title: Impact of free hydroxylated and methyl-branched fatty acids on the organization of lipid membranes.
abstract: Differential scanning calorimetry (DSC) has been applied to study the effect of free hydroxylated and methyl-branched fatty acids on the physico-chemical properties of lipid membranes. First, the impact of free hydroxy fatty acids (HFAs) on dimyristoylphosphatidylcholine (DMPC) model membranes was monitored only as a function of chain length and position of the attached hydroxyl group. Second, racemic vs. enantiopure anteiso fatty acids (AFAs) and HFAs were investigated to address the question of which role does a fatty acid's chirality play on its membrane pertubing effect. The DSC thermograms revealed that the main gel to liquid-crystalline phase transition of the DMPC bilayers which results in a disordering effect of the lipid hydrocarbon chains was affected in different ways depending on the nature of the incorporated fatty acid. Long-chain 2- and 3-HFAs stabilized the gel phase by reducing the phase transition temperature (T(m)), whereas short-chain HFAs and long-chain HFAs with the hydroxy group remote from the head group stabilized the more disordered liquid-crystalline state. Additionally, we observed that enantiopure (S)-14-methylhexadecanoic acid ((S)-a17:0) and (R)-2-hydroxy octadecanoic acid and the corresponding racemates had contrary effects upon incorporation into DMPC bilayers. In both cases, the pure enantiomers alleviated the liquid-crystalline state of the biological model membrane.
authors.affiliation: Institute of Food Chemistry, University of Hohenheim, Garbenstrasse 28, D-70599 Stuttgart, Germany.
authors.forename: Ramona
authors.initials: R
authors.lastname: Jenske
authors.forename: Fredrick
authors.initials: F
authors.lastname: Lindström
authors.forename: Gerhard
authors.initials: G
authors.lastname: Gröbner
authors.forename: Walter
authors.initials: W
authors.lastname: Vetter
mesh_terms: D002152:Calorimetry, Differential Scanning; D002462:Cell Membrane / Q000737:chemistry / Q000378:metabolism; D004134:Dimyristoylphosphatidylcholine / Q000737:chemistry* / Q000378:metabolism; D005227:Fatty Acids / Q000737:chemistry* / Q000378:metabolism; D006880:Hydroxy Acids / Q000737:chemistry* / Q000378:metabolism; D008051:Lipid Bilayers / Q000737:chemistry* / Q000378:metabolism; D015394:Molecular Structure; D010169:Palmitic Acids / Q000737:chemistry / Q000378:metabolism; D044367:Phase Transition; D013237:Stereoisomerism; D013696:Temperature
chemical_list: D005227:Fatty Acids; D006880:Hydroxy Acids; D008051:Lipid Bilayers; D010169:Palmitic Acids; C046143:14-methylhexadecanoic acid; D004134:Dimyristoylphosphatidylcholine