مرکز منطقه ای اطلاع رساني علوم و فناوري -

چكيده لاتين :

A highly sensitive spectroscopic method using dichlorofluorescin (LDCF) was employed to study the rate of electron-transfer reaction in presence of dsDNA, ssDNA and some metal ions and imidazole derivative (N-trans cinnamoyl imidazole).Our results show that both kinds of DNA possess an enzyme-like catalytic activity in oxidative conversion of non fluorescent LDCF to fluorescent DCF. A biphasic saturation curve was observed when the reaction velocities were measured at fixed concentration of dsDNA, ssDNA and variable amounts of cinnamoyl imidazole. Each of biphasic phase gave the values of Km1=1* 10 ^-6 M, and Vm1=20.8 (delta)F/min with Km2=1* 10^-4 M, Vm2=8.7 (delta)F/min for dsDNA and Km1=2*10^-6 M, Vm1=16.62 (delta)F/min and Km2=4*10^-4 M, Vm2=29.2 (delta)F/min for ssDNA. Among investigated metal ions Mn and Cd caused inhibition of ET reaction in presence of DNA and imidazole while Cu and Ca activated the reaction. A linear correlation was found between conductivity of each metal ion and activation or inhibition of reaction in presence of dsDNA and ssDNA. A model was devised based on the catalytic properties of DNA in reaction with cinnamoyl imidazole and metal ions in which the release of electron produced by reaction could be facilitated by the presence of the cinnamoyl imidazole which could transfer the electron through its conjugated structure to the DNA chord via metal ion. The more conductive metal, the higher was the catalysis.