Compositional, structural and functional properties of discrete coexisting complexes within bronchoalveolar pulmonary surfactant



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Castillo Sánchez, José Carlos and Cerrada, Alejandro and Conde, Mikel and Cruz Rodríguez, Antonio and Pérez Gil, Jesús (2022) Compositional, structural and functional properties of discrete coexisting complexes within bronchoalveolar pulmonary surfactant. Biochimica et Biophysica Acta - Biomembranes, 1864 (1). p. 183808. ISSN 0005-2736

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Lung surfactant (LS) stabilizes the respiratory surface by forming a film at the alveolar air-liquid interface that reduces surface tension and minimizes the work of breathing. Typically, this surface-active agent has been isolated from animal lungs both for research and biomedical applications. However, these materials are constituted by complex membranous architectures including surface-active and inactive lipid/protein assemblies. In this work, we describe the composition, structure and surface activity of discrete membranous entities that are part of a LS preparation isolated from bronchoalveolar lavages of porcine lungs. Seven different fractions could be resolved from whole surfactant subjected to sucrose density gradient centrifugation. Detailed compositional characterization revealed differences in protein and cholesterol content but no distinct saturated:unsaturated phosphatidylcholine ratios. Moreover, no significant differences were detected regarding apparent hydration at the headgroup region of membranes, as reported by the probe Laurdan, and lipid chain mobility analysed by electron spin resonance (ESR) in spite of the variety of membranous assemblies observed by transmission electron microscopy. In addition, six of the seven separated LS subfractions formed similar, essentially disordered-like, interfacial films and performed efficient surface activity, under physiologically relevant conditions. Altogether, our work show that a LS isolated from porcine lungs is comprised by a heterogenous population of membranous assemblies lacking freshly secreted unused LS complexes sustaining highly dehydrated and ordered membranous assemblies as previously reported. We propose that surfactant subfractions may illustrate intermediates in sequential structural steps within the structural transformations occurring along the respiratory compression-expansion cycles.

Item Type:Article
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CRUE-CSIC (Acuerdos Transformativos 2021)

Uncontrolled Keywords:Lung surfactantAir, liquid interface, Respiratory dynamics, Membrane structure, DSC, ESR
Subjects:Sciences > Chemistry
Sciences > Chemistry > Molecular biology
Sciences > Chemistry > Biochemistry
ID Code:70126
Deposited On:08 Feb 2022 11:42
Last Modified:18 Oct 2022 08:52

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