title: Spider hemocyanin binds ecdysone and 20-OH-ecdysone.
abstract: Fluorescence quenching studies and binding experiments with [(3)H]ecdysone reveal that the respiratory protein, hemocyanin, of the tarantula Eurypelma californicum binds ecdysone. The binding constant for ecdysone ranges between 0.5 and 5 mM, indicating a low affinity binding. However, it is comparable with those found for the ecdysone binding to hexamerins from insects. Based on a comparison of sequences and x-ray structures of arthropodan hemocyanins, we propose an evolutionary conserved hydrophobic pocket in domain 1 of the hemocyanin subunit that may bind ecdysone.
authors.affiliation: Institute for Molecular Biophysics, University of Mainz, D-55128 Mainz, Germany.
authors.forename: E
authors.initials: E
authors.lastname: Jaenicke
authors.forename: R
authors.initials: R
authors.lastname: Föll
authors.forename: H
authors.initials: H
authors.lastname: Decker
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D004440:Ecdysone / Q000378:metabolism*; D004441:Ecdysterone / Q000378:metabolism*; D006023:Glycoproteins / Q000235:genetics; D006433:Hemocyanins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D019476:Insect Proteins / Q000235:genetics; D007700:Kinetics; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013050:Spectrometry, Fluorescence; D013112:Spiders / Q000378:metabolism*; D014316:Tritium
chemical_list: D006023:Glycoproteins; D019476:Insect Proteins; C041137:storage proteins, Insecta; D014316:Tritium; D004440:Ecdysone; D004441:Ecdysterone; D006433:Hemocyanins