Melittin binding to mixed phosphatidylglycerol/phosphatidylcholine membranes

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Melittin binding to mixed phosphatidylglycerol/phosphatidylcholine membranes

JournalArticle (Originalarbeit in einer wissenschaftlichen Zeitschrift)

ID	153050
Author(s)	Seelig, J.
Author(s) at UniBasel	Seelig, Joachim
Year	1990
Title	Melittin binding to mixed phosphatidylglycerol/phosphatidylcholine membranes
Journal	Biochemistry
Volume	29
Number	1
Pages / Article-Number	52-8
Keywords	Bee Venoms/metabolism; Choline/metabolism; Circular Dichroism; Deuterium/diagnostic use; Electrochemistry; Magnetic Resonance Spectroscopy/methods; Melitten/metabolism; Membrane Lipids/metabolism; Membranes; Artificial; Phosphatidylcholines/metabolism; Phosphatidylglycerols/*metabolism; Protein Binding; Protein Conformation
Abstract	The binding of bee venom melittin to negatively charged unilamellar vesicles and planar lipid bilayers composed of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) and 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoglycerol (POPG) was studied with circular dichroism and deuterium NMR spectroscopy. The melittin binding isotherm was measured for small unilamellar vesicles containing 10 or 20 mol % POPG. Due to electrostatic attraction, binding of the positively charged melittin was much enhanced as compared to the binding to neutral lipid vesicles. However, after correction for electrostatic effects by means of the Gouy-Chapman theory, all melittin binding isotherms could be described by a partition Kp = (4.5 +/- 0.6) x 10(4) M-1. It was estimated that about 50% of the total melittin surface was embedded in a hydrophobic environment. The melittin partition constant for small unilamellar vesicles was by a factor of 20 larger than that of planar bilayers and attests to the tighter lipid packing in the nonsonicated bilayers. Deuterium NMR studies were performed with coarse lipid dispersions. Binding of melittin to POPC/POPG (80/20 mol/mol) membranes caused systematic changes in the conformation of the phosphocholine and phosphoglycerol head groups which were ascribed to the influence of electrostatic charge on the choline dipole. While the negative charge of phosphatidylglycerol moved the N+ end of the choline -P-N+ dipole toward the bilayer interior, the binding of melittin reversed this effect and rotated the N+ end toward the aqueous phase. No specific melittin-POPG complexes could be detected. The phosphoglycerol head group was less affected by melittin binding than its choline counterpart.
Publisher	American Chemical Society
ISSN/ISBN	0006-2960
edoc-URL	http://edoc.unibas.ch/dok/A5257470
Full Text on edoc	No
Digital Object Identifier DOI	10.1021/bi00453a007
PubMed ID	http://www.ncbi.nlm.nih.gov/pubmed/2322549
ISI-Number	WOS:A1990CH52900007
Document type (ISI)	Journal Article

02/05/2024

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