Logic gates enzyme-based

Models for biochemical switches, logic gates, and information-processing devices that are also based on enzymic reactions but do not use the cyclic enzyme system were also introduced [76,115,117-122]. Examples of these models are presented in Table 1.3. It should also be mentioned that in other studies [108,112-114,116], models of chemical neurons and chemical neural networks based on nonenzymic chemical reactions were also introduced. 

S. Tuchman, S. Sideman, S. Kenig, and N. Lotan, Enzyme based logic gates controlled by outside signals principles and design, in Molecular Electronics and Molecular Electronic Devices, K. Sienicki, Ed., Vol. HI, CRC Press, Boca Raton, FL, 1994, pp. 223-238. 

Besides this approach based on oligonucleotides, there have been some notable efforts by Lotan and co-workers to use the enzymic activity of polypeptides as logic gates [91, 92]. These are particularly interesting because enzymatic activity can be viewed as an amplification process. 

Fig. 2 The signal-responsive membrane associated with an ITO electrode and coupled with the enzyme-based logic gates. (A) AFM topography images (10x10 pm ) of the membrane with the closed (a) and open (b) pores. (B) The electron transfer resistance, / et, of the switchable interface derived from the impedance spectroscopy measurements obtained upon different combinations of the input signals. The right and left bars correspond to the OR-Reset and AND-Reset systems, respectively. (Adapted from ref. 83, with permission Copyright American Chemical Society, 2009).

Zhou J, Arugula MA, Halmnek J, Pita M, Katz E. Enzyme-based NAND and NOR logic gates with modular design. J Phys Chem B 2009 113 16065-16070. 

Fig. 4.14 Plot of the results of a calculation of the steady-state concentration of frnctose 6-phosphate for the system shown in fig. 4.13. The enzyme models are either based on Michaelis-Menten formalisms or modifications of multiple allosteric effector equations. The gate exhibits a function with both AND and OR properties. At low concentrations of both inpnts, the mechanism functions similarly to an OR gate, while at simultaneously high concentrations of the inpnt species (citrate and cAMP), the output behavior more closely resembles a fuzzy logic AND gate. The mechanism satisfies the requirements for a fuzzy aggregation function. (From [7].)...

---