Unimolecular films of polymyxins A, B, D and E at the air-water interface

Few, A. V.; Schulman, J. H.

doi:10.1042/bj0540171

Cited by 19 publications

(4 citation statements)

References 10 publications

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“…Polymyxin B was found to have a molecular area of 1.23 k0.05 nm2, at any surface pressure. As this value was very similar to the limiting molecular area of 1.23 nm2 found for polymyxin B alone spread as a monolayer, just before film collapse [20], it was concluded that a total penetration of the polypeptide within the host lipid molecules had occurred [4].…”

Section: Discussionsupporting

confidence: 69%

A study of the structure and dynamics of complexes between polymyxin B and phosphatidylglycerol in monolayers by fluorescence

Théretz

Teissié

Tocanne

1984

European Journal of Biochemistry

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Interactions between the antibiotic polymyxin B and monolayers of dipalmitoylglycerophosphoglycerol have been reinvestigated through a study of the structure and dynamics of the complexes by means of an interface fluorimeter of our fabrication. A fluorescence technique has been developed where the use of linearly polarized incident beams gives the simultaneous determination of the orientation and the lateral diffusion rate of a fluorescent probe inserted in the film. The present investigation was carried out with 12-(9-anthroyloxy)-stearic acid, a fluorescent compound which forms non-fluorescent photodimers upon illumination. Orientation of the probe was studied by computing the ratio of the two dimerization constants K,, and the ratio of the fluorescence intensities obtained with crossed linearly polarized incident lights. The lateral diffusion rate of the probe was obtained by measuring fluorescence recovery after photobleaching (photodimerization) of the probe. Control experiments, carried out with dimyristoylglycerophosphocholine, a lipid which does not interact with polymyxin B, show that the antibiotic does not significantly modify the behaviour of the probe. Both in terms of orientation and dynamics, with respect to dipalmitoylglycerophosphoglycerol, when the antibiotic is present in the subphase (1 pM, saturating conditions), data indicate that the lipid remains in a liquid-expanded state. This is true even at a high surface pressure ( T C Z 37 mN 'm-'), above the apparent 'transition' which can be observed at 30-35 mN .m-' on its compression isotherm. Computation of the contribution of polymyxin B to the film expansion leads to the conclusion that this 'transition' would be a structural transition between two models of interaction: one, below the 'transition', where the polypeptide ring penetrates between the film-forming lipid molecules and another one, above the 'transition', were the antibiotic is adsorbed at the lipid-water interface with only its hydrocarbon chain penetrating the film.Polymyxins are antibiotics isolated from various strains of Bacillus polymyxa, the activity of which is directed mainly against gram-negative bacteria [I]. Polymyxins consist of one fatty acid residue attached through an amide bond to a linear tripeptide linked to a heptapeptide ring. The presence of five or six 2,4-diaminobutyric acid residues confers a net positive charge to these molecules. It is now well recognized that the primary site of action of these antibiotics is the bacterial membrane [I]. As shown by studies carried out with lipids in membrane models, polymyxin B displays a marked preference for acidicphospholipids [I -71. Its interactions are directed by both electrostatic and hydrophobic forces [I].In the case of phosphatidylglycerol, monolayer studies have shown that, at saturation, these interactions achieve a phosphatidylglycerol-polymyxin B complex in the molar ratio 5:l [4]. No interaction was detected with the zwitterionic phosphatidylcholine [2 -41. In bilayer systems and in nonsaturating conditi...

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Section: Discussionsupporting

confidence: 69%

A study of the structure and dynamics of complexes between polymyxin B and phosphatidylglycerol in monolayers by fluorescence

Théretz

Teissié

Tocanne

1984

European Journal of Biochemistry

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“…As it is becoming increasingly clear that the proteins are built up of fundamental subunits of polypeptide chains of molecular pressure studies are likely to yield much of protein structure, although owing to the complexity of the cohesion effects, numerical values of molecular weights may be in error. For example, since these experiments were completed the apparatus has been found useful in determining the molecular weight range of a series of polymyxins 20 For studies in the low surface-pressure field it would seem that the present apparatus has several advantages over those developed by other workers. It is fairly robust but more sensitive than the apparatus used by Bull; it has a wider range of application than the apparatus of Guastalla and it is simpler and quicker in operation than either.…”

Section: Discussionmentioning

confidence: 90%

A study of monolayers at low surface pressures

Allan¹,

Alexander²

1954

Trans. Faraday Soc.

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A sensitive surface balance has been developed for the measurement of low surface pressures. It has been found that the surface pressure against area relationships of the gaseous films are affected by molecular cohesion at the air/aqueous interface so that molecular weights cannot be estimated reliably from the equation l7A = 17Ao + nRT.On the other hand, it is suggested that low surface pressure studies make it easy to distinguish between proteins and their dissociation products.

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“…Few and Schulman (49), using purified samples of sodium penicillin G, observed very little surface activity except at pH values below 4.1. Hauser and Marlowe (47) reported that aqueous solutions of sodium and potassium penicillin G were highly surface active, but Kumler and Alpen (48) reported only slight decreases in surface tension of water in the presence of these salts.…”

Section: Antibiotics and Antibacterial Agentsmentioning

confidence: 97%

Relationships between Surface Activity and Biological Activity of Drugs

Felmeister

1972

Journal of Pharmaceutical Sciences

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Unimolecular films of polymyxins A, B, D and E at the air-water interface

Cited by 19 publications

References 10 publications

A study of the structure and dynamics of complexes between polymyxin B and phosphatidylglycerol in monolayers by fluorescence

A study of the structure and dynamics of complexes between polymyxin B and phosphatidylglycerol in monolayers by fluorescence

A study of monolayers at low surface pressures

Relationships between Surface Activity and Biological Activity of Drugs

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