Relationship between biotin-binding proteins from chicken plasma and egg yolk

• Published in: Biochemical journal 1978-11, Vol.175 (2), p.629-633
• Main Authors: Mandella, R D, Meslar, H W, White, 3rd, H B
• Format: Article
• Language: English
• Subjects: Animals; Biotin - blood; Biotin - metabolism; Carrier Proteins - blood; Carrier Proteins - metabolism; Chickens; Chromatography, Gel; Chromatography, Ion Exchange; Egg Proteins - metabolism; Egg Yolk - analysis; Female; Immunodiffusion; Isoelectric Point
• ISSN: 0264-6021; 1470-8728
• DOI: 10.1042/bj1750629

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.