title: Identification and molecular characterisation of a biotin-binding protein distinct from avidin of chicken egg white and comparison with yolk biotin-binding protein.
abstract: By immunological and biochemical methods a biotin-binding protein, distinct from avidin, has been shown to be present in chicken egg white. This vitamin-binding protein (Mr 67,000) bound [14C]biotin, displayed thermally induced biotin exchange reaction and exhibited gross immunological cross-reactivity with the purified yolk biotin-binding protein. In vitro labelling of soluble proteins with radioactive amino acids in the oviduct tissue explants from estrogenised chicks revealed that approx. 2% of the total radioactive proteins was immunoprecipitated with anti-yolk biotin-binding protein antibodies. The protein could be purified to homogeneity by employing ion-exchange chromatography on DEAE-cellulose and biotin-AH Sepharose affinity chromatography. The purified protein specifically bound [14C]biotin, and exhibited complete immunological homology with the yolk biotin-binding protein but not with avidin. Its electrophoretic mobility (at pH 8.3), acidic nature, biotin-binding characteristics, immunological cross-reactivity and tryptic peptide maps were very similar to that of yolk biotin-binding protein, and not avidin.
mesh_terms: D000818:Animals; D001360:Avidin / Q000378:metabolism*; D002352:Carrier Proteins / Q000032:analysis*; D002645:Chickens; D003429:Cross Reactions; D004529:Egg White; D004530:Egg Yolk; D005260:Female; D005779:Immunodiffusion; D008970:Molecular Weight; D010449:Peptide Mapping
chemical_list: D002352:Carrier Proteins; C017071:biotin-binding proteins; D001360:Avidin