Design, Fabrication, and Applications of DNA Nanomachines - DNA Nanotechnology: From Structure to Function - page 229

Fig. 11.6 ( a ) Coherent activation of two tweezers by AMP and adenosine deaminase ( AD ),
acting as a SET-RESET logic device (Reprinted with permission from Ref. [ 49 ]. Copyright 2009
American Chemical Society). ( b ) Cocurrent activation of three tweezers using one equivalent of
the linker that can close any of the tweezers, instructed by the added fuels (Hg 2C , cysteine, H C ,or
OH ). The operation results in the automata with four possible states. ( c ) Scheme of all 16 states
of the automaton, established by a three-tweezers system with six kinds of fuels (Hg 2C , cysteine,
H C ,OH , or complementary linker strands) (( b )and( c ) are reprinted with permission from Ref.
[ 50 ]. Copyright 2010 National Academy of Sciences, U.S.A.)
strand and be closed, in the absence of AMP in the solution, while the other tweezer
(tweezer B) arm is empty and in open configuration (state I, (0,1)) (Fig. 11.6 a)
[ 48 ]. Once with the addition of AMP, the free strands on tweezer A arms showed
stronger affinity to AMP than the target strand, which was then released to tweezer
B, resulting in the opening of tweezer A and the closure of tweezer B (state II, (1,0)).
Thereafter, by the treatment of adenosine deaminase, AMP was transformed to ino-
sine monophosphate (IMP), incapable of being recognized by the aptamer sequence,
and the target strand returned and closed tweezer A, and tweezer B opened. Thermal
inactivation of the enzyme and re-addition of AMP released the target strand from
tweezers again. Repeated addition of AMP and adenosine deaminase activated
tweezers A and B concurrently. There were several energetic premise in designing
the free strands of arms of tweezers A and B: (1) the target strand hybridized to
the free strands of tweezer A stronger than tweezer B in the absence of AMP; (2)
the aptamer sequence on the arms of tweezer A preferred to bind the substrate AMP
than the target strand; and (3) the target strand formed the stable duplex with the free