الفهرس Only 14 pages are availabe for public view
 |  | from | 199 |  |  |
| | | from | 199 | | |
Abstract
Name: Walaa Hussein Salama Hussein
Title of thesis: Biochemical and immunochemical studies on phospholipase A2 (PLA2 (enzyme from venoms of certain species of elapids and vipers found in Egypt.
Despite of the fact that functionally diverse phospholipase A2 variants of snake venoms are well characterized at the level of protein and gene sequences; the patterns of individual snake venom PLA2s are poorly known. We investigated the specific activities, molecular weights and isoelectric points of the PLA2s of some medically important snake venoms in Egypt, the vipers (Pseudocerastes persicus fieldi, Cerastes cerastes and Echis carinatus) and the Elapids (Naja haje, Walterinnesia aegyptia and Naja nigricollis) venoms were investigated.
Four PLA2 containing fractions named (N. nigricollis CM-PLA2I-IV) and two PLA2 fractions named (N. haje CM-PLA2I, II) were purified from N. nigricollis and N. haje snake venom, respectively, using gel filtration chromatography followed by ion exchange chromatography.
Characterization of the isolated PLA2 isoenzymes revealed similarities in molecular weights and differences in the isoelectric points, the optimum temperature, optimum pH, optimum Ca+2 concentration and metal ion requirements.
A good correlation (r>0.9) between the in vitro neutralization of enzymatic PLA2s activity and the ELISA titers was found for sera collected one week after each boosting dose. These correlations were particularly high with the prepared anti-Seph-PLA2 rabbit antisera rather than the anti-whole venom antisera. As well, a good correlation was demonstrated for the antisera raised in horses for N. haje venom. Furthermore, a good correlation was found between the in vivo neutralization of the venom in mice, the in vitro neutralization of enzymatic PLA2s activity and the ELISA antibodies titers (r>0.85).
These findings have a potential application in evaluation of the antivenom production. As the therapeutic antivenoms are traditionally produced in large animals, the established correlations helps in cutting down the production costs and overcome the ethical arguments concerning the extensive use of experimental animals.
Key Words:
Phospholipase A2, snake venom, isoenzymes, antivenom, purification and characterization, correlation, Cerastes cerastes, Echis carinatus, Pseudocerastes persicus fieldi, Naja haje, Naja nigricollis and Walterinnesia aegyptia.