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

When aqueous solutions of the LDF of egg yolk and its fractions LDF₁ and LDF₂ were extracted with ethyl ether, all yielded five derived components having sedimentation rates of about 4 S, 7 S, 13 S, 15 S and 17 S. The first three of these were isolated and had molecular weights of 2.9·10⁵, 11·10⁵ and 13·10⁵, and lipid contents of 50, 67 and 44%, respectively. These components were formed sequentially in the order 7 S → 4 S → 13 S and hence all contain the same proteins, although different combinations of polypeptide chains may be present. Apparently a reduction in lipid content below 50% causes an aggregation of 4-S particles to form 13 S and other rapidly sedimenting products. The sizes of the protein moieties, computed from the molecular weight and lipid content of the native fractions LDF₁ and LDF₂ and the derived products 7 S and 4 S, are in the order 8, 4, 2 and 1, respectively, with the smallest unit size estimated to be (1.7 ± 0.16) ·10⁵. Evidently the size of the protein moiety decreases stepwise as the lipid content decreases down to 4 S and this behavior, plus aggregation at low lipid contents, yields detectable and separable components in both the natural and derived from of these lipoproteins.

Prostaglandin F_3α was isolatd from bovine lung by reversed-phase partition chromatography, silicic acid chromatography and thin-layer chromatography. Final identification was achieved by gas-liquid chromatography of a trimethylsilyl ether derivative, infrared spectroscopy and mass spectropgraphic analysis. The stereo-chemistry at C-9 was determined by an isotope technique.

Prostaglandin F_2α, earlier isolated from lung tissue of other species, was also identified.

Rats fed a vitamin E-deficient diet for 1–5 months were given intraperitoneal injections of 1 mg [¹⁴C]-α-tocopherol. After 48 h thye were killed and their lives removed and analyzed by thin-layer and column chromatography for α-tocopherol and metabolic products. Of the recovered radioactivity, about 80% was in the form of uncahnged α-tocopherol and 11% was present as a more polar compound, probably α-tocopherylquinone. No definitive evidence was obtained for the presence of a dimer. Control experiments showed that chromatography of α-tocopherol on thin-layer plates, with aqueous acetonitrile, gave rise to considerable amounts of polar material.

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  1. Chemical studies on the “phosphatido-peptide fraction” from kidney have shown that this material more properly should be called a phosphoinositide complex.

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  2. Glycerophosphate, inositol mono-, di- and triphosphate were separated from alkaline hydrolysates by means of paper chromatography.

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  3. Six fractions were obtained by column chromatography from the deacylated phosphoinositide complex and identified as inositol monophosphate, glycerophosphate, inositol diphosphate, glycerylphosphoryl inositol, glycerylphosphoryl inositol phosphate, and glycerylphosphoryl inositol diphosphate.

• 4.

  4. These phosphates, presumably as the inositides, are believed to be responsible for the hgh metabolic activity of this fraction as measured by radiophosphorus.

• 1.

  1. Puromycin (10⁻⁴ M), puromycin aminonucleoside (10⁻⁴ M) and dexamethasone (4·10⁻⁸ M) decreased the uptake and conversion of glucose to CO₂, glyceride-glycerol and fatty acid by incubated rat-adipose tissue. These substances had little effect on the metabolism of fructose or pyruvate by adipose tissue. Puromycin blocked or decreased the incorporation of glucose, fructose, and pyruvate carbon into protein; aminonucleoside and dexamethasone had little effect.

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  2. Puromycin blocked the stimulation of protein synthesis by insulin but did not alter the other actions of insulin or the effects of dexamethasone and epinephrine on adipose tissue.

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  3. Insulin decreased the conversion of pyruvate to lactate and increased its conversion to fatty acid in the presence and the absence of puromycin.