Preparation And DNA Cleaving Activity Of Amino Acid-Polyamine Conjugate Derivatives

For decades, chemical nuclein cleaving agents, the artificial nuclease undergo a rapid development in the field of chemical biology. Different from the metallo-nuclease, which is a biomimetic system related to type II restriction endonuclease, cleaving nuclein without transition metal ion, metal-free artificial nucleases have attracted significant interest by their low toxic and stable properties.Continuing the former studies in our research group, in this communication, degradable and environmental friendly poly-aspartic acid was employed as DNA cleaving agent. To study the assistant effect of DNA binding agent, replaced the binding agents, rigid benzimidazole was induced instead of fordable macrocyclic polyamine. Meanwhile, in order to study the structure activity relationship of poly aspartic acid, we designed several conjugate derivatives of cyclen-tripeptide of aspartic acid. Protected by different protecting group, either carboxyl groups in poly-aspartic acid or amino groups in cyclen was disabled, so that we discuss the function regulating the DNA hydrolysis of the moieties in cleaving molecule.In this article, the polymer compound, poly-aspartic acid benzimidazole (PASP-IDB) conjugate derivative was synthesized, chemical properties and structure charactered by 1H-NMR,13C-NMR and MALDI-TOF. Through the assay of agarose gel electrophoresis, under circumstance of non-metal ion, PASP-IDB regulated DNA double strand hydrolysis by non-random path. Then we discuss the cleaving mode, which is the necessity of carboxyl moiety, via modification of the ungrafted carboxyl by propyl and hydroxyethyl. With the help of fluorescence spectrum, we further studied and proposed the cleaving mechanism of PASP-IDB.In order to further understand the cleaving model of the polymer PASP-cyclen studied in latest period, we designed and synthesized tripeptides-cyclen derivatives, such as Asp(cyclen)-Asp(All)-Asp(All)-All, Asp(cyclen)-Asp(All)-Asp(All)-OH, Asp(cyclen)-Asp-Asp(All)-OH, Asp(cyclen)-Asp-Asp-OH and Boc-Asp(3Boc-cyclen)-Asp-Asp-OH. In agarose gel electrophoresis, we derived the apparent rate constant Kobs. Both carboxyl moiety in aspartic acid residue and amino acid group in cyclen joint together in cleaving process, contributing the molecule regulation of the nuclein hydrolyzed. When number of carboxyl moieties increased, we find out that hydrolysis activity of the cleaving molecule increased gradually.