Energy Managements in the Chemical and Biochemical World, as It may be Understood from the Systems Chemistry Point of View

Abstract

If anyone compares biochemical and industrial processes from energetic point of view, it may well be concluded that the bio-production of any living entity exhibits far greater energy efficiency than any human controlled industrial production. Most of the bioreactions take place at the same cell at the same temperature, within a narrow range, without external heating or cooling system. In contrast to that, industrial chemical processes usually proceed separately at various reaction temperatures from –80 °C to +200 °C. Furthermore, these reactions require significantly larger energy input, which is taken in either as external heating or internal molecular energy of active reagents (high energy reagents, like acylhalogenides and LiBH4), meanwhile the large excess of energy waste, released during the reaction, must be led away. Behind the high efficacy of biological processes compared to man-made processes there are two energetic reasons. At first, biological reactions used to start from low energy intermediates and proceed by means of very well designed catalysts, such as enzymes, therefore activation energy gaps are low (Figure 1, green line), consequently reaction can be carried out at ambient temperature. Secondly, reagents used by living organism, like NAD+, FAD, ATP and other bio-reagents are so effectives under enzymatic conditions, that they need to store only slightly more than the necessary energy within their structures to carry out the reaction, resulting low energy waste, or in other word, reagents balance the reaction energy by their internal molecular energy. Two non-catalyzed laboratory processes (black dashed and red lines) are compared with a enzyme catalyzed biological process (green line) schematically in Figure 1 and Table 1. For any reaction to proceed, sufficient reagent has to be chosen, which at Gibbs free energy level is higher than the Gibbs free energy level of the product. The Gibbs free energy difference between the row material and product (GI → GF) is called built-in energy. To prepare active reagent from row material, some energy needs to be invested (GI → G1 and GI → G3). Under laboratory conditions I (black, dashed line), instead of the addition of high energy and very active reagents, we react only low energy reagent (at G1), therefore thermal energy via increased reaction temperature need to be input (G1 → G5), consequently the waste energy is high. In laboratory condition II (red line), normally high energy and active reagent is reacted via low transition state (G3 → G4), it does not require high reaction temperature. However, the overall waste energy remained