25th International Meeting on Organic Geochemistry IMOG 2011

O-51
Role of biosynthesis leading to the saw-toothed profile in δ13C
and δ2H of n-alkanes and systematic isotopic differences
between n-, iso- & anteiso-alkanes in leaf waxes of land plants
Youping Zhou 1,2 , Kliti Grice 1 , Hilary Stuart_Williams 2 , Graham Farquhar 2 , Charles
Hocart 2
1 Curtin University, Perth, Australia, 2 Australian National University, Canberra, Australia (corresponding
author:y.zhou@curtin.edu.au)
The n-fatty acids containing an even number of
carbons (ECN-n-FAs) in higher plants are synthesised
by repetitive addition of a 2 carbon unit from malonyl-
CoA (synthesised from acetyl CoA which is in turn
derived from pyruvate). The n-alkanes containing an
odd number of carbons (OCN-n-alkanes) are
generally formed by the decarboxylation of ECN-n-
FAs, but it is unknown how the less abundant evencarbon-numbered
alkanes (ECN-n-alkanes) are
biosynthesised in higher plants [1,3,4] .
We have observed a distinctive compositional pattern
of incorporation of stable carbon ( 13 C) and hydrogen
( 2 H) isotopes in co-existing ECN- and OCN-n-alkanes
in leaves of higher plants, such that the OCN nalkanes
are more enriched in 13 C but more depleted
in 2 H than the ECN-n-alkanes [2,7] .
� 13 COCN-n-alkanes>� 13 CECN-n-alkanes
� 2 HOCN-n-alkanes