Avian Riboflavinuria

The stability of the avian riboflavin-binding protein complex (1 × 107 M–1) was studied within incubating normal eggs. Immuno-chemical and fluorescence titration analyses demonstrated that synthesis of 0.1 mg. of riboflavin-binding protein per g. of egg content occurred by day-13. From day-13 through day-18 a net loss of the protein was observed. The riboflavin-binding protein-riboflavin complex increased 100% through day-15. FMN was converted to free riboflavin, lumichrome and lumiflavin in incubating recessive eggs. Conversion to free riboflavin accounts for the doubling observed in normal eggs. The absence of degradation products in normal incubating eggs indicated that holoprotein protected B2 from destruction during the early stages of embryonic development.