Fluorescence energy transfer between nucleotide binding sites in an F-action filament

Abstract

Fluorescence energy transfer between nucleotide binding sites in an F-actin filament was measured using 1- N 6-ethenoadenosine diphosphate (ε-ADP) as a fluorescent donor and 2′(or 3′)- O-(2,4,6-trinitrophenyl)adenosine 5′-diphosphate (TNP-ADP) as an acceptor, both of which were bound to F-actin. Taking into consideration the helical structure of the F-actin filament, the radial coordinate of the nucleotide binding site was calculated to be 25 Å, which corresponds to a distance between these sites along the long-pitch helix of 56.3 Å and along the genetic helix of 56.7 Å.