posted on 2024-03-01, 19:07authored byAnand
Kumar Sahu, U. Chandrasekhar Reddy, Muraleedharan Kannoth Manheri, Ashok Kumar Mishra
The
present study focuses on exploring the physical properties
of lipid membranes based on the polyhydroxy oxanorbornane (PH-ONB)
headgroup, designed as synthetic analogues of naturally occurring
archaeal lipid membranes. Specifically, we study two variants of PH-ONB
headgroup-based lipids differing in the number of hydroxy groups present
in the headgroup, with one having two hydroxy groups (ONB-2OH) and
the other having three (ONB-3OH). These lipids form stable bilayer
membranes. The study begins with a comprehensive analysis of the fluorescence
characteristics of nitrobenzoxadiazole (NBD)-tagged ONB-based lipids
in different solvent environments and within a model lipid membrane
1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC).
Subsequently, the physical properties of the ONB-based membranes were
examined by using an NBD-tagged ONB-based probe and a commonly used
extrinsic 1,6-diphenyl-1,3,5-hexatriene (DPH) fluorescent probe. The
steady-state and time-resolved fluorescence properties of the NBD-tagged
ONB-based probe and DPH were used to compare the physical properties
of the ONB-based membranes, including polarity, fluidity, phase transition,
order, hydration, location, heterogeneity, and rotational diffusion.
The solid gel to liquid crystalline phase transition temperatures
of ONB-2OH and ONB-3OH lipid membranes are found to be (68 ±
1) °C and (74 ± 1) °C, respectively. The variation
in organization (size), fluidity, and phase transition temperature
of ONB-based lipid membranes is explained by the extent of hydrogen
bonding interactions between lipid head groups. ONB-based membranes
exhibit characteristics similar to those of phospholipid membranes
and possess a notably high phase transition temperature. These properties
make them a promising and cost-effective synthetic alternative to
archaeal lipid membranes with a wide range of potential applications.