Showing papers on "Lanosterol published in 1974"
TL;DR: Porphyrin intermediates alleviate the lipid requirement of ole2 and ole3 and restore respiratory competence and it is concluded that the primary defects in these mutants are lesions in porphyr in biosynthesis.
70 citations
TL;DR: A cell-free system has been obtained from Saccharomyces cerevisiae which is capable of efficiently converting lanosterol 1 to a mixture of 4-demethyl sterols, quantitatively the most important identifiable component of which was zymosterol as discussed by the authors.
48 citations
TL;DR: In this article, mutants of Saccharomyces cerevisiae were isolated which required ergosterol or cholesterol as the only lipid supplement and showed complete absence of respiratory cytochromes.
47 citations
TL;DR: The results demonstrate that the renal cortex is the primary site of mevalonic acid metabolism within the kidney and that the glomerulus is responsible for 95% of the mevalonate metabolized by the renal cerebral cortex.
37 citations
TL;DR: A mutant strain of Saccharomyces cerevisiae which requires only a sterol for growth has been isolated and Sterol analysis suggests a block in ergosterol formation at the level of conversion of squalene to lanosterol.
35 citations
TL;DR: Results indicated a block in removal of the methyl group at C-14 of lanosterol in nystatin resistant and ergosterol requiring mutants and of the wild type parent of Saccharomyces cerevisiae were separated by a newly developed procedure and were identified.
32 citations
TL;DR: The metabolism of Delta(7)-cholestenol, cholesterol, and cholestanol was examined in a patient with cerebrotendinous xanthomatosis after intravenous pulse-labeling with a mixture of dl-[2-(14)C]mevalonate and stereospecific 3S,4S,3R,4R-[4-(3)H]meValonate], showing that sterol synthesis proceeded in the following sequence.
29 citations
TL;DR: Cholesterol and a number of other 4-demethyl sterols stimulated vegetative growth of Phytophthora infestans in liquid culture and on agar media and all sterols tested, including lanosterol, promoted the formation of sporangia by the fungus.
Abstract: Cholesterol and a number of other 4-demethyl sterols stimulated vegetative growth of Phytophthora infestans in liquid culture and on agar media. The 4,4′-dimethyl sterol lanosterol was inactive in this respect. A free 3-β-hydroxyl group appeared to be necessary for activity. All sterols tested, including lanosterol, promoted the formation of sporangia by the fungus. Lanosterol, inactive in stimulating vegetative growth, had very little effect on the stimulation of growth and sporulation by the active sterol, stigmasterol. The major 4-demethyl sterols in potato leaves were tentatively identified as cholesterol, stigmasterol and β-sitosterol. The other major sterol was the 4,4′dimethyl sterol, cycloartenol. Potato varieties differed in the relative amounts of these major sterol constituents present in the leaves. No relationship between the sterol content of potato leaves and resistance to infection by P. infestons was evident. Sterol preparations from a resistant and susceptible potato variety stimulated growth of P. infestons by a similar amount despite large differences between the preparations in the proportions of their constituents.
28 citations
TL;DR: An analysis of the total sterol content has been made of a yeast strain during aerobic adaptation, and Δ7-Zymostenol has been tentatively identified as a product previously unreported in yeast.
Abstract: An analysis of the total sterol content has been made of a yeast strain during aerobic adaptation. Transmethylation occurs principally at the 4-demethylsterol level, but conditions were obtained wherein a small fraction of the transmethylations were with 4α-methyl precursors. Δ7-Zymostenol has been tentatively identified as a product previously unreported in yeast. Esterification was observed in all sterol intermediates and products. Cell-free cyclization of 2,3-epoxy-22-methylene squalene to 24-methylene lanosterol occurs with yeast.
25 citations
TL;DR: Under these conditions, 4,4-dimethylcholesta-8,14-dienol is the most efficient precursor of cholesterol and cholest-7-enol, and dihydro[(14)C]lanosterol is better than 4, 4-dim methylcholEST-8(14)-enol.
Abstract: Cholest-8(14)-enol is the major radioactive component of the 4-di-demethyl sterol fraction biosynthesized from 4,4-dimethyl[2-3H2]cholest-8(14)-enol by rat liver microsomal fractions, and therefore the first steps in the biosynthesis of cholesterol from the latter compound probably involve removal of the 4-methyl groups. 4,4-Dimethylcholesta-8,14-dienol therefore is not an intermediate in this process, although its presence in the incubation medium at a concentration of 0.146mm almost completely inhibits the demethylation of 4,4-dimethyl[2-3H2]cholest-8(14)-enol. Nor is cholesta-8,14-dienol an intermediate in the conversion of cholest-8(14)-enol into cholest-7-enol and cholesterol. With 4,4-dimethyl[2-3H2]cholesta-8,14-dienol as the cholesterol precursor, 4,4-dimethylcholest-8(9)-enol becomes heavily labelled and there is very little radioactivity associated with cholesta-8,14-dienol.In this case, the most heavily labelled 4-di-demethyl sterols are cholest-7-enol and cholesterol with the former predominating. There is little or no radio-activity associated with cholest-8(14)-enol. A similar labelling pattern amongst the 4-di-demethyl sterols was observed with dihydro[14C]lanosterol as the precursor. The first step therefore in the synthesis of cholesterol from the 4,4-dimethyl[2-3H2]dienol is reduction of the Δ14(15) bond and not removal of the 4α-methyl group. Depending on the nature of the precursor, addition of the soluble fraction of the cell to the microsomal fraction resulted in a two- to four-fold stimulation of 4-di-demethyl sterol biosynthesis from the 4,4-dimethyl sterols studied. Under these conditions, 4,4-dimethylcholesta-8,14-dienol is the most efficient precursor of cholesterol and cholest-7-enol, and dihydrolanosterol is better than 4,4-dimethylcholest-8(14)-enol.
22 citations
TL;DR: It is suggested that the cholesterol concentration in the culture medium influences the rate of sterol formation by the kidney cell, and cholesterol appears to be essential to cultured human kidney and de novo synthesis by the cells in culture is not adequate to meet their requirements for growth.
TL;DR: The findings indicate that the heat-stable protein factor present in the supernatant fractions from extrahepatic tissues is perhaps identical to that in liver, but that theHeat-labile factor in extrahePatic tissues, which catalyzes the cyclization of squalene to lanosterol, differs in some respect from that in Liver.
TL;DR: Inotodiol 1a has been stereospecifically synthesised from lanosterol in six steps and Horeau's method utilised to demonstrate the R-configuration at C-22.
TL;DR: (S)-Squalene 2,3-epoxide was found to be the exclusive precursor of lanosterol in pig liver, Lanosterol, and ergosterols in yeast, and β-amyrin, lupeol and cycloartenol in pea seedlings.
Abstract: (S)-Squalene 2,3-epoxide was found to be the exclusive precursor of lanosterol in pig liver, lanosterol, and ergosterol in yeast (Saccharamyces cerevisiae), and β-amyrin, lupeol and cycloartenol in pea seedlings.
TL;DR: The 4-demethyl sterols of Echinus esculentus consisted of cholesterol as the major component, with lower concentrations of nine other C(26, C(27), C(28) and C(29) Delta(5) sterols.
Abstract: 1. The 4-demethyl sterols of Echinus esculentus consisted of cholesterol as the major component, with lower concentrations of nine other C(26), C(27), C(28) and C(29) Delta(5) sterols. 2. [2-(14)C]Mevalonic acid was readily incorporated by the urchin into squalene, lanosterol and desmosterol but only to a small extent into cholesterol. 3. [26-(14)C]Desmosterol did not appear to be reduced to give cholesterol, but conversion of 5alpha-[2-(3)H(2)]lanost-8-en-3beta-ol into cholesterol was observed. 4. No C-24 dealkylation of [4-(14)C]sitosterol or metabolism of [4-(14)C]cholesterol could be detected.
TL;DR: It is shown that native placental S 105 has an important squalene binding capacity but is not very efficient in activating liver or placental epoxidase, and should be related to different factors.
TL;DR: The stereochemistry of addition of the 25-proton in the Δ24 reduction of lanosterol to cholesterol in vivo in the rat is shown to be the same as that in the S-10 fraction of rat liver homogenates.
Abstract: The stereochemistry of addition of the 25-proton in the Δ24 reduction of lanosterol to cholesterol in vivo in the rat is shown to be the same as that in the S-10 fraction of rat liver homogenates.It is also shown that oxidation of [1,2-3H2]octan-1-ol by the Pfitzner–Moffatt method proceeds with complete removal of tritium from C-2 of octanol. A similar oxidation of [25-3H]-5α-cholestane-3β,26-diol to 3-oxo[25-3H]-5α-cholestan-26-al resulted in the loss of 23% of tritium. In contrast, Collins oxidation of [1,2-3H2]octan-1-ol to octanal did not involve any loss of tritium from C-2.
TL;DR: In this paper, a new method for the degradation of the side chain of lanosterol and bile acids is described, brought about by the action of molecular oxygen on basic solutions of the phenyl ketones ( 1, 7, and 15 ).
TL;DR: In this article, the incubation of terminally modified squalene 2,3-oxide analogs with the enzyme preparation of hog liver yielded the corresponding lanosterol analogs, respectively, at different conversion rates.
Abstract: The incubation of terminally modified squalene 2,3-oxide analogs with the enzyme preparation of hog liver yielded the corresponding lanosterol analogs, respectively, at different conversion rates. The interaction of 2,3-oxidosqualene cyclase with the substrates has thus been found to be influenced by the bulk of the terminal moiety.