Exploring proton transport properties along lipid membranes

 

Proton dynamics on the surface of biological membranes are at the heart of bioenergetics which has been the subject of detailed studies ever since the discovery of chemiosmotic theory in mid-1960s. Such studies resulted in the understanding that the proton dynamics on membrane is more complicated than in pure aqueous media. Despite the efforts, the fundamental mechanism of proton diffusion (PD) is still poorly understood due to its complex nature of PD along distinct types of lipids and its interaction with the bulk phase. Thus, we aim to investigate how PD along lipid membranes is influenced by different membrane composition and bulk proton concentrations.

To do so, we developed two experimental approaches. The first one is based on a fluorescent probe that can be tethered to the surface of lipid vesicles and can inject a proton to the surface of the membrane on demand following light excitation. The latter is focused on a molecular protonics approach to investigating lateral PD over long distances (~100 mm) in a solid state like environment. Accordingly, the seminar is divided into two parts. In the first part, I will discuss how lipid composition, membrane phase, distinct phospholipid linkage and sterol content shape proton dynamics of membranes. The second part will highlight the role of lipid head groups, tail regions, and membrane fluidity in facilitating long-range PD along lipid membranes.

 

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