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.

Conversion of a plant oxidosqualene-cycloartenol synthase to an oxidosqualene-lanosterol cyclase by random mutagenesis

Abstract: A random mutagenesis/in vivo selection approach was applied to generate and identify mutations that alter the product specificity of oxidosqualene-cycloartenol synthase (CAS) from Arabidopsis thaliana This work complements previous studies of triterpene cyclase enzymes and was undertaken to provide knowledge of the frequency and locations at which point mutations can alter cyclase product specificity Random mutations were introduced by treatment with hydroxylamine or passage through a mutator strain of bacteria Libraries of mutated plasmids carrying the cas1 gene were transformed into a cyclase-deficient strain of Saccharomyces cereVisiae (CBY57) bearing a complementing plasmid (pZS11) carrying an Erg7 gene that encodes wild-type yeast oxidosqualene-lanosterol cyclase and a URA3 marker that could be counterselected by growth in media containing 5-fluoroorotic acid (5-FOA) This allowed use of a plasmid shuffle to select for cas1 mutants that could substitute for ERG7 activity Five of 73000 transformants were observed to grow in media containing 5-FOA but lacking ergosterol pTKP5-derived plasmids isolated from these transformants were sequenced, revealing five distinct and unique point mutations: Tyr410Cys, Ala469Val, His477Tyr, Ile481Thr, and Tyr532His Analysis of the nonsaponifiable lipids from CBY57 cells expressing these mutants suggests that the Tyr410Cys and His477Tyr mutants produce lanosterol as the dominant product, whereas the Ala469Val, Ile481Thr, and Tyr532His mutants produce a mixture of lanosterol and achilleol A, a product of monocyclization Sequence and structural homology modeling of CAS indicate that the observed product specificity-altering mutations occur both within (Tyr410Cys, Ile481Thr, and Tyr532His) and outside of (Ala469Val and His477Tyr) the cyclase active site

Nonpolar components of the latex of Euphorbia peplus

Abstract: The less polar fractions of the latex of Euphorbia peplus were found to contain obtusifoliol, cycloartenol, 24-methylenecycloartanol, lanosterol, and 24-methylenelanosterol in the free and esterified triterpene alcohol fractions; 9-cis-tricosene as the major component of the hydrocarbon fraction; and a new acyclic triterpene alcohol named peplusol (1). The structure of 1 was determined as the R-isomer of (all-E)-2-(5,9-dimethyl-1-methylene-4,8-decadienyl)-5,9,13-trimethyl-4,8,12-tetradecatrien-1-ol by spectral and chemical methods.

Purification and properties of cytochrome P-450-dependent 14 alpha-sterol demethylase from Candida albicans.

Abstract: The purification of cytochrome P-450-dependent 14 alpha-sterol demethylase (P-450DM) from the important opportunistic fungal pathogen, Candida albicans, is described. Optimal purification (875-fold) was achieved by extracting the cytochrome from microsomes with sodium cholate followed by hydroxyapatite, octyl-Sepharose and CM-Sepharose chromatographies, giving a cytochrome preparation of 17.5 nmol/mg of protein. By the use of SDS/polyacrylamide-gel electrophoresis the cytochrome was judged to be highly purified on the basis of Coomassie Brilliant Blue staining of protein. The Mr of P-450DM was estimated to be 51,000. The absorption spectrum of oxidized P-450DM was characteristic of a low-spin cytochrome, and its reduced CO complex had a Soret absorption peak at 447 nm. When reconstituted in a model membrane system of dilauroylphosphatidylcholine with NADPH and O2, P-450DM catalysed the complete 14 alpha-demethylation of lanosterol, which was inhibited by CO. The cytochrome appeared to have a high degree of substrate specificity; it was unable to oxidize a number of xenobiotic compounds in the reconstituted assay.