Autoxidation of cholesterol monomolecular films

Kamel, A. M.; Weiner, Norman; Felmeister, Alvin

doi:10.1016/0021-9797(71)90200-1

Cited by 36 publications

(10 citation statements)

References 11 publications

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“…The reason for this difference is not clear. The behavior could be caused by an unknown surface-active impurity in their DPPC or cholesterol, by partial oxidation of their cholesterol (Kamel et al, 1971), or if their cholesterol mole fraction in the mixed monolayers were less than was stated. Interestingly, our DPPC/cholesterol π-A isotherms agree quite well with earlier results [e.g., Müller-Landau and Cadenhead (1979) and Albrecht et al (1981)].…”

Section: Discussion Cholesterol's "Condensing Effect" On Sms Versus Pcsmentioning

confidence: 99%

Cholesterol's Interfacial Interactions with Sphingomyelins and-Phosphatidylcholines: Hydrocarbon Chain Structure Determines the Magnitude of Condensation

1994

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Cholesterol's interfacial interaction with different sphingomyelins and phosphatidylcholines has been investigated using a Langmuir film balance. The average molecular area of cholesterol/sphingomyelin (SM) or cholesterol/phosphatidylcholine (PC) mixed monolayers was determined as a function of film composition from the force-area isotherms measured at 24 degrees C. In contrast to previous results [Lund-Katz, S., Laboda, H. M., McLean, L. R., & Phillips, M. C. (1988) Biochemistry 27, 3416-3423], little difference was observed in equimolar cholesterol's "condensing effect" of SMs compared to PCs when their phase state was similar and when their hydrocarbon structural differences were minimized. For PCs, this meant that one acyl chain had to be long and capable of assuming an extended conformation and thus configurationally similar to the long-chain base of SM. This condition facilitated strong van der Waals attractive interactions with cholesterol's planar steroid ring and was satisfied when the sn-1 acyl chain of PC was either myristate or palmitate. Under these conditions, the structural requirements of the sn-2 chain of PC were mitigated. For instance, at equimolar cholesterol, almost no difference was observed in the apparent molecular area condensations of 1-palmitoyl-2-oleoyl-PC and 1-palmitoyl-2-arachidonoyl-PC at surface pressures between 10 and 40 mN/m. In contrast, the apparent molecular area condensations of dioleoyl-PC and diarachidonoyl-PC were substantially reduced under identical experimental conditions. The results are discussed in terms of the relative importance of phospholipid/sphingolipid hydrocarbon and headgroup structure in determining the extent of interaction with cholesterol.(ABSTRACT TRUNCATED AT 250 WORDS)

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Section: Discussion Cholesterol's "Condensing Effect" On Sms Versus Pcsmentioning

confidence: 99%

Cholesterol's Interfacial Interactions with Sphingomyelins and-Phosphatidylcholines: Hydrocarbon Chain Structure Determines the Magnitude of Condensation

1994

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“…Cholesta-4,6-dien-3-one has little effect on the osmotic fragility of erythrocytes but it does markedly alter the permeability of the cells or of liposomes to solutes like glycerol or glucose and packs with phosphatidylcholine in monolayers differently from cholesterol (Bruckdorfer et al, 1969;Demel et al, 1972a,b). However, the work of Kamel et al (1971) indicates that 3-hydroxycholest-5-en-7-one has physical properties very similar to those of cholesterol in monolayers and bilayers of lipid'. It is noteworthy that this compound, probably the most discriminating of the probes used, is incorporated best into liposomes and erythrocytes and causes least haemolysis.…”

Section: Discussionmentioning

confidence: 99%

Optical-rotatory-dispersion studies of compounds related to cholesterol in liposomes and the membranes of erythrocyte ‘ghosts’

Green

Edwards

Green

1973

Biochemical Journal

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1. Steroid molecules containing the alpha,beta-unsaturated oxo group in various positions were incorporated with egg phosphatidylcholine into liposomes and into human erythrocyte membranes. 2. The liposomes formed contained 0.3-0.94mol of steroid/mol of phospholipid and the steroids replaced 19-76% of the erythrocyte membrane sterol. 3. The optical rotatory dispersion (o.r.d.) spectra of the steroids in these structures were compared with those obtained in solvents of different polarity. 4. The o.r.d. spectra of cholesta-4,6-dien-3-one and 3-hydroxycholest-3-en-2-one in liposomes resembled those obtained with polar solvents such as ethanol or triethyl phosphate-water (1:1, v/v). 5. The o.r.d. spectra of 3-hydroxycholest-7-en-6-one and 3-hydroxycholest-5-en-7-one in liposomes resembled those obtained with moderately polar solvents such as dioxan. 6. The o.r.d. spectrum of 3-hydroxycholest-8(14)-en-15-one in liposomes resembled those obtained with non-polar solvents such as cyclohexane. 7. 3-Hydroxycholest-3-en-2-one did not exchange with erythrocyte membrane cholesterol, but the other steroids did do so and the o.r.d. spectra of the membranes containing them closely resembled those obtained with liposomes. 8. From the results, the position of sterol molecules with respect to the phospholipid molecules in liposomes and membranes of human erythrocyte ;ghosts' can be deduced.

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“…-For the measurement of 7T-A isotherms it was crucial that the surfactants and substrate be as pure as possible ; impurities produced substantial distortions in the isotherms. In particular, it proved difficult to obtain cholesterol free of its oxidation product(s) [23], and difficult to prevent it from oxidizing at the air-water interface [18]. Cholesterol was purchased from both Sigma (Sigma Grade 99 +%, as well as cell-culturetested grade 99 +% ; Sigma Chem.…”

Section: Single-mentioning

confidence: 99%

“…The subphase pH drifted to a value of approximately 5.5 within 2 hrs. Measurements were also made on a subphase containing 100 mM 1-ascorbic acid (Fisher Scientific, reagent grade), added to minimize cholesterol oxidation at the air-water interface [23]. Here, the typical subphase pH was found to be 3.5.…”

Section: Single-mentioning

confidence: 99%

Critical mixing in monomolecular films : pressure-composition phase diagram of a two-dimensional binary mixture

Hirshfeld

Seul

1990

J. Phys. France

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Reçu le 17 novembre 1989, révisé le 7 février 1990, accepté le 2 avril) Résumé.-Nous avons mesuré les isothermes pression-surface de monocouches mixtes composées de dimyristoyl lécithine et de cholestérol à 23,5 °C, et nous les avons analysées afin d'établir le diagramme de phase pression-composition de ces mélanges bidimensionnels. Ces mesures sont confirmées par l'observation directe de la séparation de phase. Nous identifions un intervalle de non-miscibilité des états fluides qui se termine par un point critique, accessible à la température ambiante. Nous proposons que, dans les phases mixtes coexistantes, la lécithine se trouve dans des états distincts.

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Autoxidation of cholesterol monomolecular films

Cited by 36 publications

References 11 publications

Cholesterol's Interfacial Interactions with Sphingomyelins and-Phosphatidylcholines: Hydrocarbon Chain Structure Determines the Magnitude of Condensation

Cholesterol's Interfacial Interactions with Sphingomyelins and-Phosphatidylcholines: Hydrocarbon Chain Structure Determines the Magnitude of Condensation

Optical-rotatory-dispersion studies of compounds related to cholesterol in liposomes and the membranes of erythrocyte ‘ghosts’

Critical mixing in monomolecular films : pressure-composition phase diagram of a two-dimensional binary mixture

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