The glycolytic clock is the prime example of a chemical Clock whose basis is regulated anaerobic sugar breakdown. This process is the simplest chemical energy converter in biology and occurs in all biological species known to date, including anaerobic bacteria and higher organisms, sometimes in modified or rudimentary form.
On the basis of experimental biochemical experience and theoretical studies, the possible functions of biochemical clocks can be generally summarized as follows - they work: 1. as a "clock" (»Taktgeber«) for the temporal organization of organisms. A biochemical clock can organize in time the myriad intracellular processes as well as the interactions between individual cells in multicellular associations. A classic example is the process of association of millions of slime mold cells in the case of Dictyostelium discoideum, which leads to the formation of a multicellular aggregate and is controlled by spatial oscillations of cyclic AMP. 2. for "dissipation saving" in the sense of reducing free energy losses compared to steady state. 3. as a "frequency generator" for other oscillatory systems, allowing a variety of new dynamic states to be generated. 4. as a "random generator" when chaos occurs, with the purpose of adapting the organism to new environmental conditions through trial and error. This function could be realized in chemotaxis and signal detection as well as in evolution. 5. as "information memory" in the sense of a chemical memory element, when different dynamic states occur for a fixed set of control parameters. In these cases, the behavior of the system is determined not only by the values of the control parameters, but also by the prior history of the system. Analogous processes could determine the memory character of individual oscillators in neural networks. Each oscillator could be singularly bound to a single cell. 6. as a "carrier oscillation" for endogenous low-frequency modulation. The observation of two different clock cycles in a simple dynamic process shows that the period of the carrier oscillation can be in the minute range and the modulating period in the hour range, which makes the old problem of the coupling of long-term and short-term rhythms understandable.
In these functions, excluding the chaotic functions, "hyperstability" would be a useful property if the vulnerability of the system to external disturbances is to be minimized. In the chaotic function, on the other hand, instability could be desirable as a macroscopic source of fluctuation to optimize the relations with the environment.
The variability of the system caused by the chaotic oscillations can be quantified by an information generation rate in bits/min. The information generation rate in the biochemical experiment of Fig. 9 b is 0.21 bits/min.
The manifold of modes of oscillation that a dynamical system can exhibit could be thought of as a "library" of waveforms. We have shown here the richness of waveforms of the "library" belonging to the glycolytic system. Switching from one waveform to another is achieved either by changing control parameters or by transitions in phase space between different coexisting trajectories. These transitions can be achieved by physical or biochemical pulses, in the manner of the metabolite pulses discussed here. The general structure of the glycolytic model system, composed of an allosteric and a so-called classical Michaelis enzyme, is found in many biochemical reaction trajectories of the cell. One may expect that the properties of the glycolytic clock presented here are also realized in other branches of biochemistry.
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HESS, Benno und Mario MARKUS, 1986. Chemische Uhren. In: Andreas DRESS, Hubert HENDRICHS und Günter KÜPPERS (Hrsg.), Selbstorganisation: die Entstehung von Ordnung in Natur und Gesellschaft. München: Piper. ISBN 978-3-492-03077-9
See Bynase