chcr2083

Dr. Christoph Crocoll

   
   Department of Biochemistry
 Phone:-Max Planck Institute for Chemical Ecology
 Fax:-Hans-Knöll-Straße 8
  emailD-07745 Jena

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PhD Thesis

2011
Biosynthesis of the phenolic monoterpenes, thymol and carvacrol, by terpene synthases and cytochrome P450s in oregano and thyme
Friedrich-Schiller-Universität Jena, Biologisch-Pharmazeutische Fakultät
First Supervisor: Prof. Dr. J. Gershenzon
Co-Supervisor(s): Prof. Dr. J. Degenhardt

Abstract
Terpenes form the largest group of secondary metabolites with over 30.000 different structures. Despite their vast structural diversity, terpenes are formed from a simple five-carbon unit, isoprene diphosphate. Monoterpenes are formed from two and sesquiterpenes from three of these units, respectively. Two key biosynthetic steps determine most of the structural diversity. The first step is the conversion of the linear geranyl- and farnesyl diphosphates to the basic carbon skeletons of mono- and sesquiterpenes, respectively. This step often involves cyclization of the substrates and is catalyzed by the enzyme class of terpene synthases. The second step is the modification of these basic skeletons by hydroxylation, substitution or substraction. These modifications are highly specific to only a few terpenes and are catalyzed by several classes of enzymes. Origanum vulgare produces large amounts of mono- and sesquiterpenes in leaf glandular trichomes which have been implicated in the defense against herbivores. Some of these terpenes show secondary modifications and therefore provide an excellent system to study biosynthetic pathways. We identified six terpene synthases that produce almost the full terpene spectrum of the plant. The biosynthesis of the aromatic monoterpene alcohol thymol, proceeds over the olefin ?-terpinene that is subsequently oxidized to the aromatic p-cymene and hydroxylated to thymol. We currently identify and characterize the enzymes catalyzing the latter steps. The irregular C11 homoterpene DMNT is released by most plants after herbivore attack and might therefore provide an important function to the damaged plant. In maize, we determined that the biosynthesis of DMNT is formed from sesquiterpene nerolidol with a C15 skeleton and have genetic evidence that the substraction of four carbon atoms is catalyzed by two redundant genes.

Diploma Thesis

2004
Identification and biochemical characterization of terpene synthases from Origanum vulgare L.
Friedrich-Schiller-Universität Jena, Biologisch-Pharmazeutische Fakultät
First Supervisor: Prof. Dr. J. Gershenzon
Co-Supervisor(s): Prof. Dr. J. Degenhardt