A polar fatty acid has been observed as a component of an
ornithine-containing lipid of Thiobacillus thiooxidans. A
comparison of thin layer chromatographic mobilities of reference
compounds to those of the natural acid and its derivatives
suggested that the acid was a 2-hydroxy fatty acid.
The presence of a cyclopropane function in the acid was
indicated by l4e-Iabeling experiments and infrared spectroscopy.
Mass spectrometry of the methyl ester and the acetylated
methyl ester of the natural acid provided a molecular
weight for the acid. Equivalent chain lengths were determined
for the natural acid, the acid obtained by oxidative
decarboxylation of the natural acid with permanganate, and
the acids derived through reductive ring cleavage of the
cyclopropane group in the ester of the oxidatively decarboxylated
natural acid. The mass spectral data, the equivalent
chain length determinations, and the permanganate oxidation
study clearly indicated that the acid possessed an 18-
carbon chain with a methylene bridge and a 2-hydroxyl
function. The equivalent chain length determinations
further suggested that the cyclopropane group had the cis
configuration. Mass spectrographic analysis of the branched
chain esters obtained by reductive cleavage of the ester
which was in turn derived through oxidative decarboxylation
of the natural acid allowed the assignment of the 11,12
position for the cyclopropane group. Based on these data,
the polar acid is proposed to be cis-ll, 12-methylene-2-
hydroxyoctadecanoic acid
