Volume 11 Supplement 10
Analysis of the functional properties of the creatine kinase system using a multiscale ‘sloppy’ modeling approach
© Hettling et al; licensee BioMed Central Ltd. 2010
Published: 07 December 2010
Distinct functions have been hypothesized for the creatine kinase (CK) enzyme catalyzing the reversible transfer of the high-energy phosphate group of ATP to creatine. In muscle cells, two CK isoforms might mediate (i) temporal energy buffering to maintain ATP homeostasis and (ii) energy transport from mitochondria to myofibrils via the “phosphocreatine shuttle” mechanism. Here we investigate the relative importance of the two roles using a computational model . Model simulations predict a contribution of CK to the net transcytosolic energy transport of less than 1/3.
Materials and methods
The model is validated on experimental data from two scales: kinetic parameter measurements on the enzyme level and response times of oxidative phosphorylation in whole cardiac muscle.
To account for possible inaccuracies in the 22 model parameters, we sample a Bayesian ensemble of parameter sets which allows us to set confidence regions on model predictions. In this ‘sloppy’ modeling approach , the likelihood of a parameter combination to be included in the ensemble is proportional to its likelihood to predict the data. We use prior information on single parameter values from enzyme kinetic measurements to constrain them within their measurement errors.
Our findings clearly support the hypothesis that CK acts as a high capacity temporal energy buffer damping energy peaks rather than being an essential energy transport system.
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