By means of digital simulation, the saturation of threshold-type responses has been observed with a model system composed of several emzymatic reactions (Okuyama et al.. 1977). The model included rate constants which depended upon the product concentration : In the present study, this dependency was eliminated in order to simplify the model, but the saturation was attained again. It was found that a feed-forward circuit, which was still set in the simplifed model, played an important role in establishing the saturated state. In order to sexrch the molecular mechanism of the feed-forward loop, it was assumed that the loop was composed of a subsystem equilibrating between active and inactive forms of an enzyme. Contrary to expectation, the saturation of threshold-type response was achieved only when the equilibrium of the above enzymatic system favored greatly thr inactive form.
Mendeley出力
