The Structure of Lipid A

Lipid A is believed to be a hydrophobic lipid moiety of the LPS molecule. Lipid A is essentially a phosphorylated glucosamine disaccharide with many fatty acids attached. This part of LPS is responsible for its endotoxin activity (Rietschel et al., 1982). Lipid A is an agent capable of inducing various endotoxin responses such as fever, Schwarzmann reaction, immune cell activation, lethal toxicity etc. (Galanos et al., 1985; Rietchel et al., 1987). Lipid A is embedded in the lipid bilayer of the outer membrane and is necessary for a functional membrane barrier function (Wyckoff et al., 1998).

The macrolipid tissue in the membrane is partly dependent on the monomeric structure of its lipid (Figure 7). Cylindrical lipids such as SM and PC form a layered structure with zero overall curvature. Other lipids such as PE, CHOL or diacylglycerol form films with negative curvature distortion due to their frusto-conical shape. These molecules induce the formation of a reverse hexagonal phase in vitro. Finally, molecules with hydrophilic regions occupying a larger area than the hydrophobic part (such as detergents and lysophospholipids) have inverted cone shapes, which induce a positive curvature in the lipid structure.

Lipids are the most diverse biochemical group. Their major structural applications are as part of the internal and external biofilm, such as cell membranes, or as an energy source. Lipids are often defined as hydrophobic or amphipathic biomolecules, but are dissolved in organic solvents such as benzene or chloroform. Fat is a large class of compounds containing fatty acids and glycerol; glycerol molecules attached to three fatty acid esters are known as triacylglycerides. There are several variations in this basic structure, including alternating frameworks such as sphingosine in sphingolipids and hydrophilic groups in phospholipids such as phosphate. Steroids such as cholesterol are another major class of lipids

Lipids are very diverse in function and structure. Despite this diversity, lipids can be classified into major groups. These three groups are oils, phospholipids, steroids and waxes. Fats and oils are composed of two molecules, and glycerin and three fatty acids are bound by a condensation reaction (loss of water molecules). The components in the structure call these molecules triglycerides, tri-fatty acids and glycerol molecules. Because fat is a solid at room temperature it is called fat, so-called oil is liquid at room temperature. Fats and oils are important to the body to provide a protective layer around the organs and provide insulation