Melittin binding to mixed phosphatidylglycerol/phosphatidylcholine membranes

Journal Article · Tue Jan 09 00:00:00 EST 1990 · Biochemistry; (USA)

DOI:https://doi.org/10.1021/bi00453a007· OSTI ID:6949002

Beschiaschvili, G; Seelig, J ^[1]

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1. Univ. of Basel (Switzerland)

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.

• OSTI ID: 6949002
• Journal Information: Biochemistry; (USA), Vol. 29:1; ISSN 0006-2960
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
PHOSPHOLIPIDS
MOLECULAR STRUCTURE
VENOMS
BIOCHEMICAL REACTION KINETICS
BEES
BIOELECTRICITY
CHOLINE
DEUTERIUM
NUCLEAR MAGNETIC RESONANCE
PROTEIN STRUCTURE
TRACER TECHNIQUES
ALCOHOLS
AMINES
AMMONIUM COMPOUNDS
ANIMALS
ARTHROPODS
DRUGS
ELECTRICITY
ESTERS
HYDROGEN ISOTOPES
HYDROXY COMPOUNDS
HYMENOPTERA
INSECTS
INVERTEBRATES
ISOTOPE APPLICATIONS
ISOTOPES
KINETICS
LIGHT NUCLEI
LIPIDS
LIPOTROPIC FACTORS
MAGNETIC RESONANCE
NUCLEI
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
ORGANIC PHOSPHORUS COMPOUNDS
QUATERNARY COMPOUNDS
REACTION KINETICS
RESONANCE
STABLE ISOTOPES
550201* - Biochemistry- Tracer Techniques