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T G Frey

Publications and source records attributed to T G Frey.

27 records · Page 2Linked to original sources
PubMed1984

Selective contrast in electron microscopy of crystalline cytochrome oxidase.

We have used various techniques for preparation of specimens for electron microscopy in order to selectively contrast different regions of vesicle crystals of cytochrome c oxidase dimers. The results are consistent with a dimer composed of two y-shaped monomers [Fuller et al., J. Mol. Biol. 134 (1979) 305] aligned along one pair of arms with the other pair of arms approximately 70 A apart. The four arms of the monomers lie within and perpendicular to the lipid bilayer in which the dimer is embedded, and the arms protrude approximately 25 A from the lipid bilayer on the matrix side of the membrane. The cytoplasmic side domains of the two monomers split away from one another forming a large cleft in the dimer. Monovalent antibodies (Fab fragments) to subunit IV appear to bind to the two monomer arms which are closely apposed across the two-fold axis of the dimer.

Crystallography↗
PubMed1982

Spatial relationship between cytochrome a and a3.

We have studied the spatial relationship between cytochromes a and a3 by the enhancement of the spin relaxation of cytochrome a3-NO EPR signals by the paramagnetic a heme at 15 K. An Fe-Fe distance of 12-19A is estimated from the absence of dipolar broadening and from the observation of spin relaxation enhancement in the a3-NO complex. When this result is combined with resonance x-ray diffraction data reported by Blasie et al. (Blasie, J. K., Pachence, J. M., Tavormina, A., Dutton, P. L., Stamatoff, J., Eisenberger, P., and Brown, G. (1982) Biochim. Biophys. Acta 679, 188-197) and the contribution from the exchange interaction is considered, we can limit the iron-iron distance to 12-16 A and estimate the angle between the Fe-Fe vector and mitochondrial membrane normal as 30-60 degrees. We also consider the possible effects of CuA on cytochrome a3-NO.

Anaerobiosis↗
PubMed1979

Gene 24-controlled osmotic shock resistance in bacteriophage T4: probable multiple gene functions.

By use of mixed infections with conditional lethal mutations in the head genes and an osmotic shock-resistant mutant we have demonstrated that osmotic shock resistance is controlled by gene 24. Using acrylamide gel electrophoresis combined with the "immune replicate" technique, we confirmed the positions of gene products 24 and 24* (P24 and P24*). In this paper we have still used the notation "P24," etc., for designating the product of gene 23, etc., although we prefer and use in general the designation "gp23" as introduced by Casjens and King (Annu. Rev. Biochem. 44:585, 1975). The reason for using the old notation is because the illustrations were prepared several years ago.) P24 ts showed a significantly slower mobility. Both osmotic shock-resistant and -sensitive mature phages contain 24*. Giants constructed with the Osr phage showed the same surface lattice as normal phage. Through temperature-shift experiments with 24(tsL90) alone and in combinations, we studied the phages which are matured after the shift to permissive temperature in the absence of new protein synthesis. Our results strongly suggest that only a fraction of the total phage complement of gene 24-controlled proteins is involved in determining the phenotype of shock resistance, and the remainder is necessary to mature the head.

Coliphages↗
PubMed1978

Structure and orientation of cytochrome c oxidase in crystalline membranes. Studies by electron microscopy and by labeling with subunit-specific antibodies.

The structure and the orientation of cytochrome c oxidase molecules in crystalline cytochrome c oxidase membranes (Vanderkooi, G., Senior, A.E., Capaldi, R.A., and Hayashi, H. (1972) Biochim. Biophys. Acta 274, 38-48) were studied by image analysis of electron micrographs and by reacting the crystalline preparations with immune gamma-globulins against individual cytochrome c oxidase subunits. Binding of gamma-globulins to the membranes was detected by the following two methods: (a) electrophoretic identification of gamma-globulin polypeptides in the washed membranes; (b) electron microscopic examination of the negatively stained membranes. The membranes bound immune gamma-globulins against subunit IV (which faces the matrix side in intact mitochondria) but failed to bind immune gamma-globulins against subunits II + III (which face the outer side of the inner membrane in intact mitochondria). In contrast, solubilized cytochrome c oxidase bound either of the two immune gamma-globulins. All cytochrome c oxidase molecules in the crystalline membranes are thus asymmetrically arranged so that subunit IV faces outward and subunits II + III face toward the interior. This orientation is opposite to that found with intact mitochondria. The data also suggest that the crystalline membranes form closed vesicles which are impermeable to externally added gamma-globulins.

Animals↗
PubMed1975

Glutamine synthetase forms three- and seven-stranded helical cables.

When cobaltous ion is bound to glutamine synthetase [L-glutamate:ammonia ligase (ADP-forming), EC 6.3.1.2], the two-layered hexagonal molecules polymerize face-to-face, to form long strands. The strands then wind round each other to form three- and seven-stranded cables. The structures of these cables are not immediately evident from electron micrographs because of the confusing superposition of front and back portions of the cables. But optical diffraction and filtering by the procedure of Klug and DeRosier leads to interpretable images of the cables. Because a micrograph of the seven-stranded cable contains 24 views of the glutamine synthetase molecule, it is possible to reconstruct the three-dimensional electron density of a cable and its constituent molecules at a resolution of 30--50 A. This reconstruction confirms that the symmetry of a glutamine synthetase molecule is D6. It suggests that the single subunit is an oblate ellipsoid with its minor axis (about 48 A) roughly parallel to the 6-fold axis of the molecule and its major axis (about 63 A) perpendicular to the 6-fold axis of the molecule. The subunits of the two hexagonal layers of a molecule are eclipsed. Neighboring molecules along a strand also have their hexagonal faces together, but they are rotated about the strand axis by about 7 degrees with respect to one another, rather than being eclipsed. Six outer strands are coiled about a straight central strand, and each forms identical contacts with the central strand. Moreover, these contacts between central and outer strands are apparently similar to the contacts between neighboring outer strands.

Cobalt↗
PubMedDate not supplied

Cytochrome oxidase: structural insights from electron microscopy and from secondary structure prediction.

Electron microscopic images of selectively contrasted cytochrome oxidase dimer crystals are interpreted in a manner consistent with the structure of monomers determined by Fuller et al. (J. Molec. Biol. 134, 305-327). The arms of the y-shaped monomers lie within and perpendicular to the lipid bilayer protruding approximately 25 A on the matrix side of the membrane. The cytoplasmic-side tails of two monomers spread apart in a dimer forming a large cleft. Decoration of the exposed matrix side of vesicle crystals with antisubunit IV antibody fragments indicates that subunit IV lies along the a-crystal axis roughly 20 A from the center of the dimer. A membrane propensity algorithm applied to the sequences of cytochrome oxidase subunits predicts a total of 19 transmembrane alpha-helices per monomer.

Binding Sites, Antibody↗