1,N⁶-etheno-2-aza-adenosine triphosphate: Enormous increase in fluorescence intensity induced by its binding to heavy meromyosin and estimation of the kinetic parameters

The fluorescence spectrum of an ATP analogue, 1,N⁶-etheno-2-aza-adenosine triphosphate, changed greatly upon its binding to heavy meromyosin. The wavelength of the fluorescence maximum excited at 350 nm shifted from 485 nm to 453 nm and the fluorescence intensity at the maximum increased 2.8 times. The time course of the change in the fluorescence intensity measured at 440 nm with excitation at 350 nm was analyzed on the basis of a reaction scheme of Michaelis-Menten type. The analysis gave reasonable kinetic parameters for the hydrolysis of 1,N⁶-etheno-2-aza-adenosine triphosphate by heavy meromyosin.