Gamma-amido-ATP stabilizes a high-fluorescence state of myosin subfragment 1.
On binding to myosin subfragment 1 (S1), the gamma-amido derivative of ATP (ATPgammaNH2), an isomer of adenosine 5'-[beta,gamma-imido]-triphosphate (AMPPNP), induces a larger increase in the intrinsic (tryptophan) fluorescence than is seen with ATP. A binding constant of 1.7x10(7) M(-1) was measured for ATPgammaNH2, compared to 2.1-2.4x10(7) M(-1) for AMPPNP. ATPgammaNH2 was hydrolyzed only very slowly by S1. ATPgammaNH2 appears to stabilize the 'closed' conformation of S1, and does so without cleavage of the beta-gamma phosphate bond. The dissociation of actin-S1 by ATPgammaNH2 and that of S1.ATPgammaNH2 by actin are both strikingly slow.
Wray
John
J
Abteilung Biophysik, Max-Planck-Institut für Medizinische Forschung, Jahnstr. 29, 69120, Heidelberg, Germany. wray@mpimf-heidelberg.mpg.de
Jahn
Werner
W
D000205:Actomyosin / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000031:analogs & derivatives* / Q000378:metabolism / Q000494:pharmacology*; D000266:Adenylyl Imidodiphosphate / Q000031:analogs & derivatives / Q000378:metabolism; D000818:Animals; D005453:Fluorescence; D006868:Hydrolysis; D007700:Kinetics; D015879:Myosin Subfragments / Q000737:chemistry* / Q000378:metabolism; D011817:Rabbits; D013696:Temperature; D014364:Tryptophan / Q000737:chemistry
D015879:Myosin Subfragments; C523355:gamma-amido-adenosine triphosphate; D000266:Adenylyl Imidodiphosphate; D014364:Tryptophan; D000255:Adenosine Triphosphate; D000205:Actomyosin