Mechanism for enzymatic reaction
As for the mechanism, there are different theorist comes out by expert to explain on how the enzyme action:
(i)Lock and key theory:
According to Fildes only a particular substrate could be mix with the active site of a certain enzyme as a specialized key fits to open a specific lock. In this enzyme molecule produce an active site to fit in with the substrate forming Energy Substrate complex. When reaction completed energy substrate complex breaks into products and enzymes. Enzymes remain unbroken.
(ii)Inducted fit Theory:
According to Koshland, when a one fit substrate comes to bind with the active site of an enzyme, the substrate take into the process, some conformational form of enzyme changes in due to the attractive groups and supporting groups form a complementary structure so that the catalytic group of the active site is in position of the bonds to be broken.
Most of chemical reactions, energy limit that exists has got to get control of the reaction to happen. This barrier are made to avoid complex molecules such as nucleic acids and proteins from automatically decrease, which is important for life maintenance. Metabolic changes are required in a cell, even so some of these complex molecules must be broken down, and this energy limit should be overcome. Heat could provide the additional energy but if too much temperature increase, the cell could be kill. Another ways is adding some catalyst to lower the activation energy level. So, in order for a reaction to occur, reactant molecules must contain enough energy to pass through a potential energy barrier which called as the “activation energy”. All molecules occupy inconstant amounts of energy depending on their recent collision that just happen but, usually, only a few of the molecule have sufficient energy for reaction. The lower the potential energy barrier to reaction, then the reactants have sufficient energy and, hence the faster reaction will occur.
This is where the enzyme play the important role. They react with the substrate to form an intermediate complex or called as transition state that requires minimum energy for the reaction to proceed. The unsteady intermediate compound then breaks down to produce reaction products, and the stable enzyme is free to react with other substrate molecules. For the uncatalysed reaction, it can be found within all catalysts together with enzymes which function by forming a transition state with the reactants of a lower free energy. Even most of the reaction in this potential energy barrier could produce high values in the rate of reaction. On the enzyme, not all part of it are the active site but only certain of it do have which then will bind to substrate. The active site have a spot or hole formed by the bend pattern of the protein. The 3D structure with the chemical and electrical characteristic of a co-factors within the active site, allows only a specific substrate to bind to the site which then determining the enzyme’s specificity.
The end product of reaction depends on the successful completion of each reaction from 5 stage depend on the substrate, each resolve by a specific enzyme. The enzymes in a series can be located closed by each other so it can lower the time taken for reaction process. Beside that intermediate products will continue the process without makes a mess in the pathway, making the process more efficient. By removing intermediates or deduct end products from the reactive pathway, the equilibrium effects are minimized. Since equilibrium is not achieved the reactions will proceed to the right direction.