title: Role of a luciferin-binding protein in the circadian bioluminescent reaction of Gonyaulax polyedra.
abstract: A luciferin-binding protein (LBP), which binds and protects from autoxidation the substrate of the circadian bioluminescent reaction of Gonyaulax polyedra, has been purified to near homogeneity. The purified protein is a dimer with two identical 72-kDa subunits, and an isoelectric point of 6.7. LBP is a major component of the cells, comprising about 1% of the total protein during the night phase, but drops to only about 0.1% during the day. The luciferin is protected from autoxidation by binding to LBP, and one luciferin is bound per dimer at alkaline pH (Ka approximately 5 x 10(7) M-1). The protein undergoes a conformational change with release of luciferin at pH values below 7, concurrent with an activation of Gonyaulax luciferase. LBP thus has a dual role in the circadian bioluminescent system.
authors.affiliation: Department of Cellular and Developmental Biology, Harvard University, Cambridge, Massachusetts 02138.
authors.forename: D
authors.initials: D
authors.lastname: Morse
authors.forename: A M
authors.initials: AM
authors.lastname: Pappenheimer
authors.forename: J W
authors.initials: JW
authors.lastname: Hastings
mesh_terms: D000818:Animals; D002352:Carrier Proteins / Q000302:isolation & purification / Q000378:metabolism*; D002850:Chromatography, Gel; D002940:Circadian Rhythm; D004141:Dinoflagellida / Q000201:enzymology*; D004591:Electrophoresis, Polyacrylamide Gel; D049454:Firefly Luciferin / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008156:Luciferases / Q000378:metabolism; D008163:Luminescent Measurements
chemical_list: D002352:Carrier Proteins; D049454:Firefly Luciferin; D008156:Luciferases