Branched Lipids

Iso- and anteiso-branched lipids are found in the cytoplasmic membranes of bacteria. For many bacterial species, branched-chain lipids compose more than 20% of the total cellular lipids, and these branched-chain lipids are thought to be important in maintaining membrane fluidity. Studies have shown that the transition enthalpies of anteiso-branched PC lipids are smaller/lower than for the straight-chain equivalent PC lipids, providing evidence that membranes containing a high degree of anteiso-branched PC lipids are more likely to be in a disordered gel phase than membranes containing a high degree of equivalent straight-chain PC lipids. In contrast, iso-branched PC lipids exhibited transition enthalpies comparable to the equivalent straight-chain PC lipids. Differing lipid acyl chain structures and compositions is proving to be incredibly significant in determining bacterial response to antimicrobial agents.

References:

Kaneda T. Iso- and anteiso-fatty acids in bacteria: biosynthesis, function, and taxonomic significance. Microbiol Rev. 1991 Jun;55(2):288-302. PMID: 1886522.

Mitchell NJ, Seaton P, Pokorny A. Branched phospholipids render lipid vesicles more susceptible to membrane-active peptides. Biochim Biophys Acta. 2016 May;1858(5):988-94. doi: 10.1016/j.bbamem.2015.10.014. PMID: 26514602.