Conformation-dependent antigenic structure

Structural and antigenic properties of proteins are expected to change after one-electron redox processes whatever they are. Such effect was demonstrated using ovalbumin and bovine serum albumin (226). Antigenicity was decreased by irradiation. This change could be related to that measured by circulary dichroism at 222 nm. The authors suggest that the main part of conformation-dependent antigenic structure is lost by irradiation. 

Antigen antibody recognition is dependent on protein structure. A conformational change in a protein caused by formalin fixation may mask the epitope and thus affect the antigenicity of proteins in formalin-treated tissue (Montero 2003). The antigen retrieval leads to a renaturation or at least partial restoration of the protein structure, with re-establishment of the three-dimensional protein structure to something approaching its native condition (Shi et al. 1991). 

Figure 2 A cartoon of Pauling s instructive theory for the formation of how antibodies may be formed. An unspecific antibody precursor, represented as an oligomeric entity here, comes in contact with an antigen and engulfs a portion of the antigenic surface. In this contact formation, the antibody precursor would adopt a complementary structure to the antigen. In Pauling s theory, the antibody precursor would then mature to a specific antibody for that particular antigen and would then retain its conformation and specificity even after dissociation. Note it is now known that the conformation and specificity of antibodies is purely dependent on the genetic code. Antibodies originate from specific cell clones and details about the mechanism of the immune system can be found in biochemistry textbooks [9].

Undecaprenol (bactoprenol) from Salmonella contains eleven isoprene units, and two irons and nine cis double bonds In the form of undecaprenyl phosphate, it acts as a carrier of carbohydrate residues in the biosynthesis of bacterial antigenic polysaccharides synthesis of Murein (see) also depends on undecaprenyl phosphate. In eukaryotes the Dolichol phosphates (see) function in the transfer of carbohydrate residues in the synthesis of glycoproteins and glycoli-pids. Probably the long lipid chains of these P serve to anchor them in membranes, while the phosphate group acts as a carrier by protruding into the cytoplasm. It is not known whether all P. function as carbohydrate carriers. The structural relationship between solanesol and plastoquinone-9 and ubiquinone-9, and the joint occurrence of these compounds suggest a precursor role for P. Biosynthesis of P. proceeds from mevalonic acid and the conformation of all double bonds is predetermined in early precursors. 

---