Showing papers on "Lanosterol synthase published in 2005"
TL;DR: Efforts to modify the catalytic specificity of enzymes consistently show that it is easier to broaden the substrate or product specificity of an accurate enzyme than to restrict the selectivity of one that is promiscuous.
Abstract: Efforts to modify the catalytic specificity of enzymes consistently show that it is easier to broaden the substrate or product specificity of an accurate enzyme than to restrict the selectivity of one that is promiscuous. Described herein are experiments in which cycloartenol synthase was redesigned to become a highly accurate lanosterol synthase. Several single mutants have been described that modify the catalytic specificity of cycloartenol to form some lanosterol. Modeling studies were undertaken to identify combinations of mutations that cooperate to decrease the formation of products other than lanosterol. A double mutant was constructed and characterized and was shown to cyclize oxidosqualene accurately to lanosterol (99%). This catalytic change entailed both relocating polarity with a His477Asn mutation and modifying steric constraints with an Ile481Val mutation.
59 citations
TL;DR: The ability of C. glabrata to replace ergosterol with host sterol may be responsible for its elevated azole resistance.
51 citations
TL;DR: Examination of activity variation among eight taro cultivars indicated that "Aichi-wase" and "Yatsugashira" had the most potent activity for hOSC inhibition.
Abstract: Ethanol extracts of lyophilized vegetables were tested for inhibition of human lanosterol synthase (hOSC) in order to find the compounds to suppress cholesterol biosynthesis Of 130 samples tested, twelve samples showed significant inhibition Among them, Colocasia esculenta (taro) showed the highest inhibition (55% inhibition at 300 microg/ml) Examination of activity variation among eight taro cultivars indicated that "Aichi-wase" and "Yatsugashira" had the most potent activity for hOSC inhibition In order to identify the active constituent of taro, ethanol extracts of "Aichi-wase" were partitioned with hexane and aqueous methanol, and fractionated by silica gel column chromatography Inhibitory activity was concentrated in two major active fractions Further purification of these fractions by preparative HPLC gave three monogalactosyldiacylglycerols and five digalactosyldiacylglycerols as active compounds that showed 28 to 67% inhibitory activities at the concentration 300 microg/ml
35 citations
TL;DR: The findings demonstrate that T. cruzi can specifically regulate gene expression in response to derangements in its cellular functions, and that sterol biosynthesis enzymes can be controlled through the 3'-untranslated region of the gene.
27 citations
TL;DR: Digalactosyl and monogalactocyl diacylglycerols (DGDG and MGDG), which were identified as anti-hyperlipemia active components in Colocasia esculenta (Taro), were synthesized and showed the most potent activity.
25 citations
TL;DR: Results indicate that exit of lanosterol from LP occurs independently of functional Erg11p, random supply of sterol intermediates to all organelles of erg11Delta erg3Delta appears to compensate for the lack of ergosterol in this mutant, and preferential sorting of ergostol in wild type, but also of ergosta-7,22-dienol in erg3 Delta, supplies sterol to the plasma membrane.
24 citations
TL;DR: Crystal structure and homology modelling indicate that both enzymes possess a narrow constriction that separates an entrance lipophilic channel from the active-site cavity of squalene-hopene cyclase from Alicyclobacillus acidocaldarious and lanosterol synthase from Saccharomyces cerevisiae.
Abstract: Substrate access to the active-site cavity of squalene-hopene cyclase from Alicyclobacillus acidocaldarious and lanosterol synthase [OSC (oxidosqualene cyclase)] from Saccharomyces cerevisiae was studied by an inhibition, mutagenesis and homology-modelling approach. Crystal structure and homology modelling indicate that both enzymes possess a narrow constriction that separates an entrance lipophilic channel from the active-site cavity. The role of the constriction as a mobile gate that permits substrate passage was investigated by experiments in which critically located Cys residues, either present in native protein or inserted by site-directed mutagenesis, were labelled with specifically designed thiol-reacting molecules. Some amino acid residues of the yeast enzyme, selected on the basis of sequence alignment and a homology model, were individually replaced by residues bearing side chains of different lengths, charges or hydrophobicities. In some of these mutants, substitution severely reduced enzymatic activity and thermal stability. Homology modelling revealed that in these mutants some critical stabilizing interactions could no longer occur. The possible critical role of entrance channel and constriction in specific substrate recognition by eukaryotic OSC is discussed.
10 citations
TL;DR: The structures of epohelmins A and B isolated as lanosterol synthase inhibitors from a fungal strain FKI-0929 were revised to be 1α-hydroxy-3α-(4′-oxoundec-(5′E)-enyl)-pyrrolizidine and 1β-hydroxymethicone, respectively, by comparison with spectral data of synthetic compounds.
Abstract: Revised Structures of Epohelmins A and B Isolated as Lanosterol Synthase Inhibitors from a Fungal Strain FKI-0929
8 citations
TL;DR: The results suggest that the fungicidal activity of these inhibitors is related to their inhibitory effect on LS, and its use for screening molecules to find fungal inhibitors is described.
4 citations
TL;DR: In this article, two compounds designated epohelmins A and B were isolated as new natural products with inhibitory activity against recombinant human lanosterol synthase, and their relative stereochemical configurations were determined as (2R, 4R, 5R) or (2S, 4S, 5S) for epohelmin A, and (2 R, 4 S, 6.0 microM for ephelmin B, respectively.
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.
3 citations