Control analysis of transition times in metabolic systems. |
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Authors: | E Meléndez-Hevia N V Torres J Sicilia and H Kacser |
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Institution: | Departamento de Bioquímica y Biología Molecular, Facultad de Biología, Universidad de La Laguna, Tenerife, Canary Islands, Spain. |
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Abstract: | The transition time, tau, of a metabolic system is defined as the ratio of the metabolite concentrations in the system, sigma, to the steady-state flux, J. Its value reflects a temporal characteristic of the system as it relaxes towards the steady state. Like other systemic properties, the value of tau will be a function of the enzyme activities in the system. The influence of a particular enzyme activity on tau can be quantified by a Control Coefficient, C tau ei. We show that it is possible to derive a Summation Theorem sigma ni = 1 C tau ei = -1 and a Connectivity Theorem sigma ni = 1 C tau ei.epsilon viSk = -Sk/sigma. We establish a 'sign rule' that predicts the order of positive and negative Control Coefficients in a sequence. |
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