Issue 2, 2015

Enhancement of deoxyribozyme activity by cationic copolymers

Abstract

Deoxyribozymes, or DNAzymes, are DNA molecules with enzymatic activity. DNAzymes with ribonuclease activity have various potential applications in biomedical and bioanalytical fields; however, most constructs have limited turnover despite optimization of reaction conditions and DNAzyme structures. A cationic comb-type copolymer accelerates DNA hybridization and strand exchange rates, and we hypothesized that the copolymer would enhance deoxyribozyme activity by promoting turnover. The copolymer did not change DNAzyme activity under single-turnover conditions, suggesting that the copolymer affects neither the folding structure of DNAzyme nor the association of a divalent cation, a catalytic cofactor, to DNAzyme. The copolymer enhanced activity of the evaluated DNAzyme over a wide temperature range under multiple-turnover conditions. The copolymer increased the DNAzyme kcat/KM by fifty-fold at 50 °C, the optimal temperature for the DNAzyme in the absence of the copolymer. The acceleration effect was most significant when the reaction temperature was slightly higher than the melting temperature of the enzyme/substrate complex; acceleration of two orders of magnitude was observed. We concluded that the copolymer accelerated the turnover step without influencing the chemical cleavage step. In contrast to the copolymer, a cationic surfactant, CTAB, strongly inhibited the DNAzyme activity under either single- or multiple-turnover conditions.

Graphical abstract: Enhancement of deoxyribozyme activity by cationic copolymers

Supplementary files

Article information

Article type
Paper
Submitted
23 Jul 2014
Accepted
11 Sep 2014
First published
03 Oct 2014
This article is Open Access
Creative Commons BY license

Biomater. Sci., 2015,3, 308-316

Author version available

Enhancement of deoxyribozyme activity by cationic copolymers

J. Gao, N. Shimada and A. Maruyama, Biomater. Sci., 2015, 3, 308 DOI: 10.1039/C4BM00256C

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