Exploring Glycan Binding Specificity of Odorranalectin by Alanine Scanning Library

Area of Science:

• Biochemistry
• Carbohydrate Chemistry
• Molecular Recognition

Background:

• Odorranalectin (OL) is a cyclic peptide with lectin-like properties.
• Understanding carbohydrate-peptide interactions is crucial for biological processes.

Purpose of the Study:

• To identify key amino acid residues in odorranalectin responsible for binding to specific monosaccharides.
• To investigate the binding affinities and thermodynamic properties of modified odorranalectin analogues.

Main Methods:

• Fluorescently labelled alanine scan analogues of odorranalectin were synthesized.
• Enzyme-linked lectin assay (ELLA) was used to screen binding to BSA-conjugated monosaccharides.
• Isothermal titration calorimetry (ITC) evaluated the thermodynamics of binding.

Main Results:

• Lys5, Phe7, Tyr9, Gly12, Leu14, and Thr17 were identified as crucial for binding BSA-L-fucose, BSA-D-galactose, and BSA-N-acetyl-D-galactosamine.
• Alanine substitutions at Ser3, Pro4, and Val13 enhanced binding affinity.
• Arg8 was important for differentiating binding between L-fucose/D-galactose and N-acetyl-D-galactosamine.
• Binding affinities varied for MUC1 glycopeptide, asialofetuin, and fucoidan.
• Thermodynamic profiles indicated entropy-driven binding for asialofetuin and enthalpy-entropy compensation for fucoidan.

Conclusions:

• Specific residues in odorranalectin are critical for carbohydrate recognition.
• Alanine scanning is an effective method for optimizing lectin-like peptide binding.
• Thermodynamic analysis provides insights into the mechanisms of carbohydrate-lectin interactions.