Temperature-controlled encapsulation and release of an active enzyme in the cavity of a self-assembled DNA nanocage.

We demonstrate temperature-controlled encapsulation and release of the enzyme horseradish peroxidase using a preassembled and covalently closed three-dimensional DNA cage structure as a controllable encapsulation device. The utilized cage structure was covalently closed and composed of 12 double-stranded B-DNA helices that constituted the edges of the structure. The double stranded helices were interrupted by short single-stranded thymidine linkers constituting the cage corners except for one, which was composed by four 32 nucleotide long stretches of DNA with a sequence that allowed them to fold into hairpin structures.

Structural dynamics of nucleic acids by single-molecule FRET.

Single-molecule Förster Resonance Energy Transfer (smFRET) has emerged as a powerful technique to study biological processes at the molecular level. It provides detailed information on the structural dynamics of nucleic acids and proteins on the nanometer scale under a wide variety of conditions. Studying each molecule individually allows going beyond traditional ensemble averaging experiments.