title: Fluorescence studies of 1,N6-ethenoadenosine triphosphate bound to G-actin: the nucleotide base is inaccessible to water.
abstract: When 1,N6-ethenoadenosine triphosphate (epsilon-ATP) is free in solution, its fluorescence is collisionally quenched by iodide ion, by methionine, by tryptophan, and by cysteine. None of these quenches the fluorescence of epsilon-ATP bound to G-actin. Thus, the ethenoadenine base is bound in a region of the protein which is inaccessible to collisions with these reagents. Since we have previously shown that the fluorescence of epsilon-ATP is quenched by water, the long lifetime of epsilon-ATP bound to G-actin (36 nsec, vs 27 nsec for epsilon-ATP in water) indicates that the bound nucleotide base is inaccessible to collisional quenching by water molecules.
authors.affiliation: Biophysics Section, Department of Biomathematics, University of Alabama in Birmingham 35294, Birmingham, Alabama, USA.
authors.forename: S C
authors.initials: SC
authors.lastname: Harvey
authors.forename: H C
authors.initials: HC
authors.lastname: Cheung
mesh_terms: D000199:Actins / Q000737:chemistry* / Q000378:metabolism; D004985:Ethenoadenosine Triphosphate / Q000737:chemistry* / Q000378:metabolism; D013050:Spectrometry, Fluorescence; D014867:Water / Q000737:chemistry* / Q000378:metabolism
chemical_list: D000199:Actins; D004985:Ethenoadenosine Triphosphate; D014867:Water