Lipid bilayer perturbations induced by simple hydrophobic peptides

Journal Article · Tue Sep 22 04:00:00 EDT 1987 · Biochemistry; (United States)

DOI:https://doi.org/10.1021/bi00393a027· OSTI ID:5559787

Jacobs, R E; White, S H

Mixtures of tripeptides of the form Ala-X-Ala-O-tert-butyl with 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) bilayers have been used as a model system for studying the influence of hydrophobic peptides on membrane order and dynamic properties by means of deuterium NMR spectroscopy. Tripeptides with X = Ala, Leu, Phe, and Trp have been examined. Lipid /sup 2/H NMR spectra of acyl chain perdeuteriated DMPC ((/sup 2/H/sub 54/)DMPC) show that the addition of peptide disorders the bilayer lipid acyl chains and that the extent of the perturbation increases as the size of the central residue increases. Moment analyses of the spectra indicate that, while the average acyl chain order parameter decreases with increasing central residue size, the order parameter spread across the bilayer (the mean-squared width of the distribution) increases. Lipid segmental /sup 2/H longitudinal relaxation rates, 1/T/sub 1/(i), exhibit a square-law functional dependence on S/sub CD/(i) both with and without the addition of peptide. The addition of peptide causes an increase in the slope of plots of 1/T/sub 1/(i) vs. absolute value S/sub CD/(i)/sub 2/ with little change in the 1/T/sub 1/(i) intercept, indicating a complex modulation of the acyl chain motions. /sup 2/H NMR spectra of Ala-(/sup 2/H/sub 4/)Ala-Ala-O-tert-butyl in DMPC bilayers have both isotropic and powder pattern components that vary as a function of temperature. At 30/sup 0/C the /sup 2/H spin-lattice relaxation time for the labeled Ala residue increase in going from bilayer-incorporated peptide to polycrystalline peptide to polycrystalline Ala x HCl. These experiments provide no information on the location of these peptides in the bilayer. If they protrude into the hydrocarbon core, their disordering influence can be attributed to a direct disruption of acyl chain packing.

• Research Organization: Univ. of California, Irvine
• OSTI ID: 5559787
• Journal Information: Biochemistry; (United States), Journal Name: Biochemistry; (United States) Vol. 26:19; ISSN BICHA
• Country of Publication: United States
• Language: English

Related Subjects

550601* -- Medicine-- Unsealed Radionuclides in Diagnostics
62 RADIOLOGY AND NUCLEAR MEDICINE
ALANINES
AMINO ACIDS
BIOCHEMISTRY
CARBOXYLIC ACIDS
CHEMISTRY
CONFORMATIONAL CHANGES
DEUTERIUM
ESTERS
HYDROGEN ISOTOPES
ISOTOPES
LIGHT NUCLEI
LIPIDS
MAGNETIC RESONANCE
MEMBRANES
NMR SPECTRA
NUCLEAR MAGNETIC RESONANCE
NUCLEI
ODD-ODD NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC PHOSPHORUS COMPOUNDS
PEPTIDES
PHOSPHOLIPIDS
PROTEINS
RELAXATION
RESONANCE
SPECTRA
SPIN-LATTICE RELAXATION
STABLE ISOTOPES
TEMPERATURE DEPENDENCE