title: Alkanes are not innocuous vehicles for hydrophobic reagents in membrane studies.
abstract: Alkanes (C6-C16) are often used as vehicles for hydrophobic reagents, e.g. long-chain ceramides, in cell biology studies. It is generally understood that they are inert solvents, particularly when added in small volumes. However, simple calculations show that, under standard experimental conditions in cell studies, alkane: phospholipid molar ratios in excess of 1000:1 may be found. Even at much smaller ratios (close to 1:1) our studies with liposomes show that alkanes induce vesicle aggregation. Differential scanning calorimetry shows marked changes in both the gel-fluid and the lamellar-hexagonal transitions. Alkanes inhibit bacterial sphingomyelinase when acting on large unilamellar vesicles, and activate bacterial phospholipase C under the same conditions. Thus, the use of alkanes in cell studies requires strict control experiments to avoid artefactual results.
authors.affiliation: Unidad de Biofísica (Centro Mixto CSIC-UPV/EHU), and Departamento de Bioquímica, Universidad del País Vasco, Aptdo. 644, 48080 Bilbao, Spain.
authors.forename: Patricia
authors.initials: P
authors.lastname: Urbina
authors.forename: Alicia
authors.initials: A
authors.lastname: Alonso
authors.forename: F-Xabier
authors.initials: FX
authors.lastname: Contreras
authors.forename: Félix M
authors.initials: FM
authors.lastname: Goñi
authors.forename: David J
authors.initials: DJ
authors.lastname: López
authors.forename: L-Ruth
authors.initials: LR
authors.lastname: Montes
authors.forename: Jesús
authors.initials: J
authors.lastname: Sot
mesh_terms: D000473:Alkanes / Q000737:chemistry* / Q000494:pharmacology*; D002152:Calorimetry, Differential Scanning / Q000379:methods; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D008567:Membranes, Artificial; D012680:Sensitivity and Specificity; D013108:Sphingomyelin Phosphodiesterase / Q000037:antagonists & inhibitors / Q000737:chemistry; D013696:Temperature; D013997:Time Factors; D010738:Type C Phospholipases / Q000737:chemistry / Q000187:drug effects
chemical_list: D000473:Alkanes; D008567:Membranes, Artificial; D010738:Type C Phospholipases; D013108:Sphingomyelin Phosphodiesterase