Notes- Method for the Cleavage of Osmate Esters

Baran, John S.

doi:10.1021/jo01072a030

Cited by 99 publications

(36 citation statements)

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“…However, we note that osmium may also label trans-double bonds present in sphingomyelins. Cholesterol is another potential target of osmium, based upon oxidation of androstenolone that shares the same 5,6 double bond as cholesterol (Batan, 1960). Along with actively signaling receptors, these regions recruit a long list of signaling proteins, including tyrosine kinases (Syk and BTK), adaptors and guanine nucleotide exchange factors (Gab2, Grb2, and Vav), enzymes involved in phosphoinositide metabolism (PLC␥2, PI 3-kinase, and PTEN), and negative regulatory molecules (Cbl) (Wilson et al, 2001(Wilson et al, , 2002.…”

Section: Discussionmentioning

confidence: 99%

Markers for Detergent-resistant Lipid Rafts Occupy Distinct and Dynamic Domains in Native Membranes

Wilson

Steinberg

Liederman

et al. 2004

MBoC

187

183

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Lipid rafts isolated by detergent extraction and sucrose gradient fractionation from mast cells are enriched for the glycosylphosphatidylinositol-linked protein Thy-1, the ganglioside GM1, palmitoylated LAT, and cross-linked IgE receptors, Fc⑀RI. This study addresses the relationship of fractionation data to the organization of raft markers in native membranes. Immunogold labeling and electron microscopy shows there is little or no colocalization of the raft markers Thy-1, GM1, and LAT with each other or with Fc⑀RI on native membrane sheets prepared from unstimulated cells. External cross-linking of Thy-1 promotes coclustering of Thy-1 with LAT, but not with GM1. Thy-1 and LAT clusters occur on membrane regions without distinctive features. In contrast, external cross-linking of Fc⑀RI and GM1 causes their redistribution to electron-dense membrane patches independently of each other and of Thy-1. The distinctive patches that accumulate cross-linked Fc⑀RI and GM1 also accumulate osmium, a stain for unsaturated lipids, and are sites for coated vesicle budding. Electron microscopy reveals a more complex and dynamic topographical organization of membrane microdomains than is predicted by biochemical analysis of detergent-resistant membranes. INTRODUCTIONOrdered regions of membrane, known as microdomains, lipid rafts, detergent-resistant membranes (DRMs), and other abbreviations are thought to be critical sites of signal propagation and membrane trafficking (Edidin, 1997(Edidin, , 2001Simons and Ikonen, 1997;Anderson, 1998; London, 1998, 2000;Jacobson and Dietrich, 1999;Langlet et al., 2000;Anderson and Jacobson, 2002). Analysis of these regions typically begins with detergent solubilization of whole cells followed by sucrose density gradient centrifugation and the recovery of detergent-resistant membranes from the light fractions of the gradient. The DRMs are enriched for caveolin, glycosylphosphatidylinositol-linked (GPI-linked) proteins, glycosphingolipids, GM1 ganglioside, and cholesterol, suggesting that these components are associated in the liquid-ordered (l o ) phase of the lipid bilayer (Schroeder et al., 1994;Ahmed et al., 1997). The interpretation of gradient centrifugation experiments remains controversial. There is evidence that detergents may force associations between components that are not colocalized in intact cells (Mayor and Maxfield, 1995), and fractionation results are known to be dramatically altered by varying the concentration of Triton X-100 (Field et al., 1999;Parolini et al., 1999), by use of alternative detergents (Montixi et al., 1998;Surviladze et al., 1998) or by omission of detergent altogether (Ilangumaran et al., 1999;Harder and Kuhn, 2000;Surviladze et al., 2001). Methods to observe membrane segregation in situ have also generated controversy. Results based on light and fluorescence microscopy of proteins and lipids, including refinements of the established fluorescence recovery after photobleaching methods and new single particle tracking methods, have led some investigators to co...

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Section: Discussionmentioning

confidence: 99%

Markers for Detergent-resistant Lipid Rafts Occupy Distinct and Dynamic Domains in Native Membranes

Wilson

Steinberg

Liederman

et al. 2004

MBoC

187

183

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“…The mixture immediately set t o a mass of brown crystals. After 30 minutes, the mixture was treated with a solution of sodium bisulphite in 60 ml of water and 40 ml of pyridine (15) and the mixture stirred until a clear orange solution was obtained. The solution was thoroughly extracted with chloroform and the extract was dried over magnesium sulphate.…”

Section: 44-mentioning

confidence: 99%

“…On warming of the mixture to room temperature, the iodine had dissolved and the resulting mixture was taken up in benzene for the NMR experiment. The cis-diol was prepared by osmiuiu tetraoxide oxidation in pyridine (14) and decomposition of the osmiate with sodium bisulphite (15 with tetralneth~kilane (1%) as internal reference. The scale is in 7 units.…”

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confidence: 99%

THE CONFORMATIONS IN SOLUTION OF trans-CYCLOHEXENE DIHALIDES AND cis- AND trans-1,2-CYCLOHEXANEDIOLS AND DERIVATIVES

Lemieux¹,

Lown²

1964

Can. J. Chem.

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trans-1,4,4-Trideuteriocyclohexene dichloride, dibromide, and diiodide and the 1,4,4-trideuterio-cis-and trans-1,2-cyclohexanediols together with their 0-acetyl, 0-tosyl, and O-isopropylidene derivatives were synthesized. Their nuclear magnetic resonance (NMR) spectral parameters were obtained with a spectrometer operating a t 100 h1c.p.s. and employing double irradiation to establish the chemical shifts and the signs of the coupling constants. The interpretation of the data according to expectations based on the Karplus relationship, for dihedral angles and coupling constants, support the conformational equilibria assigned t o the tuans-dichloride and trans-dlbromide of cyclohexene on the basis of dipole moment measurements (previously published results). The results indicate that trans-cyclohexene diiodide exists t o about 84yo in the diaxial conformation. I11 the case of the 1,2-cis-disubstituted cyclohexanes, the occurrence of the signal for the 3-hydrogen in trans relation t o the 2-hydrogen a t loxver field than its geminal 3-hydrogen is assigned to the deshielding influence on the 3-hydrogen when in axial orientation by a n opposing axial oxygen a t the 1-position. Support for this contention was obtained by determination of the chemical shifts of the geminal hydrogens a t the 3-and 5-positions of the cis-and trans-4-t-butyl-2,2,6,6-tetradeuterio-1-methylcyclohexanols. The conformational equilibria indicated for the l,2-diol, l,2-diacetox), and 1,2-ditosyloxy trans derivatives of 1,4,4-trideuteriocyclohexane by N h l R parameters obtained from the spectrum of the 0-isopropylidene derivatives of the tuans-diol allowed conclusions regarding the non-bonded interaction energies involved. The Karplus relation had to be adjusted to the form, J+ = 14.7 cosZ@ -0.2 (0'-4-90") and J+ = 11.2 cos24 -0.2 (90"-4-18O0), t o accommodate the results. Solvent effects on conformation are noted. Also, the investigation provided further evidence for the opposite signs of the coupling constants for geminal and vicinal hydrogens. A consideration of the chemical shifts observed for a variety of derivatives of cyclohexanol appears to indicate that intramolecular shielding effects are better accounted for on the basis of neighboring atomic groupings than on the basis of individual chemical bonds.Attempts have been made previously to study-the conformational equilibria of the trans-cyclohexene dihalides in benzene solution by the measurement of dipole moments (1) and by observation of the chemical shifts of protons adjacent to the halogen atoms (2). Both of these methods suffer from disadvantages; in the first, it is impossible t o estimate the molecular dipole in the diaxial conformation, i.e. of allowing for dipolar contributions from the cyclohexane skeleton (3). The second method requires the assumption that the usual orientational effects on chemical shifts apply (4,5). This latter assumption, as it transpired, proved to be justified in the case of the trans-dihalides but could not have been foreseen and would not hav...

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“…The reaction of 1 with osmic acid in dioxane or pyridine, following published directions (4)(5)(6), gave a nearly quantitative yield of crude material which showed only one spot on a t.1.c. Distillation provided pure 1,6-anhydro-4-deoxy-P-DLribo-hexopyranose (3, R = H) in 96% yield.…”

Section: Resultsmentioning

confidence: 99%

Total Synthesis of Several Monodeoxy and Dideoxy-DL-hexopyranoses from 6,8-Dioxabicyclo[3.2.1]oct-2-ene and 6,8-Dioxabicyclo[3.2.1]oct-3-ene

Murray¹,

Brown²

1971

Can. J. Chem.

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Reaction of osmic acid with 6,s-dioxabicyclo[3.2.l]oct-3-ene (1) gave 1,6-anhydro-4-deoxy-P-DL-ribohexopyranose (3, R = H) which was hydrolyzed to 4-deoxjr-a,P-DL-ribo-hexopyranose (4, R = H). Conversion of 1 to 1,6:2,3-dianhydro-4-deoxy-~-~~-ribo-hexopyranose(5) followed by treatment of 5 with lithium aluminum hydride, gave 1,6-anhydro-3,4-dideoxy-~-~~-erythro-hexopyranose (6, R = H), and this in turn was hydrolyzed to 3,4-dideoxy-a,P-DL-erythro-hexopyranose (7, R = H).Reaction of osmic acid with 6,s-dioxabicyclo[3.2.l]oct-2-ene (2) gave 1,6-anhydro-2-deoxy-P-DL-ribohexopyranose (8, R = H), which was hydrolyzed to 2-deoxy-DL-ribo-hexopyranose (9, R = H). Compound 2 was converted to 1,6:3,4-dianhydro-2-deoxy-P-DL-ribo-hexopyranose (10) which was hydrolyzed by aqueous base to 1,6-anhydro-2-deoxy-P-DL-arabino-hexopyranose (12) and this in turn was hydrolyzed by dilute hydrochloric acid to 2-deoxy-a,P-DL-arabino-hexopyranose (2-deoxy-DL-glucose) (13). The reaction of 10 with lithium aluminum hydride gave 1,6-anhydro-2,3-dideoxy-P-DL-erythro-hexopyranose (14).Yields were good to excellent in each of the above reactions.La rkaction de I'acide osmique avec le dioxa-6,8 bicyclo[3.2.1] octkne-3 (1) conduit A I'anhydro-1,6d6soxy-4 P-DL-ribo-hexapyranose (3, R = H) qui par hydrolyse fournit le dksoxy-4 a,P-DL-ribo-hexapyranose (4, R = H). Le composk 1 peut Ctre transform6 successivement en dianhydro-1;6:2,3 dksoxy-4 P-DL-ribo-hexapyranose (5), puis par traitement par LiAIH, en anhydro-1,6 didksoxy-3,4 P-DL-erythrohexapyranose (6, R = H) et finalement, par hydrolyse, en didksoxy-3,4 a,P-DL-erythro-hexapyranose (7, R = H). Par ailleurs I'action de l'acide osmique sur le dioxa-6,8 bicyclo[3.2.1] octene-2 (2) fournit I'anhydro-1,6 dksoxy-2 P-DL-ribo-hexapyranose (8, R = H) qui conduit, par hydrolyse, au desoxy-2 DL-ribo-hexapyranose (9, R = H). On Reut aussi transformer le composk 2 pour obtenir successivement le dianhydro-1,6:3,4 dksoxy-2 j3-DL-ribo-hexapyranose (lo), puis par hydrolyse en milieu basique en anhydro-1,6 dhoxy-2 P-DL-arabino-hexapyranose (12);et finalement par hydrolyse en milieu acide chlorhydrique diluk en dksoxy-2 a,P-DL-arabino-hexapyranose (dksoxy-2 DL-glucose) (13). La rkaction de 10 avec LiAlH, fournit l'anhydro-1,6 didksoxy-2,3 P-DL-erythro-hexapyranose (14).Dans chacune des reactions dkrites ci-haut les rendements sont excellents.

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Notes- Method for the Cleavage of Osmate Esters

Cited by 99 publications

References 1 publication

Markers for Detergent-resistant Lipid Rafts Occupy Distinct and Dynamic Domains in Native Membranes

Markers for Detergent-resistant Lipid Rafts Occupy Distinct and Dynamic Domains in Native Membranes

THE CONFORMATIONS IN SOLUTION OF trans-CYCLOHEXENE DIHALIDES AND cis- AND trans-1,2-CYCLOHEXANEDIOLS AND DERIVATIVES

Total Synthesis of Several Monodeoxy and Dideoxy-DL-hexopyranoses from 6,8-Dioxabicyclo[3.2.1]oct-2-ene and 6,8-Dioxabicyclo[3.2.1]oct-3-ene

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