Papers by Donald Engelman
Supplementary figures and figure legends from Ku80-Targeted pH-Sensitive Peptide–PNA Conjugates Are Tumor Selective and Sensitize Cancer Cells to Ionizing Radiation
Fig. S1: pHLIP-αKu80(γ) binds to the mouse Ku80 sequence. Fig. S2: Validation of tumor vs. stroma... more Fig. S1: pHLIP-αKu80(γ) binds to the mouse Ku80 sequence. Fig. S2: Validation of tumor vs. stromal cell sorting in EMT6-GFP cells. Fig. S3: Partial suppression of Ku80 expression induces radiosensitivity in cultured cancer cells. Fig. S4: pHLIP-αKu80(γ) causes tumor radiosensitization. Fig. S5: pHLIP-αKu80(γ) causes in vitro radiosensitization. Fig. S6: pHLIP-αKu80(γ) does not induce electrolyte abnormalities. Fig. S7: pHLIP-αKu80(γ) does not cause bone marrow suppression.
Bilayer Structure in Membranes
Nature, Mar 1, 1971
Diffraction analysis of dispersions of membranes makes it possible to study membranes not in regu... more Diffraction analysis of dispersions of membranes makes it possible to study membranes not in regular arrays. Such analysis shows that a phospholipid bilayer is a predominant structural component of membranes with various different functions.
Electrostatics Appendix
Garland Science eBooks, Nov 19, 2021
Information Transfer
Garland Science eBooks, Nov 19, 2021
Bioenergetics
Garland Science eBooks, Nov 19, 2021
Neutron Diffraction Studies of Bacteriorhodopsin Structure
Springer eBooks, 1984
Halobacterium halobium is a microorganism that can survive only in solutions containing more than... more Halobacterium halobium is a microorganism that can survive only in solutions containing more than 12% salt (1). When oxygen supplies become limited, the organism synthesizes a specialized region in the plasma membrane that converts visible light energy into an electrochemical gradient by pumping protons across the plasma membrane out of the cell (2). This specialized membrane can be isolated in a stable form at low ionic strength (3,4) and is known as the purple membrane by virtue of its strong pigmentation. Purple membrane is 75% protein and only 25% lipid. The single protein species whose retinal prosthetic group is responsible for the purple color is called bacteriorhodopsin, by analogy with the vertebrate visual pigments. As shown by x-ray diffraction studies, bacteriorhodopsin exists in a hexagonal lattice in the plane of the membrane bilayer, and the packing arrangement is described by the two-dimensional crystallographic space group p3 (5).
Biophysical Journal, Oct 1, 1984
Cytochrome b5 was asymmetrically reconstituted into small lipid vesicles made of a highly deutera... more Cytochrome b5 was asymmetrically reconstituted into small lipid vesicles made of a highly deuterated phospholipid. Small-angle neutron diffraction patterns were collected in a series of H20-D20 mixtures from vesicles consisting of lipid and native or trypsinized cytochrome b5. The second moment of the radial distribution of scattering density in the vesicles was derived from these data and was compared to values calculated from three proposed models, which differ by the degree that cytochrome b5 penetrates the lipid bilayer. The model in which the hydrophobic domain of the protein is distributed across the bilayer agreed most closely with the data.
Primer on Biomolecular Structure Determination
Garland Science eBooks, Nov 19, 2021
Dimeric Transmembrane Domain of Human Glycophorin A, NMR, 20 Structures
Model of the Dimeric Transmembrane Domain of Glycophorin a
Inelastic Neutron Scattering Studies of Hexokinase in Solution
Springer eBooks, 1984
Seven years ago, at the first Brookhaven Symposium on biological neutron scattering, it was argue... more Seven years ago, at the first Brookhaven Symposium on biological neutron scattering, it was argued that inelastic neutron scattering might be productively applied to the study of biological molecular dynamics (1). While the development of this field has been slow, it now appears that such experiments may be informative. In recent studies conducted at the Institute Laue-Langevin, we have used inelastic scattering to measure changes in the thermally excited modes of hexokinase in solution when the ligand glucose is bound. The results suggest that such measurements may be useful in studies of the dynamic properties of biological macromolecules.
Journal of Molecular Biology, May 1, 1977
The Journal of Membrane Biology, Oct 1, 1985
Proteinase K digestions of bacteriorhodopsin were carded out with the aim of characterizing the m... more Proteinase K digestions of bacteriorhodopsin were carded out with the aim of characterizing the membrane-embedded regions of the protein. Products of digestions for two, eight or 24 hours were separated by high-pressure liquid chromotography. A computerized search procedure was used to compare the amino acid analyses of peptide-containing peaks with segments of the bacteriorhodopsin sequence. Molecular weight distributions of the products were determined by sodium dodecylsulfate-urea polyacrylamide gel electrophoresis. The structural integrity of the protein after digestion was monitored through the visible absorption spectrum, by X-ray diffraction of partially dried membranes, and by following release of biosynthetically-incorporated 3H leucine from the digested membranes. During mild proteolysis, bacteriorhodopsin was cleaved near the amino and carboxyl termini and at two internal regions previously identified as being accessible to the aqueous medium. Longer digestion resulted in cleavage at new sites. Under conditions where no fragments of bacteriorhodopsin larger than 9000 tool wt were observed, a significant proportion of the digested membranes retained diffraction patterns similar to those of native purple membranes. The harshest digestion conditions led to complete loss of the X-ray diffraction patterns and optical absorption and to release of half the hydrophobic segments of the protein from the membrane in the form of small soluble peptides. Upon cleavage of aqueous loop regions of the protein, isolated transmembrane segments may experience motion in a direction perpendicular to the plane of the membrane, allowing them access to protease. bacteriorhodopsin 9 membrane proteins 9 proteolysis 9 purple membranes 9 proteinase K . transmembrane peptides
Characterization of the plasma membrane of Mycoplasma laidlawii. IV. Structure and composition of membrane and aggregated components
Biochimica Et Biophysica Acta - Biomembranes, Apr 1, 1968
ABSTRACT Mycoplasma laidlawii membranes and various preparations of sodium dodecyl sulfate-dissol... more ABSTRACT Mycoplasma laidlawii membranes and various preparations of sodium dodecyl sulfate-dissolved and subsequently aggregated structures are compared with respect to amino acid composition, hexosamine composition, appearance in electron microscopy, protein to lipid ratio, buoyant density and magnesium to protein ratio. The various aggregates are virtually indistinguishable by these criteria with the exception of the microscopic appearance of the small lipoprotein aggregates and the Mg2+-induced structures derived from these aggregates.
Foundations of Membrane Structure
Garland Science eBooks, Nov 19, 2021
Membrane Protein Models: Possibilities and Probabilities
Many integral membrane proteins show hydrophobic amino acid stretches that are interpreted as tra... more Many integral membrane proteins show hydrophobic amino acid stretches that are interpreted as transbilayer helices, and experimental data often support such a contention. To what extent can hydrophobic analysis be trusted? Should one expect other folding motifs to have equal status?
Biophysical Journal, Sep 1, 1983
Cytochrome b5 was reconstituted with a highly deuterated phospholipid to form ordered multilayers... more Cytochrome b5 was reconstituted with a highly deuterated phospholipid to form ordered multilayers consisting of repeated centrosymmetric pairs of asymmetric lipid-protein bilayers. Lamellar neutron diffraction data were collected to -29 A resolution, and have been interpreted using models for the interaction of the membrane-binding domain of cytochrome bs with the lipid bilayer. A range of different models was examined, and those in which the protein penetrates well into the bilayer, possibly spanning it, are favored.
Biophysical Journal, 1986
The eventual aim of these experiments is localization of the complexed oligodeoxynucleotide by im... more The eventual aim of these experiments is localization of the complexed oligodeoxynucleotide by immunoelectron microscopy. Preliminary experiments using the octanu- cleotide, modified by addition of a 3'-terminal 1,N6- ethenoadenosine residue, resulted in a tentative placement on the subunit platform, close to the previously placed 3'-end and nearby dimethyladenosine residues (1, 2). But both the efficiency of modification and of binding of oligonucleotide in these experiments was low and the number of complexes observed was very small. We cannot thus yet be certain that these observations are both significant and specific.
The EMBO Journal, Dec 1, 1987
Current folding models for the nicotinic acetylcholine receptor (AChR) predict either four or fiv... more Current folding models for the nicotinic acetylcholine receptor (AChR) predict either four or five transmembrane segments per subunit. The N-terminus of each subunit is almost certainly extraceliular. We have tested folding models by determining biochemically the cellular location of an inter- molecular disulfide bridge thought to lie at the 6 subunit Cterminus. Dimers of AChR linked through the 6-6 bridge were prepared from Torpedo mannorata and T.californica electric organ. The disulfide's accessibility to hydrophilic reductants was tested in a reconstituted vesicle system. In right-side-out vesicles (>95% ACh binding sites outwards), the bridge was equally accessible whether or not vesicles had been disrupted by freeze-thawing or by detergents. Control experiments based on the rate of reduction of entrapped diphtheria toxin and measurements of radioactive reductant efflux demonstrated that the vesicles provide an adequate permeability barrier. In reconstituted vesicles containing AChR dimers in scrambled orientations, right-side-out dimers were reduced to monomers three times more rapidly than inside-out dimers, consistent with the measured rate of reductant permeation. These observations indicate that in reconstituted vesicles the 65-6 disulfide bridge lies in the same aqueous space as the ACh binding sites. They are most easily reconciled with folding models that propose an even number of transmembrane crossing per subunit.
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Papers by Donald Engelman