Ordering effects of cholesterol and its analogues

Abstract

Without any exaggeration, cholesterol is one of the most important lipid species in eukaryotic cells. Its effects on cellular membranes and functions range from purely mechanistic to complex metabolic ones, besides which it is also a precursor of the sex hormones (steroids) and several vitamins. In this review, we discuss the biophysical effects of cholesterol on the lipid bilayer, in particular the ordering and condensing effects, concentrating on the molecular level or inter-atomic interactions perspective, starting from two-component systems and proceeding to many-component ones e.g., modeling lipid rafts. Particular attention is paid to the roles of the methyl groups in the cholesterol ring system, and their possible biological function. Although our main research methodology is computer modeling, in this review we make extensive comparisons between experiments and different modeling approaches.

Line tension of the pore edge in phospholipid/cholesterol bilayer from stretch molecular dynamics simulation

“…Although estimation of the bending modulus at the nanometer edge is a challenging problem (Nakamura and Shinoda, 2013), we suspect that the increase of the cholesterol concentration around the pore edge increases the bending modulus of the pore edge and the line tension (Genova et al, 2014). According to previous experimental (Mills and Toombes, 2008) and simulation studies (Róg et al, 2009), cholesterol molecules rectify the disordered orientations of hydrophobic tails of co-existing phospholipid molecules, which is one of the causes for the high bending moduli of cholesterol-containing bilayers. In our MD simulations, the cholesterol molecules are distributed around the pore edge (Fig.…”

Zeta potential and surface charge of DPPC and DOPC liposomes in the presence of PLC enzyme

“…Cholesterol molecules happens to be incorporated into the phospholipid's bilayer thus causing increase separation between the choline head groups, reduces the hydrogen bonding strengths and electrostatic interaction. This makes the membrane more stable and lowers its permeability to water and other molecules (Ohvo-Rekilä et al 2002;Róg et al 2009). A special role plays calcium Ca ?2 cations causing modulation of the insertion of proteins.…”

Be straight to better coordinate two -- Head groups and extended acyl chains of raft-like bilayer lipids can localize in groove between dimerized transmembrane helical peptides and assist sequence-nonspecific stabilization of peptide dimers by cholesterol

“…Lipid chain ordering within the bilayers. The ordering was quantified via the deuterium order parameter, −S CD , which is defined as −S CD = (1/2) S z , where S z = (1/2) «3cos 2 (θ z ) − 1», and θ z stands for the angle between the C-H bond vector and the bilayer normal, and the double angle bracket denotes the ensemble average [16]. S z can vary between 1 (full order along the normal) and -0.5 (full order perpendicular to the normal).…”