Influence of microenvironment and liposomal formulation on secondary structure and bilayer interaction of lysozyme

The conformation of peptide and protein drugs in various microenvironments and the interaction with drug carriers such as liposomes are of considerable interest. In this study the influence of microenvironments such as pH, salt concentration, and surface charge on the secondary structure of a model...

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Bibliographic Details
Published in:Colloids and surfaces, B, Biointerfaces B, Biointerfaces, 2010-02, Vol.75 (2), p.501-509
Main Authors: Witoonsaridsilp, Wasu, Panyarachun, Busaba, Sarisuta, Narong, Müller-Goymann, Christel C.
Format: Article
Language:English
Subjects:
Animals
Buffers
Charged liposomes
Chickens
Cholesterol - chemistry
Circular Dichroism
Conformation
Lipid Bilayers - chemistry
Liposomes - chemistry
Lysozyme
Magnetic Resonance Spectroscopy
Muramidase - chemistry
Muramidase - metabolism
Particle Size
Phosphatidylcholines - chemistry
Protein Structure, Secondary
Protein–lipid binding
Secondary structure
Solutions
Spectroscopy, Fourier Transform Infrared
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Summary:The conformation of peptide and protein drugs in various microenvironments and the interaction with drug carriers such as liposomes are of considerable interest. In this study the influence of microenvironments such as pH, salt concentration, and surface charge on the secondary structure of a model protein, lysozyme, either in solution or entrapped in liposomes with various molar ratios of phosphatidylcholine (PC):cholesterol (Chol) was investigated. It was found that entrapment efficiency was more pronounced in negatively charged liposomes than in non-charged liposomes, which was independent of Chol content and pH of hydration medium. The occurrence of aggregation, decrease in zeta potential, and alteration of 31P NMR chemical shift of negatively charged lysozyme liposomes compared to blank liposomes suggested that the electrostatic interaction plays a major role in protein–lipid binding. Addition of sodium chloride could impair the neutralizing ability of positively charged lysozyme on negatively charged membrane via chloride counterion binding. Neither lysozyme in various buffer solutions with sodium chloride nor that entrapped in liposomes showed any significant change in their secondary structures. However, significant decrease in α-helical content of lysozyme in non-charged liposomes at higher pH and salt concentrations was discovered.
ISSN:0927-7765
1873-4367
DOI:10.1016/j.colsurfb.2009.09.027