Autocatalytic and oscillatory reaction networks that form guanidines and products of their cyclization

Autocatalytic and oscillatory networks of organic reactions are important for designing life-inspired materials and for better understanding the emergence of life on Earth; however, the diversity of the chemistries of these reactions is limited. In this work, we present the thiol-assisted formation of guanidines, which has a mechanism analogous to that of native chemical ligation. Using this reaction, we designed autocatalytic and oscillatory reaction networks that form substituted guanidines from thiouronium salts. The thiouronium salt-based oscillator show good stability of oscillations within a broad range of experimental conditions. By using nitrile-containing starting materials, we constructed an oscillator where the concentration of a bicyclic derivative of dihydropyrimidine oscillates. Moreover, the mixed thioester and thiouronium salt-based oscillator show unique responsiveness to chemical cues. The reactions developed in this work expand our toolbox for designing out-of-equilibrium chemical systems and link autocatalytic and oscillatory chemistry to the synthesis of guanidinium derivatives and the products of their transformations including analogs of nucleobases.

ATP oscillation caused by Gradual Entry of Substrates within Mitochondria

The gradual entry of the substrate into enzyme solution causes the oscillatory reaction. We proved this by using dialysis membrane as a means of gradual entry of substrates 7. It was considered that a suitable combination of permeation rate through membrane of the substrate and rate constants for catalytic reaction regulates the oscillation. It was suggested that such oscillatory reactions also should occur in actual living organisms. On the basis of this suggestion, we explored the oscillatory reaction within mitochondria, because many reactions in mitochondria also occur in the mediation of membrane. We found that the gradual entry of pyruvate together with ADP caused the oscillations of both NADH and ATP within mitochondria. Likewise, the gradual entry of NAD+ and malate together with ADP caused the oscillations of NADH and of ATP. At the same time, pH oscillation within mitochondria was also observed. Besides the experiment with mitochondria, we also investigated oscillations of NADH and the other intermediates using dialysis membrane both in the citric acid cycle and in the respiratory chain. Putting these together, we concluded that the oscillatory reactions caused by the gradual entry of pyruvate occur continuously both in the citric acid cycle and in the respiratory chain and is taken over finally by the reaction of ATP synthase in the oxidative phosphorylation, inducing the oscillation of ATP. Furthermore, it was found that oscillations occurred without going through the citric acid cycle when NAD+ and malate were used instead of pyruvate.

APPLICABILITY OF BRAY-LIEBHAFSKY REACTION FOR CHEMICAL COMPUTING

The first discovered homogeneous oscillatory reaction was the Bray-Liebhafsky (BL) one, described in a paper published exactly 100 years ago. However, the applicability of oscillatory reactions in chemical computing was recently discovered. Here we intend to expose the native computing concept applied to intermittent states of the BL reaction, because we believe that this particular state may have some advantages. For this purpose, numerical simulations will be used based on the known model. Sequences of perturbations will be introduced by adding iodate (IO3-) and hydrogen peroxide (H2O2), separately, as well as in various combinations with one another. It will be shown that dynamic states obtained after perturbations with same species depend very much on the sequence in which these species were used in perturbations. Additionally, it will be shown that obtained dynamic states shift the system from chaotic intermittent dynamic state to different complex periodic states. Hence, the applicability of the BL reaction system in chemical computing was demonstrated.

A possible connection between phosphate tungsten bronzes properties and Briggs-Rauscher oscillatory reaction response

The calcium phosphate tungsten bronze (Ca-PWB) has been synthesized and characterized (TGA, DSC, XRPD, FTIR, SEM). The influence of solid insoluble materials Ca- PWB, as well as lithium doped (Li-PWB) and cation free phosphate tungsten (PWB) bronzes on the oscillatory Briggs-Rauscher (BR) reaction dynamics, is compared. The results show that doping with Li and Ca reduces sensitivity of the BR reaction towards bronzes addition. These findings suggest the usage of the BR reaction as an innovative method for testing of different properties of bronze material. The behavior of PWB in the BR reaction is significantly changed with divalent cation (Ca2+) doping. The reasons for the different bronzes behavior were found in their calculated unit cell volumes. Namely, the compressed Ca-PWB unit cell volume indicates the difficult availability of the active site for heterogeneous catalysis. Hence, the linear correlation (slope) of the BR oscillogram?s length (?osc) vs. mass of bronze in BR reaction might be considered as a new parameter for the evaluation of the bronzes catalytic activity.

Long-time dynamics of a stochastic multimolecule oscillatory reaction model with Poisson jumps

<abstract><p>This paper reveals dynamical behaviors in the stochastic multimolecule oscillatory reaction model with Poisson jumps. First, this system is proved to have a unique global positive solution via the Lyapunov technique. Second, the existence and uniqueness of general random attractors for its stochastic homeomorphism flow is proved by the comparison theorem, and meanwhile, a criterion for the existence of singleton sets is obtained. Finally, numerical simulations are used to illustrate the predicted random attractors.</p></abstract>