Liu and Lu employed a single-strand linker DNA that contained the aptamer sequence to induce the aggregation of AuNPs; the addition of adenosine dissembled the aggregated AuNPs and resulted in a purple-to-red color change .
When the adenosine is present, the aptamer-target binding displaced the Watson-Crick binding between the Apt and the linker DNA sequence on QDs, which induces the conformational switch of the Apt from loose random coil to a G-quadruplex structure, which disassembles the original duplex and the QDs were separated from the AuNPs, affording fluorescence "turn-on" state due to the far distance between donor and acceptor (Scheme 1c).
The other product is "oligo(dG)-tailed linker DNA," which has an oligo(dG) tail at one end and a HindIII cohesive end at the other end.
Step 4 is annealing and circularization with oligo(dG)-tailed linker DNA and E.
(31) Basically, the plasmid for the preparation of the vector primer is required only to contain a fragment composed of one HindIII site, a unique restriction site and a 3'-protruding rare restriction site in this order, whereas the plasmid for the preparation of the linker DNA is required to contain a fragment composed of a 3'-protruding unique restriction site and one HindIII site.
Another histone, H1, is located outside the nucleosomes at the so-called linker DNA
, which connects the various 206-kDa disk-like nucleosomes.
Each nucleosome is joined to adjacent nucleosomes by regions of linker DNA
. The linker regions of DNA range from 20 to 40 by and flank each side of a nucleosome outside the region of interaction between H1 and nucleosomal DNA.