Journal
BIOPHYSICAL CHEMISTRY
Volume 105, Issue 2-3, Pages 585-593Publisher
ELSEVIER SCIENCE BV
DOI: 10.1016/S0301-4622(03)00068-1
Keywords
thermodynamic; kinetic analysis; biological signal transduction
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Based on a thermodynamic analysis of the kinetic model for the protein phosphorylation-dephosphorylation cycle, we study the ATP (or GTP) energy utilization of this ubiquitous biological signal transduction process. It is shown that the free energy from hydrolysis inside cells, DeltaG (phosphorylation potential), controls the amplification and sensitivity of the switch-like cellular module, the response coefficient of the sensitivity amplification approaches the optimal I and the Hill coefficient increases with increasing DeltaG. We discover that zero-order ultrasensitivity is mathematically equivalent to allosteric cooperativity. Furthermore, we show that the high amplification in ultrasensitivity is mechanistically related to the proofreading kinetics for protein biosynthesis. Both utilize multiple kinetic cycles in time to gain temporal cooperativity, in contrast to allosteric cooperativity that utilizes multiple subunits in a protein. (C) 2003 Elsevier Science B.V. All rights reserved.
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