RESUMO
Isoelectric focussing of amniotic fluid of chick system over pH gradient of 4-6 revealed presence of 8 superoxide dismutases. The superoxide dismutase (SOD) isozymes were identified as one major isozyme and other seven were minor ones. Higher expression of SOD (major isozyme) with exposure of 1000 R was studied. The isoelectric point (pI) of major SOD isozyme in control (5) differs from radiation exposed samples (5.12). Hence in radiation exposed amniotic fluid showed more pronounced SOD major isozyme, than control amniotic fluid. It is clearly evident that the SOD isozyme with X-irradiation having different isoelectric points, may lead to modification of the amino acid composition and charges of amino acids in the protein structure of SOD. So, the higher SOD isozyme expression has a role in defence action against free radical damage by X-irradiation during embryonic development.