Showing papers on "Lanosterol synthase published in 2004"
TL;DR: The target protein with an inhibitor that showed cholesterol lowering in vivo opens the way for the structure-based design of new OSC inhibitors, and the complex with the reaction product lanosterol gives a clear picture of the way in which the enzyme achieves product specificity in this highly exothermic cyclization reaction.
Abstract: In higher organisms the formation of the steroid scaffold is catalysed exclusively by the membrane-bound oxidosqualene cyclase (OSC; lanosterol synthase). In a highly selective cyclization reaction OSC forms lanosterol with seven chiral centres starting from the linear substrate 2,3-oxidosqualene. Valuable data on the mechanism of the complex cyclization cascade have been collected during the past 50 years using suicide inhibitors, mutagenesis studies and homology modelling. Nevertheless it is still not fully understood how the enzyme catalyses the reaction. Because of the decisive role of OSC in cholesterol biosynthesis it represents a target for the discovery of novel anticholesteraemic drugs that could complement the widely used statins. Here we present two crystal structures of the human membrane protein OSC: the target protein with an inhibitor that showed cholesterol lowering in vivo opens the way for the structure-based design of new OSC inhibitors. The complex with the reaction product lanosterol gives a clear picture of the way in which the enzyme achieves product specificity in this highly exothermic cyclization reaction.
305 citations
TL;DR: Three oxidosqualene cyclase cDNAs were cloned from seedlings of Cucurbita pepo by homology based PCR method and demonstrated that CPQ and CPX encode cucurbitadienol and cycloartenol synthases, respectively.
93 citations
TL;DR: The correlation of analytical ultracentrifugation data and activity measurements showed the highest enzymatic activity for the monomeric hOSC indicating that this would be the natural form of OSC, and helped to identify the detergent for a successful crystallization of the protein.
49 citations
TL;DR: It is demonstrated that lack of the hydrophobic domains prevents at least in part the association of the proteins with lipid particles and causes their retention to the ER, which strongly supports the view that ER and lipid particles are related organelles.
46 citations
TL;DR: From a fungal strain FKI-0929, two compounds designated epohelmins A and B, were isolated as new natural products with inhibitory activity against recombinant human lanosterol synthase.
Abstract: From a fungal strain FKI-0929, two compounds designated epohelmins A and B, were isolated as new natural products with inhibitory activity against recombinant human lanosterol synthase. The crude extract from the whole broth of this strain was fractionated by silica gel column chromatography and HPLC to afford two isolated inhibitors. Detailed spectroscopic analyses led to the identification of their structures. They are diastereomers of 4,5-epoxy-2-(4'-oxoundec-(5'E)-enyl)-heptamethylenamines, and their relative stereochemical configurations were determined as (2R, 4R, 5R) or (2S, 4S, 5S) for epohelmin A, and (2R, 4S, 5R) or (2S, 4R, 5S) for epohelmin B, respectively. These compounds inhibited recombinant human lanosterol synthase with IC50 values of 10 and 6.0 microM, respectively.
20 citations
TL;DR: In this paper, an actinomycete strain, Streptomyces sp. K99-5041, was isolated as new natural products that inhibited the reaction of recombinant human lanosterol synthase.
Abstract: From an actinomycete strain, Streptomyces sp. K99-5041, lanopylins A1, B1, A2 and B2 were isolated as new natural products that inhibited the reaction of recombinant human lanosterol synthase. The crude extract from the whole broth of this strain was fractionated by silica gel column chromatography to afford an active fraction that showed a single spot on TLC. Detailed analyses of this fraction with liquid chromatography-atmospheric pressure chemical ionization mass spectrometry revealed that it contained 20 homologous compounds with differing side chain lengths. The fraction was separated by preparative HPLC to afford four of these homologues, lanopylins A1, B1, A2 and B2. Detailed spectroscopic analyses of these isolated compounds led to the identification of their structures. Lanopylins A1 and B1 were (3E)-isohexadecylmethylidene-2-methyl-1-pyrroline and (3E)-hexadecylmethylidene-2-methyl-1-pyrroline, respectively, and lanopylins A2 and B2 were homologues with the insertion of one cis-ethylenylidene in the side chain of lanopylins A1 and B1, respectively. These compounds inhibited recombinant human lanosterol synthase with IC50 values of 15, 18, 33, and 41μM, respectively.
2 citations
TL;DR: Three oxidosqualene cyclase cDNAs were cloned from seedlings of Cucurbita pepo by homology based PCR method and demonstrated that CPQ and CPX encode cucurbitadienol and cycloartenol synthases, respectively.
Abstract: Three oxidosqualene cyclase (OSC) cDNAs (CPX, CPQ, CPR) were cloned from seedlings of Cucurbita pepo by homology based PCR method. Their open reading frames were expressed in lanosterol synthase deficient (erg7) Saccharomyces cerevisiae strain GIL77. Analyses of in vitro enzyme activities and in vivo accumulated products in the transformants demonstrated that CPQ and CPX encode cucurbitadienol and cycloartenol synthases, respectively. These results indicated the presence of distinct OSCs for cycloartenol and cucurbitadienol synthesis in this plant.