Solubility /
Solution Stability: |
Organic Solvents: Product is soluble in
chloroform at all concentrations.
Saturated analogs are more difficult to solubilize in organic solvents.
Solubility of saturated analogs in chloroform is enhanced by adding
small
amounts of alcohol and water (to obtain a concentration of 10mg/ml
saturated
LPA in chloroform add 1.2% methanol and 0.6% water relative to chloroform
volume) |
Biologically
Compatible
Solvents: |
Solubility in biologically compatible
solvents such as dimethylsulfoxide (DMSO) or ethanol is limited. Product
is
completely soluble in ethanol:water (1:1, v/v), although heating and
sonication may be necessary to disperse. Product is only partially
soluble
at higher ethanol content. Solubility in water (buffer) is limited
to
concentrations below the CMC of the molecule. In order to obtain maximum
interaction with biological systems at concentrations above the CMC
it is
necessary to reduce the particle size of the micelle by sonication
or
absorption of the LPA to fatty acid serum albumin (BSA). LPA's bound
to fatty acid free
albumin will appear as clear solutions. Solution has been achieved
in
phosphate buffered saline (PBS), pH 7.2, at up to 0.3 mM (0.14 mg per
ml) in
the presence of 0.1% (w/v) bovine serum albumin (essentially fatty
acid
free).
Note: Absorption of dilute stock solutions to plastic and glass
can be a
serious source of variation. Approximately 75% of a 5uM stock solution
was found to stick tightly to the
wall of an Eppendorf vial within 30 minutes. |
| Storage: |
LPA should be stable in organic or aqueous solution at neutral
conditions. Freezer storage (-20°C) is recommended for organic
solutions
(including ethanol:water, 1:1), while aqueous preparations (stable
for 24-48
hours) should be stored refrigerated (4°C). Partial acyl migration
from the
gamma (1) position to the beta (2) position may be possible under certain
non-neutral conditions, such as those stimulating the formation of
an
equilibrium mixture of 1,2 and 1,3-diglycerides in acidic or basic
solution.
Oxidation of the fatty acid double bond may occur if submitted to oxidizing
conditions. Maintaining the product under an inert atmosphere (nitrogen
or
argon) may be appropriate for some applications. |
Biological
responses to LPA |
- Cell Proliferation
- Inhibition of differentiation
(neuroblastoma cells, myoblasts)
- Platelet aggregation
- Smooth muscle contraction
- Neurotransmitter release
- Stress fibre formation/cell rounding/neurite retraction
- Cell-surface-fibronectin binding
- Tumor cell invasion
- Chemotaxis (dictyostelium amoebae)
- Cl--mediated membrane depolarization (fibroblasts)
- Inhibition of connexin 43 based cell-cell communication
- Increased tight junction permeability
(brain endothelial cells)
|
| Note: The bioactivity of LPA appears
to require long (i.e., C16 to C18) acyl carbon chains of the type
usually found associated with membrane lipids although optimum requirements
for a single type of acyl carbon chain are not universal. The bioactivity
decreases with shorter chain length. In serum, oleoyl and palmitoyl
fatty acid containing LPA are the predominant species. |
Reference:
Moolenaar, Wouter H.; Kranenburg, Onno; Postma,
Friso R.; Zondag, Gerben C.M.: (1997), "Lysophosphatidic acid:
G-protein signaling and cellular responses." Curr. Opin.
Cell Biol. 9:168-173 |
