The general lack of empirical data for aqueous organic compounds at elevated temperature and pressure has lead to the development of various equations of state to describe the behavior of various thermodynamic properties at non-standard temperature and pressure. Only in a few works are there data available for compounds that are intermediates in the ubiquitous biochemical pathways found in nature. Most thermodynamic data available for aqueous organic molecules beyond the 25 ☌ and 0.1 MPa reference conditions are generally for compounds that are either potential growth substrates or metabolic by-products. Δ G f 0 a q) for each substance at non-standard temperature and pressure must be calculated.
#PROPERTY TABLE THERMODYNAMICS CALCULATOR FREE#
Δ G r 0) of reaction for a given set of products and reactants at temperatures and pressures beyond the 25 ☌ – 0.1 MPa reference conditions in an aqueous system, the standard Gibbs free energy of formation ( To evaluate the standard Gibbs free energy ( For examination of CAC reactions under the relatively extreme high-temperature and high-pressure conditions where life can thrive and may have originated, and to determine the geochemical environments where prebiotic conditions may have been favorable, the high pressure and temperature thermodynamic parameters of the substrates must be determined. Therefore it is difficult to predict accurate reaction thermodynamics well beyond those conditions, including those likely to have hosted the emergence of life. Most thermodynamic data available for the substrates used in the CAC are incomplete and have only been determined at the 25 ☌ and 0.1 MPa standard state.
Because of the fundamental metabolic roles and evolutionary importance of the CAC and the reverse CAC, it is of interest to understand the conditions constraining the many reactions of which it may be composed under the considerable range of physical and chemical environments where it functions. The key role of iron-sulfur proteins, thioester intermediates, and the reductive use of the CAC in hyperthermophilic autotrophs link the CAC to prebiotic theories of energy metabolism and abiotic carbon fixation at deep-sea hydrothermal vents. Organisms that use the CAC (or especially the reverse or reductive CAC) are represented among the most deeply-rooted autotrophic hyperthermophilic Archaea and Bacteria and the most derived of organotrophic evolutionary lineages. The citric acid cycle (CAC), also known as the Krebs or tricarboxylic acid cycle, is a fundamental pathway in intermediary metabolism among all the domains of life.
0 kommentar(er)
