Integrated and Organized Cellular Energetic Systems: Theories of Cell Energetics, Compartmentation, and Metabolic Channeling

Abstract

Bioenergetics as a part of biophysical chemistry and biophysics is a quantitative science that is based on several fundamental theories. The definition of energy itself is given by the first law of thermodynamics, and application of the second law of thermodynamics shows that living cells can function as open systems only where the internal order (low entropy state) is maintained due to increasing the entropy in the surrounding medium (Schrödinger's principle of negentropy). For this, the exchange of mass is needed, which gives rise to metabolism as the sum of catabolism and anabolism, and the free energy changes during catabolic reactions supply energy for all cellular work -osmotic, mechanical, and biochemical. The free energy changes during metabolic reactions obey the rules of chemical thermodynamics, which deals with Gibbs free energy of chemical reactions and with electrochemical potentials. For application of these theories to the integrated systems in vivo, complex cellular organization should be accounted for: macromolecular crowding; metabolic channeling and functional coupling mechanisms due to close and tight protein-protein interactions; compartmentation of the enzymes due to their attachment to the subcellular membranes or connection to the cytoskeleton; and both macro-and microcompartmentation of substrates and metabolites in the cells. Because of this, almost all processes important for cell life are localized within small areas of the cell, and for their integration effective systems of communication, including compartmentalized energy transfer systems, are required. These are represented in muscle cells by the phosphotransfer networks, mostly by the creatine kinase and adenylate kinase systems, whose alterations under ischemic conditions contribute significantly to acute ischemic contractile failure of the heart. 59 Molecular System Bioenergetics: Energy for Life. Edited by Valdur Saks

The Mechanism of Erythrocytes Aggregation in EDTA-Blood of Ovarian Cancer Patients Viewed by Coulomb’s Law

“…They can exchange their entropy if they are far from equilibrium condition. The system is in steady state if the input and output are in equilibrium condition and do not show growth, but this does not match living organisms [30] [32].…”

“…The direction of all processes that occur spontaneously is explained by the second law of Thermodynamics. The irreversible process moves towards increasing entropy [32]. The combination of these two laws in constant temperature (T) and pressure (p) condition describes the relationship of thermodynamic system state function changes, called Gibbs (∆G), enthalpy (∆H), and entropy (∆S) free energies is showed by the equation (2) [32] [33].…”

The phosphocreatine–creatine kinase system helps to shape muscle cells and keep them healthy and alive

“…The role of this system in muscle, brain and other tissue with high energy requirements and fluxes has been intensively studied and debated during the last four decades. The main results and current state of art of these studies were recently summarized in a number of chapters of three almost simultaneously published books (Vial, 2006;Wallimann et al 2007;Dzeja et al 2007;Saks et al 2007;Wyss & Salomon, 2007). These studies helped to develop the new paradigm of bioenergetic studiesmolecular system bioenergetics, a part of systems biology (Saks et al 2006.…”

“…These studies helped to develop the new paradigm of bioenergetic studiesmolecular system bioenergetics, a part of systems biology (Saks et al 2006. The important role of the PCr-CK system is based on the metabolic compartmentation of adenine nucleotides and modular organization of energy metabolism -both are system level properties not predictable from properties of isolated components of the cell (Weiss et al 2006;Saks et al 2007). Abundant experimental evidence shows the existence of distinct cellular ATP microdomains (compartments) localized in mitochondria and at the sites of ATP utilization.…”

“…Abundant experimental evidence shows the existence of distinct cellular ATP microdomains (compartments) localized in mitochondria and at the sites of ATP utilization. These are connected by phosphotransfer networks, notably via the PCr-creatine kinase pathway (reviewed by Wallimann et al 2007;Dzeja et al 2007;Saks et al 2007;Wyss & Salomon, 2007). These networks function to bypass and overcome local restrictions on ATP or ADP diffusion and thus perform the important tasks of both energy supply and metabolic feedback regulation of respiration (Saks et al 2006).…”