Synthesis and Properties of N6-(2, 4-Dinitrophenyl)-adenosine 5′-Triphosphate, an Analog of ATP

Abstract

An analog of ATP, N⁶-(2,4-dinitrophenyl)-adenosine 5′-triphosphate (DNP-ATP), in which a dinitrophenyl group replaces a hydrogen of the 6-amino group of the ade-nine base, has been synthesized by the reaction of FDNB with ATP under mild conditions. The DNP-ATP prepared was homogeneous on paper chromatography and could replace ATP for heavy meromyosin ATPase [EC 3.6.1.3]. Heavy mero-myosin catalyzed the release of the terminal phosphate from DNP-ATP at V_max, 0.33 μmole per min per mg, which was 57% of that observed for ATP. The difference spectrum of heavy meromyosin induced by DNP-ATP was measured in the presence of MgCl2. The spectrum showed two peaks at 281 μ and at 288 μ, a shoulder at 292 μ, and broad negative troughs in the 240 to 270 μ region and in the 300 to 360 μ region. The hypochromicity at the higher μ wavelength is due to the interaction of the dinitrophenyl group with heavy meromyosin. The difference absorbance at 320 μ observed after the addition of DNP-ATP was a function of the concentration of DNP-ATP added. However, the plot deviated from a hyperbolic curve, having a sigmoidal character.