High affinity heparan sulfate binding peptides for diagnostic and therapeutic applications

Overview

This research programme focuses on the design, selection, and optimisation of high-affinity heparan sulfate (HS) binding peptides derived from fibroblast growth factor (FGF) binding sites. HS is a complex glycosaminoglycan found on cell surfaces and in the extracellular matrix, playing critical roles in cell signalling, growth factor regulation, and tissue development. The peptides are engineered to achieve binding affinities in the range of 10⁻⁵ to 10⁻⁷ M, making them suitable for a range of biomedical applications including diagnostic imaging, particularly positron emission tomography (PET), and potential therapeutic targeting.

The approach leverages a comprehensive bioinformatics analysis of over 400 HS-binding proteins to identify optimal amino acid sequences. By introducing strategic substitutions of arginine and lysine residues alongside hydrogen-bonding and non-polar residues with appropriate spacing, the team can systematically improve binding affinity through iterative design and testing cycles.

Technical specifications

Key features:

• Peptides derived from high-affinity FGF binding sites with starting affinities of approximately 30 µM
• Optimisation through amino acid substitution cycles introducing Arg and Lys residues flanked by hydrogen-bonding (Gln, Asn) and non-polar residues
• Both L- and D-amino acid peptide variants designed; D-peptides offer enhanced stability
• Peptide molecular weight under 1000 Da for efficient synthesis and modification
• Compatibility with modifications for PET imaging applications
• High-throughput binding analysis using Octet biosensor with HS analogue-functionalised sensors
• HS structural requirements determined using a library of systematically modified HS analogue saccharides
• Characterisation via isothermal titration calorimetry (ITC) and confocal microscopy in cell lines
• Two rounds of design and testing yielding approximately 20 peptides with varied binding affinities

Technology readiness level

The research is currently at an advanced preclinical stage. The team has established detailed binding site characterisation and GAG-binding preferences for most FGFs through prior published studies. The bioinformatics foundation, based on analysis of over 400 HS binding partners, provides a robust predictive framework for peptide design. Future validation will involve two complete rounds of peptide design, synthesis, and high-throughput binding assessment, with comprehensive characterisation including thermodynamic analysis and cellular imaging. The programme aims to deliver a panel of approximately 20 optimised peptides with well-characterised binding profiles and defined HS structural requirements, ready for further development toward diagnostic and therapeutic applications.