Integral membrane proteins significantly decrease the molecular motion in lipid bilayers: a deuteron NMR relaxation study of membranes containing myelin proteolipid apoprotein
The influence of the myelin proteolipid apoprotein on lipid chain order and dynamics was studied by /sup 2/H NMR of membranes reconstituted with specifically deuterated dimyristoyl phosphatidylcholines. Quadrupolar echo and saturation recovery experiments were fitted by numerical solution of the stochastic Liouville equation, using a model that includes both inter- and intramolecular motions. Combined simulations of both the relaxation times and the quadrupolar echo line shapes as a function of pulse spacing allowed unambiguous assignment of the various motional modes and a consistent interpretation of data from lipids labeled on the C-6, C-13, and C-14 positions of the sn-2 chain. In the fluid phase, the protein has little influence on either the chain order or the population of gauche rotational isomers but strongly retards the chain dynamics. For 1-myristoyl-2-(13-/sup 2/H/sub 2/) myristoyl-sn-glycero-3-phosphocholine at 35/sup 0/C, the correlation time for chain fluctuation increases for 20 nsec to 650 nsec and for chain rotation from 10 nsec to 180 nsec, and the gauche isomer lifetime increases from 0.15 nsec to 1.75 nsec, on going from the lipid alone to a recombinant of protein/lipid ratio 0.073 mol/mol. The results are essentially consistent with spin-label ESR studies on the same system, when allowance is made for the different time scales of the two spectroscopies.
- Research Organization:
- Institut fuer Physikalische Chemie der Universitaet Stuttgart, Germany, F.R.
- OSTI ID:
- 5301231
- Journal Information:
- Proc. Natl. Acad. Sci. U.S.A.; (United States), Vol. 84:12
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
APOLIPOPROTEINS
NUCLEAR MAGNETIC RESONANCE
CELL MEMBRANES
MOLECULAR STRUCTURE
DEUTERIUM COMPOUNDS
ELECTRON SPIN RESONANCE
MYELIN
PHOSPHOLIPIDS
PROTONS
RELAXATION TIME
BARYONS
CELL CONSTITUENTS
ELEMENTARY PARTICLES
ESTERS
FERMIONS
HADRONS
HYDROGEN COMPOUNDS
LIPIDS
LIPOPROTEINS
MAGNETIC RESONANCE
MEMBRANES
NUCLEONS
ORGANIC COMPOUNDS
ORGANIC PHOSPHORUS COMPOUNDS
PROTEINS
RESONANCE
550601* - Medicine- Unsealed Radionuclides in Diagnostics