  This review describes the analytical calculation of lateral pressure profile
in lipid membrane with finite curvature. The derivation is based on the
previously developed microscopic model of flexible strings [1,2]. According to
this theory the energy per unit chain is considered as energy of flexible
string (Euler's elastic beam of finite thickness) and interaction between
chains is considered as an entropic repulsion. This microscopic theory allows
to obtain expression for lateral pressure distribution in bent lipid membrane
if treating a bending as a small deviation from the flat membrane conformation
and using perturbation theory with small parameter L0J, where L0 is the
monolayer thickness, J is mean curvature of membrane. Because lateral pressure
distribution is related to the elastic properties of lipid bilayer [3] then
first spontaneous moment of lateral pressure and the expression for bending
modulus may be derived from this theoretical model. Finally, based on
analytical expression for the lateral pressure distribution in bent lipid
membrane one can obtain analytically the energy difference between two states
of mechanosensitive channel, particularly MscL [4, 5, 6]. Calculated expression
depends on inter-facial surface tension, the channel area change in region
between hydrophobic interior and the aqueous surroundings and the bending
modulus and spontaneous bending moment values.
