Biochimica et Biophysica Acta (BBA) - Specialized Section on Lipids and Related Subjects最新文献

• 1.

  1. The lipids of liver were reexamined for polyphosphoinositide, previously reported absent. The presence of a diphosphoinositide (DPI) was revealed by the isolation of inositol diphosphate (IP₂) from an acid hydrolysate, and its glyceryl derivative from an alkaline hydrolysate of the concentrated phospholipid fraction.

• 2.

  2. Starting with lipids extracted from liver and pancreas by azeotropic dehydration with 1,2-dichloroethane, materials soluble in acetone and alcohol were removed. After partition of the alcohol-insoluble phospholipids in CCl₄-light petroleum-methanol-H₂O (31:31:35:3, V/V), the non-polar fraction was assayed for inositol polyphosphate by chromatographic fractionation of the acid hydrolysate on Dowex-2 X8 Cl⁻ A diphosphate mixture eluted by NaCl or LiCl was separated by refractionation with a formate system yielding IP₂ and glycerol diphosphate.

• 3.

  3. The mixed glyceryl derivatives of IP₂ and glycerol diphosphate were secured by chromatographic fractionation of the alkaline hydrolysate. Based on the recovery of IP₂ and its glyceryl derivative, the content of DPI in the original pork liver lipid is 0.28 mmoles/kg.

• 4.

  4. DPI could not be extracted by ether from acetone-dehydrated fresh beef liver but was extracted with neutral chloroform-methanol (2:1, V/V).

• 5.

  5. Most of the IP₂ found in pacreatic lipid occured in material insoluble in CHCl₃ and in the CCl₄-light petroleum solvent.

The molecular weight of β-ganglioside was measured by vapor pressure depression in a number of different solvents. The molecular weight was found to be near 1665, corresponding to a structure containing sphingosine, stearic acid, glucose, galactose, N-acetylgalactosamine, and two N-acetylneuraminic acid residues. In aqueous solution, the ganglioside associated to form a micelle structure with an aggregate weight of 200 000 or greater. The critical micelle concentration was found to be 1.0 · 10⁻⁵ M. A discussion of these properties is presented.

Both gangliosides are bound acetycholine are higher in grey matter than in white. The subcellular distributions of these two compounds appear to be parallel in rat brain, occuring primarily in the crude mitochondrial fraction, and upon further fractionation both gangliosides and bound acetycholine appear in the pinched-off nerve ending fraction. The synaptic vesicle isolated after disruption of the nerve endings by osmotic shock contains both acetylcholine and gangliosides. This parallel distribution and the physical properties of gangliosides suggest a functional role for gangliosides in the transport of acetylcholine from synaptic vesicles through the presynaptic membrane.

• 1.

  1. Brucella abortus Bang was grown aerobically on glycerol-thionin-agar. The “free lipids” extracted from these bacteria (yielding 1.% of dry wt.) inhibit the Schultz-Dale reaction in the brucellose system.

• 2.

  2. The lipid mixture was separated by acetone yieldng 81.2% acetone-insoluble fraction.

• 3.

  3. The acetone-insoluble part was separated by column chromatography under thin-layer chromatographic control. According to appearing or disappearing of a component in the thin-layer chromatogram the fractions obtained by column chromatography were combined to form 30 collective fractions. Each of them consists of several components.

• 4.

  4. By preparative thin-layer chromatography 7 aminophosphatides were isolated from the column-chromatographic fractions.

• 5.

  5. Among the 7 phosphatides phosphatidylethanolamine, phosphatidylserine, lecithin and lysolecithin were identified. One of the remaining 3 phosphatides contains ethanolamine, two contain choline among their hydrolysis products. Moreover, they contain phosphate esters other than glycerophosphate.

• 6.

  6. Among the component fatty acids of the 7 phosphatides saturated acids predominate, especially palmitic acid. Monoethenoic acids and octadecadienoic acid are also present. There are also odd-numbered straight-chain (n-C₁₅, n-C₁₇, n-C₁₉) and hydroxy fatty acids in low concentrations and perhaps saturated methyl-branched C₁₇, C₁₉ and C₂₁ acids. All phosphatides contain C₁₉-cyclopropane acid which was reported recently.

• 1.

  1. A method has been developed for the isolation and estimation of unesterified fatty acid in tissue extracts. This is based on treatment of extracted lipid with diazomethane followed by isolation of the methyl esters by chromatography on a thin layer of alumina.

• 2.

  2. It has been found that mouse brain contains appreciable quantities of unesterified fatty acid.

• 3.

  3. The principal acids were palmitic, stearic, oleic and arachidonic acids.

• 4.

  4. When mouse brain was incubated with sodium [I-¹⁴C]acetate for periods up to 6 h, 28%–66% of the incorporation into lipid was into unesterified fatty acid.

• 5.

  5. Of the principal acids acetate was incorporated into palmitic acid only.