MODELING OF ENTAMOEBA-HISTOLYTICA FERREDOXIN

The E. histolytica ferredoxin (EHFXD) is an iron-sulphur protein and i s important in the control of E. histolytica because it donates an ele ctron to and activates metronidazole (4) the most effective anti-amoeb ic drug. The knowledge of the three-dimensional structure of EHFXD can help to assist in rational design of anti-amebic drugs. Homology mode ling of EHFXD has been done by using the knowledge of crystal structur e of homologous Ferredoxin structures. It has been shown that EHFXD is more likely to;contain 2[4Fe-4S] clusters and has a pseudodiad symmet rical fold. The fold is stabilised by hydrophobic patches as well as b y intramolecular hydrogen bonds. The importance of two Leu residues in the N- and C-termi in bridging the two clusters has been emphasised. The electrostatic properties of the surface of EHFXD were examined and compared with that of other ferredoxins. It was observed that large r egions of negative as well as positive electrostatic potential is a co mmon feature of the [4Fe-4S] containing ferredoxins which might explai n their biological role as both electron acceptor and electron donor m olecules.