The Lactate Dehydrogenase

The lactate dehydrogenase

Enzymes:

Enzymes are protein molecules which catalyst the biological reactions within living systems [23]. They provide a reaction surface to which a substrate can easily bind and a suitable environment for the reaction to occur. They bring the reactants together and orient them in such a way that they attain their transition-state configurations. They weaken the high-energy bonds in the reactants, so that the reaction can occur fast and give a product which is then released [8]. Sometimes, the enzymes may also participate in the mechanism of reaction but remain unchanged at the end of the reaction [6, 18].

An enzyme catalyzed reaction is a reversible reaction which means that the reaction can occur in both the directions. Thus an enzyme can be defined as an agent that speeds up the approach to equilibrium with the starting materials and products being unaffected [8].

One of the most important and basic function of an enzyme is to increase the speed of the reaction they catalyze [6, 18]. This is done by lowering the activation energy, which is the energy difference between the starting material and the transition state, and it is the size of this activation energy that determines the rate of a reaction [8].

"Most cellular reactions occur about a million times faster than they would in the absence of an enzyme" [6].

Enzymes function with high specificity for only one reactant and catalyze the specific reactions compared to most chemical catalysts which catalyze a wide range of reactions. The enzyme contains an active site which is the area with an appropriate shape and functional groups to allow the reactant or substrate to bind to the enzyme. The binding can preferably be inhibited by the enzyme with the help of inhibitor. An enzyme also contains a non-protein part called cofactors [8]. The cofactor may be a either

* An organic group called prosthetic group which binds permanently to enzyme [8]

* Positively charged metal ions...