Isolation and characterization of riboflavin-binding protein from pregnant-rat serum.

A high-affinity riboflavin -binding protein was isolated and characterized for the first time from pregnant-rat sera by affinity chromatography on a lumiflavin-agarose column. The purified protein was homogeneous by the criteria of analytical polyacrylamide-gel disc electrophoresis, gel-filtration chromatography on Sephadex G-100 and sodium dodecyl sulphate/polyacrylamide-gel electrophoresis. It had a molecular weight of 90000+/-5000 and interacted with [14C]riboflavin with a 1:1 molar ratio with a dissociation constant (Kd) of 0.42 micron.