What Is 16:0-18:1 Cardiolipin?

Cardiolipin (CL) is a unique dimeric phospholipid composed of two phosphatidylglycerol units linked by a central glycerol backbone, giving it four acyl chains and two phosphate head groups. This distinctive architecture makes cardiolipin the only known bis-phospholipid found in significant quantities in mammalian cells, where it is almost exclusively concentrated in the inner mitochondrial membrane (IMM).

16:0-18:1 Cardiolipin is a defined, synthetic variant in which the four acyl positions are occupied by palmitoyl (16:0, saturated) and oleoyl (18:1 Δ9, monounsaturated) chains in an asymmetric configuration. Unlike the predominant natural cardiolipin species in heart tissue—which is enriched in linoleoyl (18:2) chains—this mixed-chain species offers researchers a chemically tractable tool to dissect the specific roles of acyl chain saturation and asymmetry in cardiolipin function.

The compound is supplied by Aladdin Scientific under SKU C1439493 and is intended for in vitro research use only.

Biochemical Properties and Structural Significance

The molecular architecture of cardiolipin—particularly its cone-shaped geometry arising from the bulky four-acyl-chain body and small head group—promotes negative membrane curvature. This property is critical for the formation and stabilization of the highly folded IMM cristae, which house the electron transport chain (ETC) complexes and ATP synthase.

The 16:0-18:1 species introduces one degree of unsaturation per oleoyl chain, resulting in a membrane fluidity profile intermediate between fully saturated and polyunsaturated cardiolipin species. This makes it particularly valuable for controlled biophysical studies examining how chain unsaturation influences:

• Membrane bilayer fluidity and phase behavior
• Curvature stress and cristae morphology
• Cardiolipin–protein interactions (e.g., cytochrome c, respiratory supercomplexes)

Additionally, cardiolipin carries two phosphomonoester groups with pKa values reported in the range of approximately 2.8 and 7.5–9.5, making it predominantly anionic at physiological pH. This anionic character is essential for electrostatic interactions with positively charged residues on mitochondrial proteins.

Research Applications

16:0-18:1 Cardiolipin is employed across a range of experimental contexts where a chemically defined, asymmetric CL species is required:

Mitochondrial Membrane Reconstitution

Researchers use defined CL species to reconstitute proteoliposome systems that recapitulate the lipid environment of the IMM. Using 16:0-18:1 CL allows precise control of acyl chain composition, enabling mechanistic studies of respiratory complex assembly and activity independent of the variable CL composition found in native membranes.

Apoptosis and Cytochrome c Release Studies

Cardiolipin plays a pivotal role in the early stages of intrinsic apoptosis, acting as a docking site for cytochrome c on the IMM. Oxidation of cardiolipin by reactive oxygen species (ROS) promotes cytochrome c detachment and subsequent release into the cytosol. 16:0-18:1 CL provides a well-defined substrate for studying these oxidation events and their downstream consequences in cell-free or reconstituted systems.

Lipid–Protein Interaction Assays

Defined CL species are used in surface plasmon resonance (SPR), native mass spectrometry, and lipid overlay assays to characterize binding affinities and stoichiometries between cardiolipin and mitochondrial proteins such as ANT (adenine nucleotide translocator), VDAC, and the respiratory supercomplexes.

Liposome and Model Membrane Preparation

16:0-18:1 CL is incorporated into large unilamellar vesicles (LUVs) and supported lipid bilayers (SLBs) to model the IMM environment for biophysical measurements including fluorescence polarization, differential scanning calorimetry (DSC), and atomic force microscopy (AFM).

Handling, Storage, and Quality Considerations

As with all polyunsaturated and monounsaturated phospholipids, 16:0-18:1 Cardiolipin is susceptible to oxidative degradation. To maintain product integrity, the following practices are recommended:

• Storage: Store under inert gas (argon or nitrogen) at −20 °C or below. Avoid repeated freeze-thaw cycles.
• Solvent: The compound is typically supplied dissolved in chloroform or chloroform/methanol. Work in a fume hood and use glass syringes to prevent solvent absorption into plastic.
• Handling: Minimize exposure to light, heat, and atmospheric oxygen. Aliquot into single-use portions upon first opening.
• Quality verification: Researchers requiring confirmation of acyl chain integrity and oxidation status should perform thin-layer chromatography (TLC) or LC-MS analysis prior to use in sensitive assays.

This product is intended for research use only and is not suitable for diagnostic, therapeutic, or food applications.