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Molecular Sieving with PEGylated Dendron-Protein Conjugates
Billy Deng1, Evan Burns1, Stuart A McNelles1
1Department of Chemistry and Chemical Biology, McMaster University, Hamilton, Ontario L8S 4M1, Canada.
Bioconjugate Chemistry
|July 27, 2023
Summary
New dendron-protein conjugates using bis-MPA scaffolds were created. These modified enzymes retained activity with small molecules but showed reduced activity with larger proteins, demonstrating size-selective enzyme modification.
Area of Science:
- Bioconjugation Chemistry
- Enzyme Engineering
- Materials Science
Background:
- Enzyme modification is crucial for tailoring protein function.
- Dendrimers offer precise control over molecular architecture.
- Poly(ethylene glycol) (PEG)ylation enhances protein stability and solubility.
Purpose of the Study:
- To synthesize novel dendron-protein conjugates using bis-MPA dendrons and α-chymotrypsin (α-CT).
- To investigate the impact of dendron generation and PEG length on enzyme activity and substrate selectivity.
- To evaluate the potential of these conjugates for size-selective biocatalysis.
Main Methods:
- Synthesis of generation 3-5 dendrons with varying PEG lengths and a dibenzocyclooctyne core.
- Attachment of dendrons to azide-decorated α-CT via strain-promoted azide-alkyne cycloaddition.
- Characterization using FT-IR, NMR spectroscopy, and cryo-electron microscopy.
- Enzyme activity assays using small molecule and protein substrates (casein, BSA).
Main Results:
- Dendron-α-CT conjugates were successfully synthesized and characterized.
- Enzyme activity was largely retained for small molecule substrates.
- Activity towards larger protein substrates was significantly reduced, indicating a sieving effect.
- PEG chain length had a greater impact on enzyme activity than dendron generation.
Conclusions:
- The synthesized dendron-protein conjugates exhibit size-selective activity.
- G3-PEG2000, G4-PEG2000, and G5-PEG1000 conjugates showed the highest sieving ratios.
- These conjugates offer a promising platform for developing enzymes with tailored substrate specificity.
