The synthesis of a fluorinated ATP analog, 2-fluoro-ATP (2-flATP), is described. This analog is designed for 19F nuclear magnetic resonance (NMR) studies of large enzymes and proteins which bind adenine nucleotides. 2-flATP is shown to be active as an ATP analog in a number of enzyme systems, and its 19F-NMR properties are determined. Specifically the principal elements of the 19F-NMR chemical shift tensor are shown to be 104, 12, and -116 ppm. The complex between 2-flADP and the myosin subfragment-1 ATPase is studied by 19F NMR, comparing the normal Michaelis complex and 2-flADP "trapped" on subfragment-1. These complexes are shown to be indistinguishable from the standpoint of the environment and mobility of the adenine ring.