WATER OF HYDRATION AND CONFINED WATER ARE RELEVANT FOR THE STRUCTURAL AND FUNCTIONAL PROPERTIES OF BIOMEMBRANES.

DISALVO, E; LAIRION, F; MARTINI, F; FRÍAS, M. A; DÍAZ, S; TYMCZYSZYN, E

Baltimore, USA

Congreso; Annual Meeting Biophysical Soc; 2007

Biophysical Soc

The classical picture of a cell is an aqueous compartment in which the membrane is the barrier of contention of the cellular material. Although, water is essential to preserve the membrane structure, cell growing depends on a small fraction of cytoplasmic volume and the enzymatic activity requires only one monolayer of water. Crowded macromolecules in a cell’s cytoplasm would be held at a short distance from the membrane surface. Thus, the structure and properties of water adjacent to membranes  appear essential for the functional activity of the membrane in a living cell. In this context, the membrane described by the fluid mosaic model is no longer valid. Relevance to the interfacial properties of the  membrane should be considered to understand the complex functionality of a cell stability and growing. Considering the membrane interphase as a bidimensional solution of polar heads, infrared spectroscopy and surface studies provide information related to: .-Tightly bound and weakly associated water molecules are influenced by the carbonyl and phosphate groups according to the groups sterified to the phosphate (choline, ethanolamine, glycerol). .-Water confined between the lipids affects the activity of aqueous soluble enzymes depending on the surface pressure and phase state of the surface. .-The variety of lipids found in a cell membrane may modulate the cell volumen recovery and the interaction of protein normally found in aqueous space in relation to its hydration, lateral interactions and lipid head group nature. .- Coexistance of different lipid in different phase states gives place to defects in the hydrogen bonding network at the membrane surface which is crucial for regulation of some enzymatic processes. .