The interaction and orientation of Peptide KL4 in model membranes

We report on the orientation and location of synthetic pulmonary surfactant peptide KL4, (KLLLL)4K, in model lipid membranes. The partitioning depths of selectively deuterated leucine residues within KL4 were determined in DPPC:POPG (4:1) and POPC:POPG (4:1) bilayers by oriented neutron diffraction. These measurements were combined with an NMR-generated model of the peptide structure to determine the orientation and partitioning of the peptide at the lipid–water interface. The results demonstrate KL4 adopting an orientation that interacts with a single membrane leaflet. These observations are consistent with past 2H NMR and EPR studies (Antharam et al., 2009; Turner et al., 2014)

Investigating the Effect of Medium Chain Triglycerides on the Elasticity of Pulmonary Surfactant

In recent years, vaping has increased in both popularity and ease of access. This has led to an outbreak of a relatively new condition known as e-cigarette/vaping-associated lung injury (EVALI). This injury can be caused by physical interactions between the pulmonary surfactant (PS) in the lungs and toxins typically found in vaping solutions, such as medium chain triglycerides (MCT). MCT has been largely used as a carrier agent within many cannabis products commercially available on the market. Pulmonary surfactant ensures proper respiration by maintaining low surface tensions and interface stability throughout each respiratory cycle. Therefore, any impediments to this system that negatively affect the efficacy of this function will have a strong hindrance on the individual’s quality of life. Herein, neutron spin echo (NSE) and Langmuir trough rheology were used to probe the effects of MCT on the mechanical properties of pulmonary surfactant. Alongside a porcine surfactant extract, two lipid-only mimics of progressing complexity were used to study MCT effects in a range of systems that are representative of endogenous surfactant. MCT was shown to have a greater biophysical effect on bilayer systems compared to monolayers, which may align with biological data to propose a mechanism of surfactant inhibition by MCT oil

Simulated Breathing: Application of Molecular Dynamics Simulations to Pulmonary Lung Surfactant

In this review, we delve into the topic of the pulmonary surfactant (PS) system, which is present in the respiratory system. The total composition of the PS has been presented and explored, from the types of cells involved in its synthesis and secretion, down to the specific building blocks used, such as the various lipid and protein components. The lipid and protein composition varies across species and between individuals, but ultimately produces a PS monolayer with the same role. As such, the composition has been investigated for the ways in which it imposes function and confers peculiar biophysical characteristics to the system as a whole. Moreover, a couple of theories/models that are associated with the functions of PS have been addressed. Finally, molecular dynamic (MD) simulations of pulmonary surfactant have been emphasized to not only showcase various group’s findings, but also to demonstrate the validity and importance that MD simulations can have in future research exploring the PS monolayer system

Catechin and other catechol-containing secondary metabolites: Bacterial biotransformation and regulation of carbohydrate metabolism

Background: Catechol, 1,2-dihydroxybenzene, prepared through bacterial biotransformation from higher order polyphenols, has been proposed to regulate carbohydrate metabolism, especially in the context of type 2 diabetes. This review aims to contextualize this finding. It describes the bacterial biosynthesis of catechol both from glucose, and as a degradation product of higher order natural products through bacterial transformation. The review then considers the mechanism of action of glycemic-regulating catechol-containing materials and the complications arising from balancing their inherent activity with that of catechol, their common degradation product. It then enumerates potential dietary sources of catechin from common foods. Methods: Articles were found through using a combination of key word searches in Pubmed, Web of Science, and Scifinder, coupled with following relevant references in those articles, and tracking the articles that cite them. This is not a systematic review, so only those references germane to the specific needs of the review were included. Results/conclusion: Catechol is a potentially promising metabolite for modulating metabolism, but the sources of the catechol themselves mediate glucose homeostasis through a number of competing mechanisms. The levels of catechins is quite low in most dietary foods with the exception of cocoa, chicory, and green tea. Catechin-rich green tea might prove a useful dietary supplement to work with a catechol-producing probiotic; however, further studies are required to determine the physiological relevance of this approach