title: Relationship between biotin-binding proteins from chicken plasma and egg yolk.
abstract: The plasma of laying hens contains a specific biotin-binding protein that appears to be identical with an egg-yolk biotin-binding protein. Both proteins are saturated with biotin and require elevated temperatures to effect the exchange of [14C]biotin for the protein-bound vitamin. The heat-exchange curve in each case is the same and differs sharply from that of avidin, the egg-white biotin-binding protein. On Sephadex G-100 gel filtration, plasma and yolk biotin-binding proteins were each eluted slightly ahead of avidin (mol.wt. 68,000), suggesting that they are of similar molecular weight. Plasma and yolk biotin-binding proteins required the same ionic strength to be eluted from a phosphocellulose ion-exchange column. Both the plasma and yolk biotin-binding proteins had a pI of 5; avidin has a pI of 10. Plasma biotin-binding protein cross-reacted with antiserum to yolk biotin-binding protein and showed a precipitin line of identity with purified yolk biotin-binding protein. It is suggested that biotin-binding plays an important role in mediating the transport of the vitamin from the bloodstream to the developing oocyte.
mesh_terms: D000818:Animals; D001710:Biotin / Q000097:blood / Q000378:metabolism*; D002352:Carrier Proteins / Q000097:blood / Q000378:metabolism*; D002645:Chickens; D002850:Chromatography, Gel; D002852:Chromatography, Ion Exchange; D004527:Egg Proteins / Q000378:metabolism; D004530:Egg Yolk / Q000032:analysis*; D005260:Female; D005779:Immunodiffusion; D007526:Isoelectric Point
chemical_list: D002352:Carrier Proteins; D004527:Egg Proteins; D001710:Biotin