An Anionic Surfactant Metallomicelle: Catalytic Activity and Mechanism for the Catalytic Hydrolysis of a Phosphate Ester

DNA Cleavage Activity: Comparison of two Lanthanum Complexes Based on Aza-Crown Ethers with Different Numbers of Nitrogen Atoms

Based on the unique characteristics of lanthanum ion and aza-crown ethers, the lanthanum complexes of two aza-crown ether (L1: 1,10-Dioxa-4,7,13,16-tetraazacyclo-octadecane and L2: 1,4,10,13-tetraoxa-7,16-diazacyclooctadecane) were designed and synthesised. The interaction between these two complexes and DNA was measured by UV-Vis spectroscopy and gel electrophoresis. Moreover, a series of experiments of cleavage of pUC19 DNA were conducted to illustrate the acidity, time and concentration effects. The results indicated that the two metal complexes can accelerate the breakage of DNA from its supercoiled form (form I) to the nicked form (form II) at near-physiological conditions, and the optimum acidity of DNA catalytic cleavage is pH=6.5 and pH=7.0 for LaL1 and LaL2, respectively. Furthermore, the LaL1 exhibited better cleavage activity than LaL2 under the same conditions, thus supercoiled DNA was thoroughly cleaved to the nicked form under the appropriate conditions. The hydrolytic mechanism was verified by applying several oxygen-scavengers to the DNA catalytic cleavage.

Development of the aza-crown ether metal complexes as artificial hydrolase

Hydrolases play a crucial role in the biochemical process, which can catalyze the hydrolysis of various compounds like carboxylic esters, phosphoesters, amides, nucleic acids, peptides, and so on. The design of artificial hydrolases has attracted extensive attention due to their scientific significance and potential applications in the field of gene medicine and molecular biology. Numerous macrocyclic metal complexes have been used as artificial hydrolase in the catalytic hydrolysis of the organic substrate. Aza-crown ether for this comment is a special class of the macrocyclic ligand containing both the nitrogen atoms and oxygen atoms in the ring. The studies showed that the aza-crown complexes exhibited high activity of hydrolytic enzyme. However, the aza-crown ether metal complex as artificial hydrolase is still very limited because of its difficulty in synthesis. This review summarizes the development of the aza-crown ether metal complexes as the artificial hydrolase, including the synthesis and catalysis of the transition metal complexes and lanthanide metal complexes of aza-crown ethers. The purpose of this review is to highlight: (1) the relationship between the structure and hydrolytic activity of synthetic hydrolase; (2) the synergistic effect of metal sites and ligands in the course of organic compound hydrolysis; and (3) the design strategies of the aza-crown ethers as hydrolase.