Topic
Lanosterol
About: Lanosterol is a research topic. Over the lifetime, 1239 publications have been published within this topic receiving 36737 citations. The topic is also known as: (3β)-lanosta-8,24-dien-3-ol & (3β,20R)-lanosta-8,24-dien-3-ol.
Papers published on a yearly basis
Papers
More filters
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.
17 citations
TL;DR: The T. cruzi lanosterol 14α-demethylase (Tc14DM) gene was cloned by degenerate PCR and found to be expressed in both insect and mammalian life-cycle stages of the parasite.
17 citations
TL;DR: The results using the germ cell-specific knockout model provide first in vivo evidence that the de novo synthesis of MAS and cholesterol in male germ cells is most likely not essential for spermatogenesis and reproduction and that MASs, originating from germ cells, do not cell-autonomously regulate sperMatogenesis and fertility.
17 citations
TL;DR: resolution of the enzymes has demonstrated unequivocally that cholesterol synthesis via this pathway could not have appeared biologically until membranes contained both the cytochrome P-450- and cy tochrome b5-electron transport enzymes.
Abstract: Our principal goal is the complete resolution and reconstitution of the microsomal enzymes of cholesterol biosynthesis. Elucidation of the enzymology has been achieved primarily through dissection of the membrane-bound, 19-step multienzymic process. This report describes the dissection approach through both interruption of specific steps and reconstitution of enzymes that catalyze oxidation of the 14α-methyl group. In earlier work, 4-demethylation was resolved into 3 component reactions catalyzed by: 4-methyl sterol oxidase (NAD[P] H- and O2-dependnet); steroid 4α-carboxylic acid decarboxylase (NAD-dependent); and 3-ketosteroid reductase (NADPH-dependent). The 3-ketosteroid reductase and decarboxylase have been solubilized with Lubrol WX and deoxycholate, respectively, and characterized. The 4-methyl sterol oxidase (cytochrome b5-dependent) recently has been solubilized with Renex 690. This study represents successful elucidation of a microsomal enzyme sequence by interruption of the central 10-step segment of the multienzymic formation of cholesterol from lanosterol. The initial C-32 oxidative reaction of 14α-methyl group elimination is catalyzed by a from of cytochrome P-450 that is induced by isosafrole. The induced cytochrome P-450 has been solubilized with Emulgen 913 and purified to homogeneity (17 nmol of cytochrome/mg protein). 24,25-Dihydrolanosterol is oxidized by combination of cytochrome P-450 reductase, hematin, NADPH, glutathione, and the purified, isosafrole-induced cytochrome in an artificial liposome. Oxidation product identification is underway. This study represents successful elucidation of a microsomal multienzymic sequence by solubilization and reconstitution of a segment of the pathway. The remaining enzymes under study are the Δ8→Δ7 isomerase and 3 NADPH-dependent double bond reductases that catalyze reduction of: Δ7, Δ14- Δ24-sterol double bonds. Purification of these nonoxygenrequiring enzymes is in progress. Resolution of the enzymes has demonstrated unequivocally that cholesterol synthesis via this pathway could not have appeared biologically until membranes containedboth the cytochrome P-450- and cytochrome b5-electron transport enzymes. Chemically, all enzymic attacks in the formation of cholesterol from lanosterol appear to be initiated on the α-face of the relatively planar steroids. Thus, considerable genetic pressure must have been needed for the stereospecific clearing of the steroidal α-face to form the mature membrane component, cholesterol.
17 citations
TL;DR: It is demonstrated that 15-oxime XIX is indeed a dual-action inhibitor of cholesterol biosynthesis which causes both the inhibition of P450DM and a reduction in HMGR activity.
17 citations