Kinetics of Destabilization of Calcitonin Monolayers at the Air/Water Interface

Romeu, Nuria Vila; a̧, Patrycja Dynarowicz-Ł; Trillo, José Miñones; Seoane, J. R.; Mouzo, Olga Conde

doi:10.1006/jcis.1997.5263

Cited by 2 publications

(5 citation statements)

References 25 publications

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“…As expected, the sCT isotherm is located at the highest mean molecular area (MMA) values, characterized by a pronounced knee, at approximately 400 Å 2 and 18 mN/m, in agreement with previous observations [73] , [74] . In a detailed study, Romeu et al demonstrated that this knee and the following zone of an increased compressibility can been attributed to a film instability.…”

Section: Resultssupporting

confidence: 92%

“…Finally, the inset of Fig. 3 a shows the “ΔG-analysis” results of our system and, as discussed by Romeu et al [73] , [74] , can be considered “quantitative” only for pressures less than the sCT knee (5, 15 mN/m). ΔG grows up to a 0.34 sCT molar fraction, reaching a maximum (about 3 KJ/m), suggesting that, up this molar fraction, a protein aggregation occurred in the monolayer.…”

Section: Resultsmentioning

confidence: 80%

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Monosialoganglioside-GM1 triggers binding of the amyloid-protein salmon calcitonin to a Langmuir membrane model mimicking the occurrence of lipid-rafts

Diociaiuti

Giordani

Kamel

et al. 2016

Biochemistry and Biophysics Reports

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GM1 ganglioside is known to be involved in the amyloid-associated diseases and it is a crucial factor for the assembly of amyloid proteins on lipid-rafts, which are lipid structures located on the synaptic plasma membranes. Due to its slow aggregation rate, we employed salmon calcitonin (sCT) as a suitable probe representative of amyloid proteins, to study the interaction between this class of proteins and a membrane model. Here, we prepared a neuronal membrane model by depositing onto mica two Langmuir-Blodgett films in liquid-condensed phase: the outer monolayer was characterized by high content of GM1 (50%) and minority parts of cholesterol and POPC (25–25%), while the inner one by plain POPC. To deeply investigate the interaction of sCT with this model and the role-played by GM1, we prepared the outer leaflet adding sCT at a concentration such that the number of proteins equals that of GM1. Atomic Force Microscopy revealed the occurrence of two distinct kinds of flat surfaces, with globular aggregates localized exclusively on top of the highest one. To unravel the nature of the interaction, we studied by ζ-potential technique liposomes composed as the outer leaflet of the model. Results demonstrated that an electrostatic interaction sCT-GM1 occurred. Finally, to investigate the interaction thermodynamics between sCT and the outer leaflet, Langmuir films as the outer monolayer and containing increasing content of sCT were studied by compression isotherms and Brewster Angle Microscopy experiments. Based on the all body of results we propose an interaction model where GM1 plays a pivotal role.

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Section: Resultssupporting

confidence: 92%

Section: Resultsmentioning

confidence: 80%

Monosialoganglioside-GM1 triggers binding of the amyloid-protein salmon calcitonin to a Langmuir membrane model mimicking the occurrence of lipid-rafts

Diociaiuti

Giordani

Kamel

et al. 2016

Biochemistry and Biophysics Reports

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show abstract

“…However, as t approaches a value of the order of L 2 st /D (~100 s for our data below), convection accelerates the process and leads to positive deviations from eqn (13) long before its limit (15) is reached.…”

Section: Desorption In the Isobaric Regime Under Barrier-diffusion Control: Theorymentioning

confidence: 76%

“…A common application [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] of the Langmuir trough is to follow the process of desorption of a spread monolayer of slightly soluble amphiphile under isobaric conditions, where the decrease of the area A of the film with time t is monitored at constant surface pressure  S ( S = 0 , where 0 and are the surface tensions of the pure solvent and of the monolayer). The isobaric regime has been used for determination of the diffusion coefficient D of the surfactant [5] and for evaluation of its solubility [11]; to study the dissociation and the Hofmeister effect on the properties of monolayers of adsorbed acids [7]; to study the processes involved in the collapse of the monolayer [8,12]; phase transitions [14] in monolayers; interaction between adsorbed lipids and proteins [10]; and generallythe mechanism of desorption [4,6,9].…”

Section: Introductionmentioning

confidence: 99%