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Polyethyleneimine-protein interactions and implications on protein stability.
Laura Mazzaferro1, Javier D Breccia, Maria M Andersson
1Depto. de Química, CONICET, FCEyN-Universidad Nacional de La Pampa (UNLPam), Av. Uruguay 151, 6300 Santa Rosa, La Pampa, Argentina.
International Journal of Biological Macromolecules
|April 27, 2010
Summary
Low molecular weight polyethyleneimine (PEI) impacts protein stability differently based on protein charge. While PEI (2000 Da) slightly destabilizes acidic proteins, it offers protection against oxidative stress for heart lactate dehydrogenase.
Area of Science:
- Biochemistry
- Polymer Science
Background:
- Protein stability is crucial for biological function and therapeutic applications.
- Polyethyleneimine (PEI) is a cationic polymer used in various applications, including gene delivery.
- Understanding PEI's interaction with proteins is essential for optimizing its use and predicting its effects.
Purpose of the Study:
- To investigate the effect of low molecular weight polyethyleneimine (PEI, 2000 Da) on the thermodynamic stability and secondary structure of seven model proteins.
- To explore the relationship between protein surface charge and PEI concentration in protein-polymer interactions.
- To assess PEI's protective effects against oxidative stress in a specific protein model.
Main Methods:
- Circular dichroism (CD) spectroscopy was used to monitor changes in protein melting temperature (T(m)) and secondary structure.
- Seven model proteins with varying isoelectric points (acidic and basic) were used.
- Protein surface charge density and PEI concentration were correlated with flocculation effects.
Main Results:
- PEI (2000 Da) did not significantly alter the T(m) of basic proteins but lowered the T(m) of acidic proteins.
- Secondary structures of basic proteins remained largely unchanged, while acidic proteins showed diminished CD spectra, attributed to phase separation.
- An inverse relationship was found between the surface charge density of acidic proteins and the PEI concentration required for maximum flocculation.
- PEI (2000 Da) demonstrated a protective effect on heart lactate dehydrogenase under increasing oxidative stress.
Conclusions:
- Low molecular weight PEI exhibits differential effects on protein stability, primarily impacting acidic proteins.
- Protein surface charge is a key determinant in PEI-induced protein aggregation and stability changes.
- Despite potential destabilization, PEI can confer protection against oxidative stress to certain proteins.
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