Biomembranes play many structural and functional roles in both prokaryotic
and eukaryotic cells [10]. They define compartments, the communication between
the inside and outside of the cell. The main components of biomembranes are
lipids and proteins, which form protein-lipid bilayer systems [10]. A structure and
physicochemical properties of protein-lipid membranes, which determines biological
activities of biomembranes, are strongly dependent on interactions between
lipid and protein components and external agents such as a temperature, pH, and
a membrane hydration [4]. A lipid bilayer matrix serves as a perfect environment
for membrane proteins (Fig. 1), and it assures activities of these proteins. Because
biomembranes are composed of many different groups of lipids and proteins and
have a complex structure, it is difficult to study in details their physicochemical
properties using physicochemical methods. For these reason, lipid membranes of
liposomes are used in many scientific laboratories for studding processes associated
with a lipid phase transition, a membrane hydration, or protein-membrane interactions.
The structure of liposomes (Fig. 5), and an influence of pH and an ionic
strength on a lipid bilayer structure are discussed in the presented work. The role
of membrane proteins in determination of biological activities of biomembranes is
highlighted. A high variety of a structure and an enzymatic activity of membrane
proteins is responsible for a high diversity of biological functions of cell membranes
[2]. α-Lactalbumin (α-LA) is a peripheral membrane protein (Figs 8 and 9), its
biological function is strongly related to its conformational structure and interaction
with lipid membranes [49]. The complex of α-LA in a molten globule conformational
state with oleic acid, termed as a HAMLET complex, are disused in a context of
its anti-tumor activity