title: Fluorescence energy transfer between points in G-actin: the nucleotide-binding site, the metal-binding site and Cys-373 residue.
abstract: Fluorescence energy transfers were studied in order to investigate the spatial relationships between the nucleotide-binding site, the metal-binding site and the Cys-373 residue in the G-actin molecule. When 1-N6-ethenoadenosine-5'-triphosphate (epsilon-ATP) in the nucleotide-binding site and Co2+ or Ni2+ in the metal-binding site were used as fluorescence donor and acceptor, respectively, the fluorescence intensity of epsilon-ATP was perfectly quenched by Ni2+ or Co2+. This indicated that the nucleotide-binding site is very close to the metal-binding site; the distance should be less than 10 A. When N-iodoacetyl-N'-(5-sulfo-1-naphthyl)ethylenediamine (IAEDANS) bound to Cys-373 residue and Co2+ in the metal-binding site were used as a fluorescence donor and an acceptor, respectively, the transfer efficiency was equal to 5 +/- 1%. The corresponding distance was calculated to be 23-32 A, assuming a random orientation factor K2 = 2/3.
mesh_terms: D000199:Actins / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000031:analogs & derivatives*; D000818:Animals; D001665:Binding Sites; D002118:Calcium / Q000378:metabolism; D002413:Cations, Divalent; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D003035:Cobalt / Q000378:metabolism*; D003545:Cysteine; D004735:Energy Transfer; D004985:Ethenoadenosine Triphosphate / Q000378:metabolism*; D005456:Fluorescent Dyes; D009282:Naphthalenesulfonates / Q000378:metabolism; D009532:Nickel / Q000378:metabolism*; D011817:Rabbits; D013050:Spectrometry, Fluorescence
chemical_list: D000199:Actins; D002413:Cations, Divalent; D004985:Ethenoadenosine Triphosphate; D005456:Fluorescent Dyes; D009282:Naphthalenesulfonates; D003035:Cobalt; C006421:1,5-I-AEDANS; D009532:Nickel; D000255:Adenosine Triphosphate; D003545:Cysteine; D002118:Calcium