Interaction of melittin with phosphatidylcholine membranes. Binding isotherm and lipid head-group conformation

Journal Article · Tue May 16 04:00:00 EDT 1989 · Biochemistry; (USA)

DOI:https://doi.org/10.1021/bi00436a014· OSTI ID:5442588

Kuchinka, E; Seelig, J ^[1]

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1. Univ. of Basel (Switzerland)

The binding of melittin to nonsonicated bilayer membranes composed of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine was studied with an ultracentrifugation assay and with {sup 2}H and {sup 31}P nuclear magnetic resonance. Melittin binding could best be described by a partition equilibrium with K{sub p} = (2.1 {plus minus} 0.2) {times} 10{sup 3} M{sup {minus}1}, measuring the binding isotherm in the concentration range of 0-100 {mu}M melittin and taking into account electrostatic effects by means of the Gouy-Chapman theory. This partition coefficient is smaller than that deduced for small sonicated vesicles and attests to the tighter lipid packing in the nonsonicated bilayers. Deuterium magnetic resonance revealed a conformational change of the phosphocholine head group upon melittin binding. The quadrupole splittings of the {alpha} and {beta} segments of the choline head group varied linearly with the amount of bound melittin but in opposite directions; i.e., the {alpha} splitting decreased, and the {beta} splitting increased. This conformational change is not specific to melittin but is a response of the phosphocholine head group to positive membrane surface charges in general. Quantitatively, melittin is one of the most efficient head-group modulators, the efficiency per unit charge comparable to that of charged local anesthetics or hydrophobic ions.

• OSTI ID: 5442588
• Journal Information: Biochemistry; (USA), Journal Name: Biochemistry; (USA) Vol. 28:10; ISSN 0006-2960; ISSN BICHA
• Country of Publication: United States
• Language: English

Related Subjects

550601* -- Medicine-- Unsealed Radionuclides in Diagnostics
62 RADIOLOGY AND NUCLEAR MEDICINE
CARBOXYLIC ACIDS
CELL CONSTITUENTS
CELL MEMBRANES
CENTRIFUGATION
CHEMICAL REACTIONS
CONFORMATIONAL CHANGES
CROSS-LINKING
DEUTERIUM COMPOUNDS
ESTERS
HYDROGEN COMPOUNDS
ISOTHERMS
ISOTOPES
LIGHT NUCLEI
LIPIDS
MAGNETIC RESONANCE
MELLITIC ACID
MEMBRANES
NMR SPECTRA
NUCLEAR MAGNETIC RESONANCE
NUCLEI
ODD-EVEN NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC PHOSPHORUS COMPOUNDS
PEPTIDES
PHOSPHOLIPIDS
PHOSPHORUS 31
PHOSPHORUS ISOTOPES
POLYMERIZATION
PROTEINS
RESONANCE
SEPARATION PROCESSES
SPECTRA
STABLE ISOTOPES
ULTRACENTRIFUGATION