins specific for ABO(H) blood group and related antigens. Pigs expressing A, H, or I antigenic determinants were used for comparison.

Myelin basic protein domains involved in the interaction with actin.

A fluorescence assay was used to measure the interaction of myelin basic protein (MBP) with monomeric actin labeled with a fluorescent compound (IAEDANS). The complex actin-IAEDANS increase the fluorescence in presence of MBP. The enhancement of the fluorescence has a sigmoidal dependence on the concentration of MBP and the fluorescence maximum is reached at a MBP:actin molar ratio of 1:20.

Escherichia coli heat-labile enterotoxin preferentially interacts with blood group A-active glycolipids from pig intestinal mucosa and A- and B-active glycolipids from human red cells compared to H-active glycolipids.

The capacity of cholera toxin (CT) and of the heat-labile enterotoxin produced by Escherichia coli isolated from humans (LTh) to interact with glycolipids bearing ABO(H) blood group determinants isolated from different sources and separated by thin layer chromatography was studied. Toxin binding to the ABO(H)-related glycolipids depends on the glycolipid source, the type of the blood group activity, and the toxin. LTh and CT were capable of interacting with several blood group-active glycolipids from pig intestinal mucosa and both toxins preferentially recognize glycolipids isolated from animals carrying A-blood group antigenic determinants compared to those isolated from animals lacking these antigens.