title: Subdomain IIIA of dog albumin contains a binding site similar to site II of human albumin.
abstract: Dog albumin contains a specific drug-binding site that binds most of the site II ligands of human albumin. This study was undertaken to elucidate the structural configuration of this binding site using a photoaffinity labeling technique. Dog albumin and albumins of other animal species were photolabeled with [(14)C]ketoprofen. The photolabeled albumins were cleaved with cyanogen bromide (CNBr) and analyzed autoradiographically after electrophoretic separation. A 11.6-kDa CNBr fragment of the photolabeled dog albumin was found to have incorporated most of the radioactivity. Site II ligands of human albumin inhibited photoincorporation of radioactivity to this fragment. The binding constants of human and dog albumins ranged from 10 to 12 x 10(5) M(-1), at least twice as high as those of rat, rabbit, and bovine albumins. Edman degradation was performed to elucidate the amino acid sequence of the photolabeled peptide derived from further digestion of the dog 11.6-kDa CNBr fragment with lysyl endopeptidase. The sequence was XXSESLVXRX, which corresponds to Cys(476)-Arg(485) of dog albumin. Dog albumin contains a binding site that may have a binding microenvironment similar to that of site II on human albumin. Therefore, dog may be a better experimental animal for data extrapolation from animal to human with regard to site II drug-drug interactions.
authors.affiliation: Graduate School of Pharmaceutical Sciences, Kumamoto University, Kumamoto, Japan.
authors.forename: Ken-ichi
authors.initials: K
authors.lastname: Kaneko
authors.forename: Hikaru
authors.initials: H
authors.lastname: Fukuda
authors.forename: Victor Tuan Giam
authors.initials: VT
authors.lastname: Chuang
authors.forename: Keishi
authors.initials: K
authors.lastname: Yamasaki
authors.forename: Kohichi
authors.initials: K
authors.lastname: Kawahara
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Nakayama
authors.forename: Ayaka
authors.initials: A
authors.lastname: Suenaga
authors.forename: Toru
authors.initials: T
authors.lastname: Maruyama
authors.forename: Masaki
authors.initials: M
authors.lastname: Otagiri
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001345:Autoradiography; D001665:Binding Sites; D002250:Carbon Radioisotopes; D002417:Cattle; D002851:Chromatography, High Pressure Liquid; D004285:Dogs; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D008024:Ligands; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry / Q000378:metabolism*; D004364:Pharmaceutical Preparations / Q000097:blood / Q000737:chemistry; D019920:Photoaffinity Labels; D011485:Protein Binding; D011817:Rabbits; D051381:Rats; D012709:Serum Albumin / Q000737:chemistry / Q000378:metabolism*; D013045:Species Specificity
chemical_list: D002250:Carbon Radioisotopes; D008024:Ligands; D010446:Peptide Fragments; D004364:Pharmaceutical Preparations; D019920:Photoaffinity Labels; D012709:Serum Albumin