Using O-2 to determine membrane immersion depth in bilayers by F-19 NMR a solid state and high-resolution NMR approach
Biophysics
Prosser R S; Luchette P A; Westerman P W; Rozek A; Hancock R E W
Biophysical Journal
2001
2001-01
Journal Article
n/a
Probing immersion depth & topology of membrane proteins by NMR. An ode to O-2
Biophysics
Prosser R S; Luchette P A; Westerman P W; Rozek A; Hancock R E W
Biophysical Journal
2001
2001-01
Journal Article
n/a
Interaction of protoporphyrin IX with magnetically aligned phospholipid bilayer membranes: A H-2 NMR study
Biophysics
Prosser R S; Shiyanovskaya I V; Malmer M; Westerman P W
Biophysical Journal
2001
2001-01
Journal Article
n/a
Determination of membrane immersion depth with O-2: A high-pressure F-19 NMR study
Biophysics; cholesterol; conformational-changes; dynamics; lipid bilayers; micelles; nuclear magnetic-resonance; phospholipid-bilayers; protein-structure; solid-state nmr; x-ray-diffraction
Oxygen is known to partition with an increasing concentration gradient toward the hydrophobic membrane interior. At partial pressures (P-O2) of 100 Atm or more, this concentration gradient is sufficient to induce paramagnetic effects that depend sensitively on membrane immersion depth. This effect is demonstrated for the fluorine nucleus by depth-dependent: paramagnetic shifts and spin-lattice relaxation rates, using a fluorinated detergent, CF3(CF2)(5)C2H4-O-maltose (TFOM), reconstituted into a lipid bilayer model membrane system, To interpret the spin-lattice relaxation rates (R-1(P)) in terms of a precise immersion depth, two specifically fluorinated cholesterol species (6-fluorocholesterol and 25-fluorocholesterol), whose membrane immersion depths were independently estimated, were studied by F-19 NMR. The paramagnetic relaxation rates, R-1(P), of the cholesterol species were then used to parameterize a Gaussian profile that directly relates R-1(P) to immersion depth z.: This same Gaussian curve could then be used to determine the membrane immersion depth of all six fluorinated chain positions of TFOM and of two adjacent residues of specifically fluorinated analogs of the antibacterial peptide indolicidin. The potential of this method for determination of immersion depth and topology of membrane proteins is discussed.
Prosser R S; Luchette P A; Westerman P W; Rozek A; Hancock R E W
Biophysical Journal
2001
2001-03
Journal Article
<a href="http://doi.org/10.1016/s0006-3495(01)76113-9" target="_blank" rel="noreferrer noopener">10.1016/s0006-3495(01)76113-9</a>
Using O2 to probe membrane immersion depth by 19F NMR.
*Hydrocarbons; *Oxygen; Biological; Cyclic N-Oxides; Dimyristoylphosphatidylcholine/*chemistry; Fluorinated; Fluorine; Lipid Bilayers/*chemistry; Magnetic Resonance Spectroscopy/*methods; Maltose/*analogs & derivatives; Models; Phospholipid Ethers/*chemistry; Pressure; Spin Labels
A fluorinated detergent, CF(3)(CF(2))(5)C(2)H(4)-O-maltose, was reconstituted into a lipid bilayer model membrane system to demonstrate the feasibility of determining solvent accessibility and membrane immersion depth of each fluorinated group by (19)F NMR. Apolar oxygen, which is known to partition with an increasing concentration gradient toward the hydrophobic membrane interior, exhibits a range of paramagnetic relaxation effects on (19)F nuclei, depending on its depth in the membrane. This effect, which is predominately associated with spin-lattice relaxation rates (R(1)) and chemical shifts, can be amplified greatly with minimal line broadening by increasing the partial pressure of O(2) at least 100-fold (i.e., P(O(2)) greater than 20 bar). The differences of longitudinal relaxation rates at 20 bar of oxygen pressure to those under ambient pressure (R(1)(20bar) - R(1)(0)) are largest for those fluorine groups expected to be most deeply buried in the membrane bilayer. This result contrasts with the reverse trend, which is observed on addition of a membrane surface-associated paramagnetic species, 4-(N,N-dimethyl-N-hexadecyl) ammonium-2,2,6,6-tetramethylpiperidine-1-oxyl iodide (CAT-16) at ambient pressures. Thus, differential relaxation rates may be observed in (19)F-labeled membrane-associated molecules resulting from the addition of apolar oxygen under high pressure. The results demonstrate that the degree of solvent accessibility and membrane immersion depth of specific fluorinated species in membrane-associated macromolecules can be probed by (19)F NMR.
Prosser R S; Luchette P A; Westerman P W
Proceedings of the National Academy of Sciences of the United States of America
2000
2000-08
Article information provided for research and reference use only. All rights are retained by the journal listed under publisher and/or the creator(s).
<a href="http://doi.org/10.1073/pnas.170295297" target="_blank" rel="noreferrer noopener">10.1073/pnas.170295297</a>