Affinity determination of ricinus communis agglutinin ligands identified from combinatorial O- and S-,N-glycopeptide libraries.
Two combinatorial glycopeptide libraries were synthesized on solid support via the "split-and-mix" method combined with the ladder synthesis strategy. The O-glycopeptide library contained Gal(beta1-O)Thr, whereas the S-,N-glycopeptide library contained both Gal(beta1-S)Cys and Gal(beta1-N)Asn. In this model study, the two libraries were screened against the fluorescently labeled lectin Ricinus communis agglutinin (RCA120). The screening results showed that both O- and S- or S-,N-glycopeptides were recognized by the lectin with similar amino acid recognition patterns. Surface plasmon resonance interaction studies demonstrated that both the selected S- or S-,N-glycopeptide hits and the O-glycopeptides bound to the lectin with a similar affinity. Structure 19, containing two glycosylated cysteine residues, bound to the receptor with the highest affinity (KA = 3.81 x 10(4) M(-1)), which is comparable to N-acetyllactosamine. Competition assays, in which some selected glycopeptides and methyl beta-d-galactopyranoside competed for the binding site of immobilized RCA120, showed that the glycopeptide-lectin interaction was carbohydrate-specific. Incubation of the O- and S-,N-glycopeptides with beta-galactosidase demonstrated the complete stability of S-,N-glycopeptides toward enzymatic degradation, whereas O-glycopeptides were not completely stable.
Maljaars
C Elizabeth P
CE
Bijvoet Center, Department of Bio-Organic Chemistry, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands.
Halkes
Koen M
KM
de Oude
Willem L
WL
Haseley
Simon R
SR
Upton
Peter J
PJ
McDonnell
Martin B
MB
Kamerling
Johannis P
JP
D002846:Chromatography, Affinity / Q000379:methods*; D020650:Combinatorial Chemistry Techniques / Q000379:methods*; D006020:Glycopeptides / Q000138:chemical synthesis / Q000737:chemistry*; D008024:Ligands; D015394:Molecular Structure; D019151:Peptide Library; D037121:Plant Lectins / Q000737:chemistry*; D012680:Sensitivity and Specificity; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods; D013329:Structure-Activity Relationship; D020349:Surface Plasmon Resonance / Q000379:methods; D013997:Time Factors
D006020:Glycopeptides; D008024:Ligands; D019151:Peptide Library; D037121:Plant Lectins; C017707:Ricinus communis agglutinin-1