Fluorescence studies of 1,N6-ethenoadenosine triphosphate bound to G-actin: the nucleotide base is inaccessible to water.
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.
Harvey
S C
SC
Biophysics Section, Department of Biomathematics, University of Alabama in Birmingham 35294, Birmingham, Alabama, USA.
Cheung
H C
HC
D000199:Actins / Q000737:chemistry* / Q000378:metabolism; D004985:Ethenoadenosine Triphosphate / Q000737:chemistry* / Q000378:metabolism; D013050:Spectrometry, Fluorescence; D014867:Water / Q000737:chemistry* / Q000378:metabolism
D000199:Actins; D004985:Ethenoadenosine Triphosphate; D014867:Water