Evidence for boundary lipid in membranes
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Date
1973-02
Authors
Jost, P. C.
Griffith, O. H.
Capaldi, R. A.
Vanderkooi, G.
Journal Title
Journal ISSN
Volume Title
Publisher
Proceedings of the National Academy of Sciences
Abstract
ABSTH\OT (Mochromc oxidase (EC 1.9.3.1) isolated from
hccf-hcarl mitochondria with an appropriate phospholipid
content forms vesicular structures. Lipid-protein interactions in this model membrane system were studied with
the,lipid spin label, 16-doxylstearic acid. As the phospholipid/
prolein ratio is varied, two spectral components are
ohserved. Al low phospholipid/prolcin ratios (<0.19 mg of
phospholipid per mg of protein) the lipid spin label is
liifCll!) immobilized. At higher phospholipid content an
additional component characteristic of fluid lipid hilayers
is evideiil. By summation of digilalized spectra and subsequent
integration it was shown that all composite spec
tra could he approximated by assuming only two com
ponents arc present, and that the amount of phospholipid
hound In Ihr protein is independent of the extent of the
fluid hilaw-r region. The experimentally determined
amount of phospholipid for maximum occupancy of pro-
Iciii-hound niies is ahouI 0.2 mg of phospholipid per 1.0
nig itl protein. Iialiulalions show that this ralio is con
sistent with a single layerof phospholipid surrounding the
protein complex. The data are interpreted as evidence for
a boundary of immobilized lipid between the hydrophobic
protein and adjacent fluid hilayer regions in this membrane model system.
Description
6 pages
Keywords
Citation
Jost, P. C., Griffith, O. H., Capaldi, R. A. & Vanderkooi, G. (1973) Evidence for boundary lipid in membranes. Proc. Natl. Acad. Sci. USA 70, 480‑484.