Phospholipid lateral organization in synthetic membranes as monitored by pyrene-labeled phospholipids: effects of temperature and prothrombin fragment 1 binding

Abstract

Pyrene-labeled phospholipids have been used to test for the existence of lateral domains due to temperature-induced phase separations and binding of prothrombin fragment 1 to charged lipid vesicles. When in close proximity, pyrene-containing probes can exchange excited-state energy to form excimers; the ratio of the excimer to monomer fluorescence intensity (E/M) is proportional to the local concentration of probe in the membranes, as well as to the excimer lifetime and the probe's lateral diffusion coefficient. The ability of the pyrene-labeled phospholipids to quantitatively report the coexistence of multiple environments was demonstrated in dipalmitoylphosphatidylcholine/palmitoyloleoylphosphatidylcholine multilamellar vesicle preparations of varying compositions, each of which contained coexisting fluid and gel phases. In this system, pyrene-labeled phosphatidylcholine was found to favor the fluid relative to the gel phase with a partition coefficient of 7. At 37 degrees C, in dioleoylphosphatidylglycerol (DOPG)/palmitoyloleoylphosphatidylcholine (POPC) large, unilamellar vesicles containing either pyrene-labeled phosphatidylglycerol (py-PG) or pyrene-labeled phosphatidylcholine (py-PC), the excimer lifetime (37 ns) and the lateral diffusion constant of the probe (5.8 X 10(-8) cm2/s) were independent of the membrane composition and the presence of fragment 1 and Ca2+. Consequently, E/M was directly proportional to only the local concentration of the py-PG or py-PC probes. When saturating amounts of fragment 1 and 5 mM Ca2+ were added to DOPG/POPC vesicles that contained either probe, no change in E/M and hence the local probe concentration was observed.(ABSTRACT TRUNCATED AT 250 WORDS)

Intermolecular interactions of lysobisphosphatidic acid with phosphatidylcholine in mixed bilayers

“…This reflects increased lateral diffusion of the probe as the temperature is increased thus enhancing the collisional frequency leading to increased I e /I m values. Similar behavior has been observed for instance for fluid POPC vesicles as the temperature is increased (Jones and Lentz, 1986). A monotonous increase in I e /I m is also observed for bisPDPC (X = 0.001) residing in pure LBPA 18:1 vesicles as the temperature is increased.…”

Phosphatidylethanolamine and phosphatidylglycerol are segregated into different domains in bacterial membrane. A study with pyrene‐labelled phospholipids

“…The probe mole fraction of total membrane lipids can be estimated as 1–5% from the known cell mass in a sample and chemical composition of an average E. coli cell (Neidhardt and Umbarger, 1966). This estimation is validated by the similar values of excimer‐to‐monomer ratio at the same mole fractions of pyrene‐phospholipid in liposomes (Jones and Lentz, 1986).…”

“…This value seems to be reliable, because the ratio I Ex /I M in bacterial membranes (from 0.1 to 0.4, Fig. 4) is close to that reported for liposomes labelled at the same probe mole fraction (Jones and Lentz, 1986). In addition, the localization of fluorescent phospholipids in the plasma membrane was microscopically visualized using rhodamine labelled phopholipids (Fig.…”

Fluorescent Analogs of Biomolecular Building Blocks: Design, Properties, and Applications

“…Examples include: DPH-PC ( 4.19 ),188 Anthr-PC ( 4.20 ),189–191 Pyrene-PC ( 4.21 ),8,184,192 and NBD-PC ( 4.22 ) 193. Due to its polarity sensitive emission maximum and high quantum yields, NBD labeled probes are often used to assess location within membranes 180.…”