ヨウ素強化卵卵黄画分中のヨウ素の分布

In order to clarify the iodine distribution in iodine-enriched eggs, Na¹²⁵I (0.7mCi) was orally administered to egg-laying hens and ¹²⁵I uptake was examined. Radioactivity (¹²⁵I) was found predominantly in the egg yolk rather than in the egg white (approximately 30 times more radioactivity per gram).<br>The components of the egg yolk were fractionated by various methods, and the ratios of ¹²⁵I radioactivity in each fraction to the total radioactivity were calculated. Iodine distribution was about 18% in the protein fraction, about 8% in the lipid fraction and about 74% in the water-soluble fraction as determined by extraction with Folch's solvent, and its distribution was about 15% in the protein fraction, about 24% in the lipid fraction and about 61% in the water-soluble fraction as determined by extraction with butanol. The egg yolk was suspended with 1% sodium chloride, and lipoproteins in the egg yolk were fractionated into 7 fractions by ultracentrifugation. The iodine distribution was less than 1% in the precipitable fractions [lipovitellin fraction (fr 1), phosvitin fraction (fr 3) and γ-livetin fraction (fr 7)] and 5-55% in the supernatant fractions (frs 2, 4 and 6). When each fraction separated by ultracentrifugation was further fractionated with Folch's solvent, 80-90% of iodine was found in the aqueous fraction of all lipoprotein fractions except for lipovitellin fraction.<br>Thus, iodine in the iodine-enriched egg yolk was distributed widely in protein, lipid and aqueous fractions, but was mostly present in the aqueous fraction as a low-molecular-weight substance which was not precipitated by ultracentrifugation.