How Various Environmental Conditions Change the Catalytic Capacity of Biological Enzymes

Enzymes are biological catalysts which are responsible for the patterns of chemical transformations. The most striking characteristic of enzymes are their catalytic power and their specificity in the reaction. The specifity of an enzyme is due to the precise interaction of the substrate and the enzyme molecule and is used to the three-dimensional structure of the enzyme protein. Most enzymes and named for their substrates and for the reactions that they catalyze.

Enzymes can also be set to function by lowering the activation energy of the chemical reaction since enzymes accelerate reactions by decreasing ?G, which is the free energy of activation. The rate of the reaction is generally proportional to the concentration of the substrate, when all other things are kept constant.
The catalytic power of enzymes comes from the fact that they bring substrates together in a favorable orientation, which helps to promote the formation of the transition states in enzyme - substrate (ES) complexes.

Generally with internal catalyzed reactions, as substrate concentration increases, the rate of the reaction increases since more substrate molecules collide with enzyme molecules and hence more reactions take place.

At higher concentrations of substrate, the enzyme molecules become saturated so that there are only a few free enzyme molecules. Technically what type ends when the amount of enzyme is kept constant and the concentration of the substrate is increased, the reaction velocity will increase up to a maximum point. After this point any increase in substrate concentration will no longer increase the reaction velocity or rate.

Most enzymes generally have an optimum temperature at which they work best. For most mammalian enzymes, this temperature is around 40° C though most enzymes generally work at different temperatures depending on where they are found and their specific role. The rates of enzyme catalyzed reactions generally increases gradually up to their optimum temperature, the rate increase is due to the fact that the enzyme and some should molecules gain kinetic energy due to the increasing temperature so random collisions occur more often (random collisions are the cause of all chemical reactions).

Above the optimum temperature the rate of the reaction decreases due to the fact that the enzyme molecules become denatured. This denaturation disrupts the three-dimensional structure of the enzyme protein and causes it to loose function. The thermal energy from the increasing temperature causes the bonds holding the secondary and tertiary structures of the protein to be broken. The active site of the enzyme also loses its shape and that such substrates can no longer bind to the active site, and hence reaction velocity decreases.