Spe ctral stud ies on the binding of cationic Zn(II)tet rapyridin oporphyr azine to ca lf thymus DNA an d oligonuc leotide

Cationic tetraazaporphirins, or porphirazin es, represent an alter native and highly under developed class of cationic porphyrinic com pounds. Microcycles h asted on the porphyrazi ne core, inc luding phethalocyanins , but the replacement of the mes o methylene carbons of porphyrins with nitrogen in porphyrazines creates profound differences [۲]. For example, pophyraz ines absorb more strongly at longer wavelengths a critical feature in b iological an d medical applications [۱].The present work was undertak en to determ ine the equilibrium bin ding proces ses of N, N ´, N´´, N´´´ tetramethy ltetra-۳,۴-pyridinoporphyrazinato zinc(II) [Zn(tmtppa)] to calf thym us DNA (ct DNA) and characterize d binding target by using of synth etic nucleotide G-C, A- T. In this way binding constants, binding modes, the values of the Stern̽Volmer constant (KS V) and the rate constants for the que nching (kq) were deter mined by using optical absorption an d fluoresce nce spectroscopy.