Hunting for the “Sweet Spot”: Effects of Contiguous Guanines and Strand Lengths on the Catalytic Performance of DNA-Based Peroxidase Mimetics
Guanine-rich DNA strands have the potential to activate Cu2+ ions in peroxidase-like reactions based on the coordination of Cu2+ with nucleobases. Comparative studies on the number of guanines elucidate a sequence dependency that contiguous guanines are crucial to intrinsic peroxidase mimicking activities of DNA-Cu(II). The optimal number of repeat units to boost the enzyme-like activity of Cu2+ is identified via analyzing individual sequence of (T3G2)n and (T2G3)n. The catalytic performance of DNA-Cu(II) was found to be remarkably pH-tolerant through the H2O2-mediated oxidation of 3,3′,5,5′-tetramethylbenzidine at acidic pH, dopamine at neutral pH as well as methylene blue at alkaline pH, respectively. It is the first time to report that intrinsic peroxidase-like activities of DNA-Cu(II) are greatly associated with binding affinity and stoichiometry between Cu2+ and DNA. (T3G2)4-Cu(II) with a dominant 1:1 stoichiometry shows the K m toward H2O2 of 93 mM at pH 4.0 and 8.65 mM at pH 11.0. This study paves a way to rationally design artificial metalloenzymes, and the ability to tune the enzymatic activity would be harnessed for biocatalysis, biosensing, green synthesis and nanoscience.
Remarkable pH-tolerant peroxidase mimetics was constructed by direct coordination of Cu2+ within a guanine-rich DNA scaffold, of which the enzymatic activity is greatly associated with binding affinity and stoichiometry between Cu2+ and DNA. Intriguingly, there exist optimal guanine numbers and strand lengths to boost the catalytic performance of Cu2+.
KeywordsNucleic acid Copper ion Peroxidase Metalloenzyme Oxidation
This work was supported by the NSFC (21576206, 21621004), the Natural Science Foundation of Tianjin (15JCQNJC05800), and the Program for Changjiang Scholars and Innovative Research Team in University (IRT_15R46).