Spectrofluorimetric Study on the Weak Interaction between ATP and N_α-4-Tosyl-L-arginine Methyl Ester Hydrochloride

In this paper, some new results on the selective weak interaction between N_α-4-tosyl-L-arginine methyl ester hydrochloride (TAME) and adenosine-5′-triphosphate (ATP) have been reported. Fluorescence spectrophotometry and Fourier transform infrared (FT-IR) spectroscopy were used to investigate this kind of weak interaction. In fluorescence experiments, obvious fluorescence quenching phenomena were observed when TAME was added, which indicated the weak interactions between TAME and ATP. It has been identified by fluorescence titration experiments that TAME exhibited high selectivity to ATP over ADP and AMP. FT-IR spectral results showed that an ATP-TAME adduct was formed. The experimental results indicated that the interaction sites were the guanidinium group of TAME main-chain and the γ-phosphate group of ATP, and the interaction took place through hydrogen bonding and electrostatic force. In addition, the effects of metal ions on the weak interaction between ATP and TAME, or between ATP and analogues of L-arginine were studied.