title: Comparison of water exposed area of cholera toxin when free in solution and bound to liposomes containing the ganglioside GM1.
abstract: Membrane impermeable diazocoupling reagents were used for studying the water exposure of subunits (alpha, beta, gamma) of cholera toxin (CT) when bound to liposomes containing the ganglioside GM1 (Lip-GM1). The interaction between CT with Lip-GM1 shielded the binding region in particular, since a maximum of one amino acid residue on each beta subunit was modifiable. When CT was labeled free in solution five residues of each beta subunit can be coupled, but it produced loss of binding ability. New area of beta subunit was exposed to reagents after having removed alpha subunit. This labeling may serve as a tool to assess the topology of CT upon binding with Lip-GM1.
mesh_terms: D055598:Chemical Phenomena; D002627:Chemistry, Physical; D002772:Cholera Toxin; D003979:Diazonium Compounds; D004220:Disulfides; D005677:G(M1) Ganglioside; D005732:Gangliosides; D008081:Liposomes; D046911:Macromolecular Substances; D012996:Solutions; D014867:Water
chemical_list: D003979:Diazonium Compounds; D004220:Disulfides; D005732:Gangliosides; D008081:Liposomes; D046911:Macromolecular Substances; D012996:Solutions; D014867:Water; D005677:G(M1) Ganglioside; C007308:diazodiiodosulfanilic acid; D002772:Cholera Toxin