Mixed Monolayers Containing Phosphatidylcholine, Cholesterol, Oleic Acid, and Mono- and Triolein.

Lundberg, Bo; Ekman, Stig; Rämsby, S.; Stjernström, Nils E.; Enzell, Curt R.; Reid, William W.; Yanaihara, Noboru; Yanaihara, Chizuko

doi:10.3891/acta.chem.scand.33b-0395

Cited by 12 publications

(14 citation statements)

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“…From studies of ester substrate hydrolysis, we have suggested that the critical transition of substrate utilization in monolayers reflects a lipid organizational transition from a phosphatidylcholine-dominated to a substrate-dominated surface (Muderhwa & Brockman, 1990) in a manner consistent with percolation theory (Brockman & Muderhwa, 1991). The data of Figure 5 show that throughout the compositional range of the critical transition for DA oxygen exchange, the mechanism parameter, R,, is constant at each lipid composition.…”

Section: Discussionmentioning

confidence: 80%

“…Because these perturbations do not occur with l 8 0 exchange, the existence of the critical composition ( Figure 1) cannot be ascribed to product generation or to hydrolysis-dependent kinetic lags observed with substrate-containing interfaces in the presence of catalytic levels of (phospho)lipases (Verger & Pieroni, 1986). Also, it is independent of the concentration of enzyme in the aqueous subphase ( Figure 1 and Table I), and, at the initial surface pressures and enzyme concentrations used in most experiments, the enzyme does not significantly perturb the interface (Muderhwa & Brockman, 1990). Thus, the critical composition appears to reflect interaction between the enzyme and preexisting lipid organization.…”

Section: Discussionmentioning

confidence: 86%

“…It was also indicated from comparison of CEL adsorption to ester substrate/POPC and DA/POPC monolayers (Muderhwa & Brockman, 1990). In previous studies of ester substrate hydrolysis, the critical composition was observed in a compositional and thermal range over which the components were completely miscible and their acyl chains were melted, i.e., monolayers were liquid expanded and bilayers were liquid crystalline.…”

Section: Discussionmentioning

confidence: 98%

“…For example, pancreatic carboxylester lipase (CEL)' activity toward a variety of ester substrates is inhibited in monomolecular films rich in 1 -palmitoyl-2-oleoylphosphatidylcholine (POPC) (Tsujita et al, 1989). POPC reduces enzyme adsorption to these films, but the size of this effect is insufficient to explain the limited extent of substrate hydrolysis (Tsujita et al, 1987;Muderhwa & Brockman, 1990). CEL adsorption to all substrate-containing phosphatidylcholine films was similar on a lipid area adjusted basis but was distinct from adsorption to films of POPC and 13,16-cis,cis-docosadienoic acid (DA).…”

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confidence: 98%

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Regulation of fatty acid oxygen-18 exchange catalyzed by pancreatic carboxylester lipase. 2. Effects of lateral lipid distribution in mixtures with phosphatidylcholine

Muderhwa

Brockman²

1992

Biochemistry

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The lipase-catalyzed exchange of the carboxyl oxygens of 13,16-cis,cis-docosadienoic acid (DA) was studied in the presence of a nonsubstrate matrix lipid, 1-palmitoyl-2-oleoylphosphatidylcholine. For mixed lipid films at the argon-water interface exposed to pancreatic carboxylester lipase (EC 1.1.1.13), the extent of oxygen exchange showed an abrupt increase as the abundance of DA in the interface was increased from 0.5 to 0.6 mole fraction. This compositional range was independent of the level of enzyme used and of the surface pressure, i.e., lipid packing density, of the film. Concomitant with the transition was a change in the apparent mechanism of exchange from coupled to random sequential. Like the extent of oxygen exchanged, the shift in mechanism was independent of all variables except the lipid composition of the interface. The absence of any chemical or physical change accompanying the exchange reaction precludes mechanistic explanations based on the generation of reaction products by the enzyme. Instead, the results suggest that the lateral distribution of DA in phosphatidylcholine-DA interfaces regulates the expression of carboxylester lipase activity and its apparent mechanism. Preliminary measurements give an average cluster size of 1825 molecules of DA when its mole fraction is 0.35. As the DA content of the interface reaches 0.5-0.6, there appears to be a lipid head-group based percolative transition in which DA becomes the continuum. Because this transition involves the lateral organization of the lipids themselves, other interfacially active enzymes may be regulated similarly.

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Section: Discussionmentioning

confidence: 80%

Section: Discussionmentioning

confidence: 86%

Section: Discussionmentioning

confidence: 98%

mentioning

confidence: 98%

See 2 more Smart Citations

Regulation of fatty acid oxygen-18 exchange catalyzed by pancreatic carboxylester lipase. 2. Effects of lateral lipid distribution in mixtures with phosphatidylcholine

Muderhwa

Brockman²

1992

Biochemistry

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“…This point remains unclear, partly because the mechanism of HDL-vesicle interaction is controversial with respect to at least one point : the participation of HDL as a whole, or only of the apoproteins A1 and/or A11 [23,24]. However, as far as the apoprotein A1 is concerned, its interaction with phospholipids depends on lateral pressure [25], which is related to the PtdSer content as well as to the cholesterol content [26].…”

Section: Interaction Of H D L With Negatively Charged Vesicles Is Regmentioning

confidence: 99%

The influence of the internal content of negatively charged liposomes on their interaction with high‐density lipoprotein

Vidal

Bienvenüe

Sainte‐Marie

et al. 1984

European Journal of Biochemistry

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The release of the internal content of negatively charged phosphatidylcholine/phosphatidylserine vesicles under the influence of high density lipoprotein was studied. Under standard conditions (the same composition outside and inside the compartment) the leakage of negative liposomes increased significantly. However, a high internal concentration of calcein provoked a sealing effect, exhibited both in sucrose and in calcein release. This sealing effect is not related to the size of vesicles, the fluidity of the membrane, the distribution of phosphatidylserine molecules, or the membrane potential. Our data indicate that surface potential influences this effect, probably in addition to a lateral pressure effect such as with cholesterol. The surface potential, as measured by the water-lipid partition coefficient of fatty acids, is strongly affected by internal ionic strength when liposomes contain calcein as well as other polyanions (6-carboxyfluorescein, sodium citrate).The liposome-mediated transfer of drugs to cells is currently the object of many investigations (see [l] for a review). Numerous factors are crucial to the transfer: the encapsulation ratio, the stability of vesicles in serum, the overall clearance rate, the specificity of the interaction and the internalization yield of vesicles. The influence of many of these different factors has been analyzed, viz. size, charges, or composition of vesicles. Several generally accepted rules appear to be applied by most authors. For instance, negatively charged vesicles in a liquid crystal state are often used. Cholesterol is generally added in order to restrain the HDL-provoked leakage of the internal content of the liposomes. With this procedure, a weak internalization yield is obtained, even in uitro where poly(ethy1ene glycol) can be added to increase the fusion process [2].The role of HDL particles in the disruption of PtdCho vesicles is now well documented [3], but almost nothing is known about HDL-negatively charged vesicles interactions. In order to assess the use of this kind of liposome in uivo, we investigated its interaction with serum lipoproteins. This paper is devoted to the influence of the internal content of negative vesicles on their interaction with HDL particles. We show that high internal ionic strength decreases the vesicles surface potential. This leads to a very strong attenuation of HDLvesicle interaction, corresponding to a sealing effect analogous to the one observed with cholesterol.

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Monolayers of 1,2,3-propanetriol esters at the air-water interface: two-dimensional phases and miscibility

Niccolai

Baglioni

Dei

et al. 1989

Colloid & Polymer Sci

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Monolayers of two glycerol esters, 1-monooleoylglycerol and 1-monostearoylglycerol, were studied at the air-water interface in the 15-30 ~ temperature range.From the experimental isotherms (surface pressure vs area and surface potential vs area) the surface phases of the esters were inferred.The miscibility between the two esters was discussed in relationship to the interfacial orientations and distributions and to the surface phases of the esters.The results obtained supported and strengthened the empirical rule on miscibility previously found [1-7], i.e., for non-ionic compounds the same interfacial orientation of the hydrophobic chains is required in order to have bidimensional miscibility between the components.

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Mixed Monolayers Containing Phosphatidylcholine, Cholesterol, Oleic Acid, and Mono- and Triolein.

Cited by 12 publications

References 0 publications

Regulation of fatty acid oxygen-18 exchange catalyzed by pancreatic carboxylester lipase. 2. Effects of lateral lipid distribution in mixtures with phosphatidylcholine

Regulation of fatty acid oxygen-18 exchange catalyzed by pancreatic carboxylester lipase. 2. Effects of lateral lipid distribution in mixtures with phosphatidylcholine

The influence of the internal content of negatively charged liposomes on their interaction with high‐density lipoprotein

Monolayers of 1,2,3-propanetriol esters at the air-water interface: two-dimensional phases and miscibility

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