Ovalbumin in developing chicken eggs migrates from egg white to embryonic organs while changing its conformation and thermal stability

Ovalbumin was detected in developing chicken eggs. The large majority of th ese ovalbumin molecules was found to be in a heat-stable form reminiscent o f S-ovalbumin, About 83 and 90% of the ovalbumin population was in a heat-s table form in day 14 or stage 40 amniotic fluid and day 18 or stage 44 egg yolk, respectively, whereas ovalbumin in newly deposited eggs was in the he at-unstable, native form. Purified preparations of stable ovalbumin from eg g white and amniotic fluid showed a les's ordered configuration than native ovalbumin, as analyzed by circular dichroism and differential scanning cal orimetry. In addition, mass spectrometric analysis exhibited distinct size microheterogeneity between the stable and native forms of ovalbumin, Immuno hisotochemical study revealed that ovalbumin was present in the central ner vous system and other embryonic organs. These results indicated that egg wh ite ovalbumin migrates into the developing embryo while changing its higher order structure.