title: Picosecond geminate recombination of CO to the complexes calmodulin*heme-CO and calmodulin*heme-CO*melittin.
abstract: Picosecond CO recombination kinetics have been measured after photodissociation of the artificial complexes calmodulin*heme-CO and calmodulin*heme-CO*melittin. These systems show an enhancement of the geminate fraction of kinetics relative to unbound heme-CO, due in part to fast geminate kinetics (tau=50ps for the initial phase), as well as a decrease in the rate of migration of CO away from the binding site. This indicates that calmodulin provides a complete pocket around the heme group. Rather than competing with the hemes for binding to calmodulin, the melittin seems to act as a cap to further enclose the hemes; melittin increases the affinity of calmodulin for heme-CO, but only weakly affects the CO recombination kinetics.
authors.affiliation: INSERM U299, Hôpital de Bicêtre, Le Kremlin Bicêtre, France.
authors.forename: E
authors.initials: E
authors.lastname: Leclerc-L'Hostis
authors.forename: S
authors.initials: S
authors.lastname: Franzen
authors.forename: J C
authors.initials: JC
authors.lastname: Lambry
authors.forename: J L
authors.initials: JL
authors.lastname: Martin
authors.forename: L
authors.initials: L
authors.lastname: Leclerc
authors.forename: C
authors.initials: C
authors.lastname: Poyart
authors.forename: M C
authors.initials: MC
authors.lastname: Marden
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D002118:Calcium / Q000737:chemistry / Q000494:pharmacology; D002147:Calmodulin / Q000737:chemistry* / Q000378:metabolism; D002248:Carbon Monoxide / Q000737:chemistry* / Q000378:metabolism; D006418:Heme / Q000737:chemistry* / Q000378:metabolism; D007700:Kinetics; D008555:Melitten / Q000737:chemistry* / Q000378:metabolism; D008969:Molecular Sequence Data; D010782:Photolysis; D013050:Spectrometry, Fluorescence; D013053:Spectrophotometry; D014783:Viscosity
chemical_list: D002147:Calmodulin; D008555:Melitten; D006418:Heme; D002248:Carbon Monoxide; D002118:Calcium