Specificity of Amaranthus leucocarpus syn. hypocondriacus lectin for O-glycopeptides.
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.
Hernández
Pedro
P
Departamento de Bioquímica, Instituto Nacional de Enfermedades Respiratorias, Tlalpan, DF, 14080, Mexico.
Tetaert
Daniel
D
Vergoten
Gérard
G
Debray
Henri
H
del Carmen Jimenez
Maria
M
Fernández
Georgina
G
Agundis
Concepción
C
Degand
Pierre
P
Zenteno
Edgar
E
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
C121359:Amaranthus leucocarpus lectin; D006020:Glycopeptides; D006023:Glycoproteins; D037121:Plant Lectins; D000116:Acetylgalactosamine