Biochemistry, Department of


Date of this Version



The Journal of Biological Chemistry, Vol. 244, No. 17, Issue of September 10, pp. 4773-4778, 1969


Used by permission.


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.