Carbohydrate-lectin interactions assayed by SPR

Area of Science:

• Carbohydrate Chemistry
• Biophysical Chemistry
• Protein-Ligand Interactions

Background:

• Surface plasmon resonance (SPR) is a label-free technique for studying molecular interactions.
• Lectins are proteins that bind carbohydrates, playing roles in biological recognition.
• Avidity effects from multiple binding sites on lectins can complicate affinity measurements.

Purpose of the Study:

• To optimize surface plasmon resonance (SPR) methods for determining lectin-glycoconjugate binding affinities.
• To address challenges posed by lectin avidity and analyte heterogeneity in SPR.
• To establish reproducible protocols for lectin-ligand interaction analysis.

Main Methods:

• Immobilizing lectins onto sensor chips and using soluble glycoconjugates as analytes.
• Employing the Sips approach for heterogeneous glycoconjugates and oligosaccharide mixtures.
• Utilizing an inhibition assay with neoglycoproteins and small oligosaccharides.
• Direct binding measurements for larger glycoconjugates like peptide-glycocluster conjugates.
• Using simple sugars for sensor chip regeneration to maintain lectin stability.

Main Results:

• Reproducible and accurate affinity data were obtained when lectins were immobilized.
• The Sips approach provided reliable mean binding constants for heterogeneous ligands.
• Inhibition assays effectively determined binding constants for small oligosaccharides.
• Direct measurements were suitable for larger glycoconjugates.
• Simple sugars enabled efficient sensor chip cleaning and prolonged lectin stability.

Conclusions:

• Optimized SPR protocols, including immobilization strategies and specific analytical methods, enable accurate lectin-glycoconjugate affinity determination.
• Careful experimental design is crucial to mitigate avidity effects and ensure data reliability.
• The use of simple sugars for regeneration offers a practical and gentle method for sensor chip maintenance.