Compound-specific carbon and hydrogen isotopic compositions of lipid biomolecules (n-alkanes, n-alkanoic acids, n-alkanols, sesquiterpenes, diterpenes, phytol, diterpenols and β-sitosterol), extracted from Cryptomeria japonica leaves, were determined in order to understand isotopic fractionations occurring during lipid biosynthesis in this species. All lipid biomolecules were depleted in both 13C and D relative to bulk tissue and ambient water, respectively. n-Alkyl lipids associated with the acetogenic pathway were depleted in 13C relative to bulk tissue by 2.4-9.9‰ and depleted in D relative to ambient water by 91-152‰. C15- and C30-isoprenoid lipids (sesquiterpenes, squalene and β-sitosterol) associated with the mevalonic-acid pathway are depleted in 13C relative to bulk tissue by 1.7-3.1‰ and depleted in D relative to ambient water by 212-238‰. C20-isoprenoid lipids (phytol and diterpenoids) associated with the non-mevalonic-acid pathway were depleted in 13C relative to bulk tissue by 4.6-5.9‰ and depleted in D relative to ambient water by 238-303‰. Phytol was significantly depleted in D by amounts up to 65‰ relative to other C 20 isoprenoid lipids. The acetogenic, mevalonic-acid and non-mevalonic-acid pathways were clearly discriminated using a cross-plot between the carbon and hydrogen isotopic fractionations.
All Science Journal Classification (ASJC) codes
- Molecular Biology
- Plant Science