title: 4-Hydroxybenzoate 3-geranyltransferase from Lithospermum erythrorhizon: purification of a plant membrane-bound prenyltransferase.
abstract: Geranyldiphosphate:4-hydroxybenzoate 3-geranyltransferase is a regulatory enzyme in the biosynthesis of shikonin, a phytoalexin and pharmaceutical produced by cell cultures of Lithospermum erythrorhizon Sieb. et Zucc. In Linsmaier-Skoog medium, the activity of this enzyme could be enhanced more than 200-fold by addition of methyl jasmonate, and this culture material was used for the solubilization and purification of the enzyme. Of various detergents examined, digitonin was the most suitable for the solubilization of the enzyme. The solubilized enzyme was purified 800-fold by chromatography over diethylaminoethyl (DEAE)-Sephacel, Heparin-Sepharose, Reactive Green 19-Agarose, and Cholic Acid-Agarose. The purified enzyme required magnesium ions as cofactor and was highly specific for geranyldiphosphate (GPP) and 4-hydroxybenzoate (4HB) as substrates. The K(m) values for 4HB and GPP were calculated by the method of Lineweaver and Burk as 18.4 microM and 13.8 microM, respectively.
authors.affiliation: Pharmazeutisches Institut, Pharmazeutische Biologie, Eberhard-Karls-Universität Tübingen, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Mühlenweg
authors.forename: M
authors.initials: M
authors.lastname: Melzer
authors.forename: S M
authors.initials: SM
authors.lastname: Li
authors.forename: L
authors.initials: L
authors.lastname: Heide
mesh_terms: D000085:Acetates; D019883:Alkyl and Aryl Transferases / Q000302:isolation & purification / Q000378:metabolism*; D002478:Cells, Cultured; D003517:Cyclopentanes; D004072:Digitonin; D004122:Dimethylallyltranstransferase / Q000302:isolation & purification / Q000378:metabolism*; D051228:Geranyltranstransferase; D006863:Hydrogen-Ion Concentration; D008274:Magnesium; D008565:Membrane Proteins / Q000302:isolation & purification / Q000378:metabolism*; D054883:Oxylipins; D010944:Plants / Q000201:enzymology*; D012995:Solubility; D013379:Substrate Specificity; D013696:Temperature
chemical_list: D000085:Acetates; D003517:Cyclopentanes; D008565:Membrane Proteins; D054883:Oxylipins; C072239:methyl jasmonate; D019883:Alkyl and Aryl Transferases; D004122:Dimethylallyltranstransferase; D051228:Geranyltranstransferase; D008274:Magnesium; D004072:Digitonin