Griffith, O. Hayes H.

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Browsing Griffith, O. Hayes H. by Author "Jost, P. C."

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    Evidence for boundary lipid in membranes
    (Proceedings of the National Academy of Sciences, 1973-02) Jost, P. C.; Griffith, O. H.; Capaldi, R. A.; Vanderkooi, G.
    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.
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    Lipid binding to the amphipathic membrane protein cytochrome b5
    (Proceedings of the National Academy of Sciences, 1974-06) Dehlinger, P. J.; Jost, P. C.; Griffith, O. H.
    ABSTRACT The lipid hinding properties of the membrane protein cytochrome b:. (detergent-extracted from calf liver microsomal preparations) were characterized by studying the interaction of spin-labeled lipid,- (5-, 12-, and 16-doxylstcaric acid and 5- and 16-cloxylphosphatidylcholine, where cloxyl refers to the nitroxide moiety) with cytochrome b :, using electron "pin resonance spectroscopy. The intact cytochrome b, n1olec11lc immobilizes all of the lipid spin label,;, while the segment of cytochrome b, released by trypsin doei. not afTcct lipid mobility. The immobilization of lipid spin label,-; on the h) ·drophohic surface of intact cytochrome b:, is not appreciably altered by associating the protein with liposomc" · DHTcrcnccs in polarity of the lipid binding site" between c, ·tochromc b, and phospholipid vc,.icles were also ob,-cr\'ed. The lipid binding sites on cytochrome b.; arc hydrophobic by conventional criteria, but arc more polar than the interior of fluid phospholipid bilayers.
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    Lipid‑protein and lipid‑lipid interactions in cytochrome oxidase model membranes
    (Journal of Supramolecular Structure, 1973) Jost, P. C.; Capaldi, R. A.; Vanderkooi, G.; Griffith, O. H.
    Two lipid environments are dete cted in membranous cyto chrome oxidase , using spin labeling techniques. This model membrane system consists of closed vesicular membranes formed spontaneou sly when the mem hr,jlne protein is isolated with its accompanying phospholipids. The data show both an immobili zed componen t, which is constant in amount , and a fluid componen t. Based on spectral analysis, the interpretation is that the bound component repre sents a single layer of lipid immobilized on the surface of the protein between the hydrophobic protein complex and the adjacent fluid bilayer regions. Maximal enzyme activity of this functional protein complex is attained when all of the bound sites are occupied , and above this level additional phospholipid (bilayer) has little or no effect on the enzyme activity .
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    The potential role of photoelectron microscopy in the analysis of biological surfaces
    (Scanning Electron Microscopy, 1984-05-07) Griffith, O. H.; Nadakavukaren, K. K.; Jost, P. C.
    The photoelectric effect provides the basis for an imaging technique useful for the study of biological surfaces. The photoelectron microscope (PEM) employs a UV lamp to photoeject electrons from the specimen surface. The electrons are then accelerated and imaged using electron optics. Photoelectron micrographs often resemble scanning electron micrographs, but the origin of contrast is different and these two techniques are complementary. Scanning Electron Microscopy (SEM) is unsurpassed in applications where specimens have pronounced relief or where elemental analysis is required. The advantages of PEM are a new origin of contrast, high sensitivity to fine topographical detail, short depth of information, and low specimen conductivity requirements. Photoelectron Images of model systems, cell surfaces and cytoskeletal elements have been obtained.
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