title: Specificity of Amaranthus leucocarpus syn. hypocondriacus lectin for O-glycopeptides.
abstract: Amaranthus leucocarpus syn. hypochondriacus lectin (ALL) has been shown to be specific for N-acetyl-D-galactosamine (GalNAc). In this work, we determined a value of 1.0 x 10(-2) M for the association constant of ALL for GalNAc, calculated using fluorescence spectroscopy assays. Using neoglycopeptides obtained by in vitro O-glycosylation, we determined the main features of O-glycopeptides recognized by ALL using molecular dynamics simulations, capillary electrophoresis, and ELISA. Neo-glycopeptides were obtained by in vitro O-glycosylation reaction using microsomal preparations of murine thymocytes, human gastric fundus and colonic mucosa. ELISA assays were performed with peroxidase-labeled murine monoclonal IgG2, kappa light chain (5D4) antibodies against ALL. Among the in vitro neoglycopeptides, only those of TTSAPTTS containing GalNAc at Thr in #2 and #6 reacted with ALL. Neither the TTSAPTTS glycopeptide, containing a unique GalNAc residue at Thr in #2, nor others (with more than two GalNAc residues) interacted with the lectin. Computational docking assays of the lower energy conformers for interactions between glycopeptides and lectins confirmed that ALL recognized GalNAc residues when they are spaced out in glycan structures, whereas GalNAc residues arranged in clusters prevented interaction with the lectin, indicating that ALL is specific for a special GalNAc-containing motif found in different O-glycoproteins.
authors.affiliation: Departamento de Bioquímica, Instituto Nacional de Enfermedades Respiratorias, Tlalpan, DF, 14080, Mexico.
authors.forename: Pedro
authors.initials: P
authors.lastname: Hernández
authors.forename: Daniel
authors.initials: D
authors.lastname: Tetaert
authors.forename: Gérard
authors.initials: G
authors.lastname: Vergoten
authors.forename: Henri
authors.initials: H
authors.lastname: Debray
authors.forename: Maria
authors.initials: M
authors.lastname: del Carmen Jimenez
authors.forename: Georgina
authors.initials: G
authors.lastname: Fernández
authors.forename: Concepción
authors.initials: C
authors.lastname: Agundis
authors.forename: Pierre
authors.initials: P
authors.lastname: Degand
authors.forename: Edgar
authors.initials: E
authors.lastname: Zenteno
mesh_terms: D000116:Acetylgalactosamine / Q000737:chemistry; D027721:Amaranthus; D000595:Amino Acid Sequence; D000818:Animals; D019075:Electrophoresis, Capillary; D005260:Female; D006020:Glycopeptides / Q000737:chemistry* / Q000378:metabolism; D006023:Glycoproteins / Q000737:chemistry*; D006031:Glycosylation; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008861:Microsomes / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D037121:Plant Lectins / Q000737:chemistry*; D011487:Protein Conformation; D013050:Spectrometry, Fluorescence; D013950:Thymus Gland / Q000378:metabolism
chemical_list: C121359:Amaranthus leucocarpus lectin; D006020:Glycopeptides; D006023:Glycoproteins; D037121:Plant Lectins; D000116:Acetylgalactosamine