Showing papers on "Lanosterol published in 1981"
TL;DR: The results strongly support the suggestion that membrane-bound cytochrome b5 of rat liver microsomes is an obligatory electron carrier from NADH to 4-methyl sterol oxidase.
79 citations
TL;DR: The results are consistent with the membrane cholesterol serving in a dual role, one as a bulk component and another more specific function involving the regulation of unsaturated fatty acid uptake and thereby phospholipid biosynthesis.
59 citations
TL;DR: Normal human lymphocytes stimulated by culture in a lipid-depleted medium were used to study the post-HMG CoA regulations of cholesterol biosynthesis and an intermediate which accumulates in the cell has inhibitory properties towards H MG CoA reductase and thus could be considered as an endogenous cellular bioregulator ofolesterol biosynthesis.
44 citations
TL;DR: It is concluded that cytochrome P-450 actually exists in aerobically grown yeast and participates in the lanosterol 14 alpha-demethylation which is essential for the ergosterol (5 alpha-ergosta-5,7,22-trien-3 beta-ol) biogenesis by yeast.
39 citations
TL;DR: The oyster was concluded to synthesize cholesterol, desmosterol, isofucosterol, and 24-methylenecholesterol from acetate via squalene, probably using the lanosterol pathway.
Abstract: Sterol biosynthesis in the oyster,Crassostrea virginica, was examined by injection of [2-14C]acetate and [2,3-3H] lanosterol. The oyster incorporated [2-14C] acetate into squalene 4,4′-dimethylsterols, 4-monomethylsterols, cholesterol, desmosterol, isofucosterol, and 24-methylenecholesterol, and also converted [2-3H] lanosterol to cholesterol. Therefore, the oyster was concluded to synthesize cholesterol, desmosterol, isofucosterol, and 24-methylenecholesterol from acetate via squalene, probably using the lanosterol pathway.
31 citations
TL;DR: It is concluded that cytochrome b5 and a cyanide-sensitive enzyme are involved in the 4-dem methylation of 4,4-dimethylzymosterol, but not the 14 alpha-demethylation of lanosterol, by yeast microsomes.
31 citations
TL;DR: A simplified method is described for the preparation of 14 alpha-hydroxymethyl-4,4-dimethyl-5 alpha-cholest-8-en-e beta-ol from commercial lanosterol by a modification of the approach introduced by Fried and co-workers.
30 citations
TL;DR: Vegetative mycelia of Lagenidium giganteum and L. callinectes will metabolize cycloartenol to fucosterol and cholesterol, indicative of a sterol synthetic pathway such as is present in photosynthetic organisms.
20 citations
TL;DR: Z protein may modulate several microsomal enzymic activities of sterol biosynthesis in concert by exhibiting affinities for the membrane as well as low-molecular-weight cofactors, substrates, and metabolic effectors.
17 citations
TL;DR: The influences of clotrimazole and triadimefon have to be considered as an inhibition of desmethylation reactions involved in ergosterol synthesis of yeasts and fungi with a concomitant decreased production of mevalonate.
Abstract: Clotrimazole and triadimefon are known as potent inhibitors of ergosterol synthesis in pathogenic yeast and fungi, respectively. As their mode of action generally the inhibition of sterol desmethylation reactions is accepted. We report about a second effect, a "feed-back" inhibition of 3-hydroxy-3-methyl-glutaryl (HMG)-CoA-reductase by accumulation of ergosterol precursors. Addition of lanosterol to intact cells leads to an inhibition of HMG-CoA-reductase as well, but not to fungistatic effects. From the reported data the influences of clotrimazole and triadimefon have to be considered as an inhibition of desmethylation reactions involved in ergosterol synthesis of yeast and fungi with a concomitant decreased production of mevalonate.
13 citations
TL;DR: Criteria of the multienzyme system catalyzing lanosterol metabolism and the role of SCP in this process are defined and its remarkable abundance, ubiquitous occurrence, and recently discovered functions in fatty acid metabolism suggest SCP plays an important regulatory role in lipid metabolism.
TL;DR: In this paper, the authors synthesized twelve lanosterol analogs with different sizes of side chain and 20-iso-24-dihydrolanosterol (37) for biological studies.
Abstract: Starting from lanosteryl acetate (1b), we synthesized twelve lanosterol analogs (cf. Chart 1-3 ; 9, 11, 14, 16, 18a, 19, 26, 27a, 28, 29, 30, 32) with different sizes of side chain and 20-iso-24-dihydrolanosterol (37), for biological studies. The analogs have shorter side chains than 1b except for the 24-ethylidene derivative (19) and 37. 20-Iso-24-di-hydrolanosterol (37) was prepared via 20-iso-22-dehydro-24-dihydrolanosterol [obtained by the Wittig reaction of 20R, S-aldehyde mixture (6, 33) with isoamyl triphenylphosphonium iodide, followed by column chromatographic separation].
TL;DR: It is found that both sterols have a second, but distinct, site of action, distal to the formation of mevalonic acid, which is compatible with a specific inhibition of the metabolism of lanosterol and 24,25-dihydrolanosterol by the delta 7-3 beta, 15 alpha, 32-triol and a specific inhibiting of the delta 8 leads to delta 7 isomerase by the Delta 6-3 Beta, 15alpha,32-
TL;DR: The data obtained are consistent with a biosynthetic pathway in which the pro-E isopropylidene methyl group of the Δ24-precursor becomes thepro-R isoprostyl methyl group in isofucosterol.
Abstract: [26-3H]Lanosterol (16) was administered to Pinus pinea and the [26-3H]isofucosteryl acetate (6) obtained was chemically transformed into [26-3H]cholesterol (13). Compound (13) was incubated with rat-liver mitochondria to yield [3-3H] propionic acid. The data obtained are consistent with a biosynthetic pathway in which the pro-E isopropylidene methyl group of the Δ24-precursor becomes the pro-R isopropyl methyl group in isofucosterol.
TL;DR: The fatty acyl moiety in lanosterol and dihydrolanosterol esters was determined by measurement of the metastable transition [M--15]+ leads to [M-15-fatty acid]+ which occurs in the first field free region of a double focusing mass spectrometer.
Abstract: The fatty acyl moiety in lanosterol and dihydrolanosterol esters was determined by measurement of the metastable transition [M--15]+ leads to [M--15-fatty acid]+ which occurs in the first field free region of a double focusing mass spectrometer. The analysis was made by accelerating voltage scanning. Quantification of the esters was made by single reaction monitoring, using calibration curves measured in the presence of the corresponding matrix. The detection limit for a selected lanosterol ester was below 300 pg. using this technique, each individual lanosterol and dihydrolanosterol ester was detected and quantified in a sample of wool wax. Interference from dihydroagnosterol esters is very likely, but interference from sterol esters which do not have a 4-methyl group is unlikely since the corresponding metastable peak is of very low intensity.
TL;DR: In this article, the synthesis of 4,4,14α-trimethyl-19 (10 → 9β) abeo-steroids (iv, (v), and (Vl) with two-and five-carbon side chains from lanosterol is described.
Journal Article•
Journal Article•
01 Jan 1981
TL;DR: This chapter discusses the biosynthesis of sterols, where green plants and most algae synthesize sterols from mevalonic acid via 2,3-oxidosqualene, but the product of cyclization is cycloartenol, not lanosterol.
Abstract: This chapter discusses the biosynthesis of sterols. It has been seen that certain stereochemical aspects of reaction mechanisms are relevant to the biosynthesis of sterols. Green plants and most algae synthesize sterols from mevalonic acid via 2,3-oxidosqualene, but the product of cyclization is cycloartenol, not lanosterol. Though carotenoids are not sterols, their formation in plants is important because the early intermediates in sterol biosynthesis also lie on the pathway to carotenoids. Insects cannot synthesize sterols, the metabolic block occurring between farnesyl pyrophosphate and squalene. Nevertheless, they have an absolute requirement for cholesterol as structural constituent of their cells and as precursor for the formation of hormones and other steroid metabolites. Most insects cannot grow or undergo metamorphosis unless cholesterol, or a sterol precursor of cholesterol, is present in the diet. The only exceptions are insects that obtain their sterol from symbiotic microorganisms. Although insects are unable to synthesize sterols, many of them can synthesize isoprenoids from acetate or mevalonic acid.
TL;DR: In this article, the authors synthesized twelve lanosterol analogs with different sizes of side chain and 20-iso-24-dihydrolanosterol (37) for biological studies.
Abstract: Starting from lanosteryl acetate (1b), we synthesized twelve lanosterol analogs (cf. Chart 1-3 ; 9, 11, 14, 16, 18a, 19, 26, 27a, 28, 29, 30, 32) with different sizes of side chain and 20-iso-24-dihydrolanosterol (37), for biological studies. The analogs have shorter side chains than 1b except for the 24-ethylidene derivative (19) and 37. 20-Iso-24-di-hydrolanosterol (37) was prepared via 20-iso-22-dehydro-24-dihydrolanosterol [obtained by the Wittig reaction of 20R, S-aldehyde mixture (6, 33) with isoamyl triphenylphosphonium iodide, followed by column chromatographic separation].