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Interaction of recombinant interleukin-2 with liposomal bilayers
F J Koppenhagen1, A J Visser, J N Herron
1Department of Pharmaceutics, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, 3508 TB Utrecht, The Netherlands. koppenhagen@clara.net
Journal of Pharmaceutical Sciences
|June 11, 1998
Summary
Recombinant interleukin-2 (rIL-2) liposome interactions were studied. Adsorption to liposomes enhances rIL-2 fluorescence by reducing intramolecular quenching, without altering protein secondary structure.
Area of Science:
- Biochemistry
- Biophysics
- Immunology
Background:
- Liposomes are utilized as drug delivery vehicles for cancer immunotherapy.
- Recombinant interleukin-2 (rIL-2) is a key immunotherapeutic agent.
Purpose of the Study:
- To investigate the structural effects of rIL-2 adsorption onto liposomal membranes.
- To understand the biophysical changes in rIL-2 upon interaction with liposomes.
Main Methods:
- Polarized fluorescence decay studies were used to analyze tryptophan fluorescence.
- Circular dichroism (CD) spectroscopy assessed protein secondary structure.
- Fluorescence anisotropy decay experiments examined protein aggregation.
Main Results:
- rIL-2 readily adsorbs to liposomal membranes.
- Adsorption significantly increased rIL-2 fluorescence intensity (2-fold) and tryptophan susceptibility to iodide quenching.
- No significant changes in rIL-2 secondary structure were observed via CD.
- Protein self-aggregation was noted under low ionic strength conditions.
Conclusions:
- Liposome adsorption abrogates intramolecular quenching in rIL-2, leading to enhanced fluorescence.
- The protein's secondary structure remains largely intact upon liposome interaction.
- These findings provide insights into rIL-2 liposome complex formation for immunotherapy.