Conformational Analysis, Thermal Rearrangement, and EI-MS Fragmentation Mechanism of (1(10)E,4E,6S,7R)-Germacradien-6-ol by (13)C-Labeling Experiments

Angew Chem Int Ed Engl. 2015 Nov 2;54(45):13448-51. doi: 10.1002/anie.201507615. Epub 2015 Sep 11.

Abstract

An uncharacterized terpene cyclase from Streptomyces pratensis was identified as (+)-(1(10)E,4E,6S,7R)-germacradien-6-ol synthase. The enzyme product exists as two interconvertible conformers, resulting in complex NMR spectra. For the complete assignment of NMR data, all fifteen ((13)C1)FPP isotopomers (FPP=farnesyl diphosphate) and ((13)C15)FPP were synthesized and enzymatically converted. The products were analyzed using various NMR techniques, including (13)C, (13)C COSY experiments. The ((13)C)FPP isotopomers were also used to investigate the thermal rearrangement and EI fragmentation of the enzyme product.

Keywords: NMR spectroscopy; conformation analysis; isotopic labeling; mass spectrometry; terpenoids.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alkyl and Aryl Transferases / chemistry
  • Alkyl and Aryl Transferases / metabolism*
  • Carbon Isotopes
  • Carbon-13 Magnetic Resonance Spectroscopy
  • Molecular Conformation
  • Polyisoprenyl Phosphates / chemical synthesis
  • Polyisoprenyl Phosphates / chemistry
  • Sesquiterpenes / chemical synthesis
  • Sesquiterpenes / chemistry
  • Sesquiterpenes, Germacrane / chemistry*
  • Sesquiterpenes, Germacrane / metabolism
  • Spectrometry, Mass, Electrospray Ionization
  • Temperature*

Substances

  • Carbon Isotopes
  • Polyisoprenyl Phosphates
  • Sesquiterpenes
  • Sesquiterpenes, Germacrane
  • farnesyl pyrophosphate
  • Alkyl and Aryl Transferases