title: The X-ray three-dimensional structure of avidin.
abstract: Avidin is a basic, highly stable, homotetrameric protein, isolated from bird egg-white, binding up to four molecules of D-biotin with extremely high affinity (Kd approximately 10(-15) M). The protein has been the object of different crystallographic investigations. In all the crystal structures, the four avidin subunits display almost exact 222 symmetry. Each avidin chain (128 amino acids) is arranged in a eight-stranded antiparallel beta-barrel, whose inner region defines the D-biotin binding site. The molecular bases of D-biotin affinity can be recognised in a fairly rigid binding site, which is sterically complementary to the shape and polarity of the incoming vitamin, and is readily accessible in the apoprotein structure. Avidin displays remarkable structural and functional relationships to the acidic protein sretpavidin, isolated from Streptomyces avidinii.
authors.affiliation: Centro Biotecnologie Avanzate-IST and Dipartimento di Fisica-INFM, University of Genova, Italy.
authors.forename: C
authors.initials: C
authors.lastname: Rosano
authors.forename: P
authors.initials: P
authors.lastname: Arosio
authors.forename: M
authors.initials: M
authors.lastname: Bolognesi
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001360:Avidin / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D001665:Binding Sites; D001710:Biotin / Q000378:metabolism; D018360:Crystallography, X-Ray; D008958:Models, Molecular; D008969:Molecular Sequence Data; D015202:Protein Engineering; D020836:Protein Structure, Quaternary; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid; D019809:Streptavidin / Q000737:chemistry / Q000235:genetics / Q000378:metabolism
chemical_list: D001360:Avidin; D001710:Biotin; D019809:Streptavidin