Ornithine-containing Lipid Research Articles

The Identification of cis-11,12-Methylene-2-hydroxyoctadecanoic Acid from Thiobacillus thiooxidans

Abstract 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 14C-labeling 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-11,12-methylene-2-hydroxyoctadecanoic acid.

Isolation of an ornithine-containing lipid from Thiobacillus thiooxidans.

The ornithine-containing lipid was separated from the other lipids of Thiobacillus thiooxidans by thin-layer chromatography. The aminolipid possesses both amide and ester linkages.

Studies on the cell walls of pseudomonas species resistant to ethylenediaminetetra-acetic acid.

SUMMARY: Cell walls were prepared from various species of the genus Pseudomonas which are resistant to ethylenediaminetetra-acetic acid (EDTA). The cell walls were analysed and comparisons made with the walls of EDTA-sensitive pseudomonads. The walls had none of the structural features which appeared to characterize EDTA-sensitive pseudomonads. Lipopolysaccharide was not extracted from the walls of resistant organisms by EDTA at pH 9.2. The wall of P. iodinum contained almost no lipid or protein but consisted mainly of glycosaminopeptide and material which resembled a teichoic acid. It is proposed that this organism be removed from the genus Pseudomonas. The walls of P. diminuta, P. maltophilia, P. pavonacea and P. rubescens had compositions broadly characteristic of Gram-negative bacteria. The four species are not obviously related. Glycolipids were present in the walls of P. diminuta, P. maltophilia and P. rubescens. An ornithine-containing lipid was isolated from P. rubescens and partly characterized. A small amount of this lipid was also present in P. maltophilia. The wall of P. maltophilia was distinctive in its wide range of monosaccharide components, including an unidentified neutral sugar of high mobility on paper chromatograms.

Studies on the structure of an ornithine-containing lipid from non-sulphur purple bacteria

A new type of lipid which contains l-ornithine has been found in Rhodopseudomonas spheroides and in other non-sulphur purple bacteria. Its properties, as far as they have been determined, are consistent with the structure: H 2N β [CH 2] 3 β CH(NH β CO β R 1) β CO β O β R 2, where R 1 is either a C 16 or C 18 fatty acid residue and R 2 is a higher alcohol with a C-methyl group or a cyclopropane ring. The compound is likely to have a structural role within the cytoplasmic membrane system of non-sulphur purple bacteria.

Ornithine-containing lipid in Rhodospirillum rubrum

An ornithine-containing lipid that lacks phosphorus has been observed in Rhodospirillum rubrum. [ 14C]Omithine is incorporated into lipid during growth. Formation of ornithine lipid does not seem to be related to the synthesis of bacteriochlorophyll. Arginine repressed the formation of the ornithine lipid, but at the same concentration it repressed ornithine transcarbamylase twice as much.