Enzyme Action The molecular events that accompany the conversion of substrate into products constitute the mechanism of enzyme action. Enzyme action on its substrate results either in the formation or degradation of chemical bonds in the substrate molecules. 1. ES Complex Formation According to Michaelis – Menton theory, the enzyme E combines with the substrate S to form an intermediate enzyme substrate complex ES. This complex then breaks down into product P and enzyme E is regenerated. The enzyme can again combine with the fresh molecule of the substrate in similar manner. The formation of enzyme substrate complex as an intermediate during the reaction has been proved by spectroscopic studies. So, a simple enzymatic reaction might be written as Where E, S and P represent enzyme, substrate and product respectively. ES and EP are complexes of the enzyme with substrate and product respectively. At the end of the reaction along with the required pr...
Oxidative phosphorylation Hydrogens or their electrons, pass down the electron transport chain in a series of redox reaction. The electrons entering the electron transport system have relatively high energy content. As they pass along the chain of electron acceptors, they lose much of their energy, some of which is used to pump the protons across the inner mitochondrial membrane. The flow of electrons in the electron transport is usually coupled tightly to the production of ATP with the help of the enzyme ATP synthetase, and it does not occur unless the phosphorylation of ADP can also proceed. This prevents a waste of energy, because high-energy electrons do not flow unless ATP can be produced. Because the phosphorylation of ADP to form ATP is coupled with the oxidation of electron transport components, this process of making ATP is referred to as oxidative phosphorylation. The electron transport and oxidative phosphorylation depends upon the availability of ADP and Pi and...
High energy compounds The high energy compound is the ATP. The other high energy compoundsinclude ADP,1,3-diphospho glycerate, phosphoenol pyruvate and also creatine phosphate. The phosphate group of the high energy phosphate may transfer directly to another organic compound. For this reason the term group transfer potential is preferred by some high energy bond. However, the phosphorylated compound may or may not have high energy phosphate bond, though the total energy content of the molecule is higher than a non phosphorylated compound. Storage form of high energy compounds They are called as phosphogens and help to store the high energy. The example for this the creatine phosphate present in the vertebrate muscles, the reaction works in both directions it is a reversible reaction form ATP when ATP is required. When ATP is more, creatine reacts with ATP and forms the phosphocreatine. 1. 1, 3-diphosphoglycerate One of the phosphate ...
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